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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Bengtsson%2C+A&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Bengtsson%2C+A&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Bengtsson%2C+A&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.14360">arXiv:2412.14360</a> <span> [<a href="https://arxiv.org/pdf/2412.14360">pdf</a>, <a href="https://arxiv.org/format/2412.14360">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Demonstrating dynamic surface codes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Eickbusch%2C+A">Alec Eickbusch</a>, <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Sivak%2C+V">Volodymyr Sivak</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Claes%2C+J">Jahan Claes</a>, <a href="/search/quant-ph?searchtype=author&query=Kafri%2C+D">Dvir Kafri</a>, <a href="/search/quant-ph?searchtype=author&query=Gidney%2C+C">Craig Gidney</a>, <a href="/search/quant-ph?searchtype=author&query=Warren%2C+C+W">Christopher W. Warren</a>, <a href="/search/quant-ph?searchtype=author&query=Gross%2C+J">Jonathan Gross</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+N+Z+K+C">Nicholas Zobrist Kevin C. Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Roberts%2C+G">Gabrielle Roberts</a>, <a href="/search/quant-ph?searchtype=author&query=Satzinger%2C+K+J">Kevin J. Satzinger</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Neeley%2C+M">Matthew Neeley</a>, <a href="/search/quant-ph?searchtype=author&query=Livingston%2C+W+P">William P. Livingston</a>, <a href="/search/quant-ph?searchtype=author&query=Greene%2C+A">Alex Greene</a>, <a href="/search/quant-ph?searchtype=author&query=Rajeev"> Rajeev</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya"> Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a>, <a href="/search/quant-ph?searchtype=author&query=Aigeldinger%2C+G">Georg Aigeldinger</a>, <a href="/search/quant-ph?searchtype=author&query=Alcaraz%2C+R">Ross Alcaraz</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a> , et al. (193 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.14360v1-abstract-short" style="display: inline;"> A remarkable characteristic of quantum computing is the potential for reliable computation despite faulty qubits. This can be achieved through quantum error correction, which is typically implemented by repeatedly applying static syndrome checks, permitting correction of logical information. Recently, the development of time-dynamic approaches to error correction has uncovered new codes and new co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.14360v1-abstract-full').style.display = 'inline'; document.getElementById('2412.14360v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.14360v1-abstract-full" style="display: none;"> A remarkable characteristic of quantum computing is the potential for reliable computation despite faulty qubits. This can be achieved through quantum error correction, which is typically implemented by repeatedly applying static syndrome checks, permitting correction of logical information. Recently, the development of time-dynamic approaches to error correction has uncovered new codes and new code implementations. In this work, we experimentally demonstrate three time-dynamic implementations of the surface code, each offering a unique solution to hardware design challenges and introducing flexibility in surface code realization. First, we embed the surface code on a hexagonal lattice, reducing the necessary couplings per qubit from four to three. Second, we walk a surface code, swapping the role of data and measure qubits each round, achieving error correction with built-in removal of accumulated non-computational errors. Finally, we realize the surface code using iSWAP gates instead of the traditional CNOT, extending the set of viable gates for error correction without additional overhead. We measure the error suppression factor when scaling from distance-3 to distance-5 codes of $螞_{35,\text{hex}} = 2.15(2)$, $螞_{35,\text{walk}} = 1.69(6)$, and $螞_{35,\text{iSWAP}} = 1.56(2)$, achieving state-of-the-art error suppression for each. With detailed error budgeting, we explore their performance trade-offs and implications for hardware design. This work demonstrates that dynamic circuit approaches satisfy the demands for fault-tolerance and opens new alternative avenues for scalable hardware design. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.14360v1-abstract-full').style.display = 'none'; document.getElementById('2412.14360v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 5 figures, Supplementary Information</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.14256">arXiv:2412.14256</a> <span> [<a href="https://arxiv.org/pdf/2412.14256">pdf</a>, <a href="https://arxiv.org/format/2412.14256">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Scaling and logic in the color code on a superconducting quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lacroix%2C+N">Nathan Lacroix</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Heras%2C+F+J+H">Francisco J. H. Heras</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L+M">Lei M. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Bausch%2C+J">Johannes Bausch</a>, <a href="/search/quant-ph?searchtype=author&query=Senior%2C+A+W">Andrew W. Senior</a>, <a href="/search/quant-ph?searchtype=author&query=Edlich%2C+T">Thomas Edlich</a>, <a href="/search/quant-ph?searchtype=author&query=Shutty%2C+N">Noah Shutty</a>, <a href="/search/quant-ph?searchtype=author&query=Sivak%2C+V">Volodymyr Sivak</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Higgott%2C+O">Oscar Higgott</a>, <a href="/search/quant-ph?searchtype=author&query=Kafri%2C+D">Dvir Kafri</a>, <a href="/search/quant-ph?searchtype=author&query=Claes%2C+J">Jahan Claes</a>, <a href="/search/quant-ph?searchtype=author&query=Morvan%2C+A">Alexis Morvan</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zalcman%2C+A">Adam Zalcman</a>, <a href="/search/quant-ph?searchtype=author&query=Madhuk%2C+S">Sid Madhuk</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a>, <a href="/search/quant-ph?searchtype=author&query=Aigeldinger%2C+G">Georg Aigeldinger</a>, <a href="/search/quant-ph?searchtype=author&query=Alcaraz%2C+R">Ross Alcaraz</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a> , et al. (190 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.14256v1-abstract-short" style="display: inline;"> Quantum error correction is essential for bridging the gap between the error rates of physical devices and the extremely low logical error rates required for quantum algorithms. Recent error-correction demonstrations on superconducting processors have focused primarily on the surface code, which offers a high error threshold but poses limitations for logical operations. In contrast, the color code… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.14256v1-abstract-full').style.display = 'inline'; document.getElementById('2412.14256v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.14256v1-abstract-full" style="display: none;"> Quantum error correction is essential for bridging the gap between the error rates of physical devices and the extremely low logical error rates required for quantum algorithms. Recent error-correction demonstrations on superconducting processors have focused primarily on the surface code, which offers a high error threshold but poses limitations for logical operations. In contrast, the color code enables much more efficient logic, although it requires more complex stabilizer measurements and decoding techniques. Measuring these stabilizers in planar architectures such as superconducting qubits is challenging, and so far, realizations of color codes have not addressed performance scaling with code size on any platform. Here, we present a comprehensive demonstration of the color code on a superconducting processor, achieving logical error suppression and performing logical operations. Scaling the code distance from three to five suppresses logical errors by a factor of $螞_{3/5}$ = 1.56(4). Simulations indicate this performance is below the threshold of the color code, and furthermore that the color code may be more efficient than the surface code with modest device improvements. Using logical randomized benchmarking, we find that transversal Clifford gates add an error of only 0.0027(3), which is substantially less than the error of an idling error correction cycle. We inject magic states, a key resource for universal computation, achieving fidelities exceeding 99% with post-selection (retaining about 75% of the data). Finally, we successfully teleport logical states between distance-three color codes using lattice surgery, with teleported state fidelities between 86.5(1)% and 90.7(1)%. This work establishes the color code as a compelling research direction to realize fault-tolerant quantum computation on superconducting processors in the near future. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.14256v1-abstract-full').style.display = 'none'; document.getElementById('2412.14256v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.06557">arXiv:2410.06557</a> <span> [<a href="https://arxiv.org/pdf/2410.06557">pdf</a>, <a href="https://arxiv.org/format/2410.06557">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> </div> <p class="title is-5 mathjax"> Observation of disorder-free localization and efficient disorder averaging on a quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gyawali%2C+G">Gaurav Gyawali</a>, <a href="/search/quant-ph?searchtype=author&query=Cochran%2C+T">Tyler Cochran</a>, <a href="/search/quant-ph?searchtype=author&query=Lensky%2C+Y">Yuri Lensky</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Karamlou%2C+A+H">Amir H. Karamlou</a>, <a href="/search/quant-ph?searchtype=author&query=Kechedzhi%2C+K">Kostyantyn Kechedzhi</a>, <a href="/search/quant-ph?searchtype=author&query=Berndtsson%2C+J">Julia Berndtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Westerhout%2C+T">Tom Westerhout</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Astrakhantsev%2C+N">Nikita Astrakhantsev</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Ballard%2C+B">Brian Ballard</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a> , et al. (195 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.06557v1-abstract-short" style="display: inline;"> One of the most challenging problems in the computational study of localization in quantum manybody systems is to capture the effects of rare events, which requires sampling over exponentially many disorder realizations. We implement an efficient procedure on a quantum processor, leveraging quantum parallelism, to efficiently sample over all disorder realizations. We observe localization without d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06557v1-abstract-full').style.display = 'inline'; document.getElementById('2410.06557v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.06557v1-abstract-full" style="display: none;"> One of the most challenging problems in the computational study of localization in quantum manybody systems is to capture the effects of rare events, which requires sampling over exponentially many disorder realizations. We implement an efficient procedure on a quantum processor, leveraging quantum parallelism, to efficiently sample over all disorder realizations. We observe localization without disorder in quantum many-body dynamics in one and two dimensions: perturbations do not diffuse even though both the generator of evolution and the initial states are fully translationally invariant. The disorder strength as well as its density can be readily tuned using the initial state. Furthermore, we demonstrate the versatility of our platform by measuring Renyi entropies. Our method could also be extended to higher moments of the physical observables and disorder learning. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06557v1-abstract-full').style.display = 'none'; document.getElementById('2410.06557v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.17142">arXiv:2409.17142</a> <span> [<a href="https://arxiv.org/pdf/2409.17142">pdf</a>, <a href="https://arxiv.org/format/2409.17142">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> </div> <p class="title is-5 mathjax"> Visualizing Dynamics of Charges and Strings in (2+1)D Lattice Gauge Theories </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cochran%2C+T+A">Tyler A. Cochran</a>, <a href="/search/quant-ph?searchtype=author&query=Jobst%2C+B">Bernhard Jobst</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Lensky%2C+Y+D">Yuri D. Lensky</a>, <a href="/search/quant-ph?searchtype=author&query=Gyawali%2C+G">Gaurav Gyawali</a>, <a href="/search/quant-ph?searchtype=author&query=Eassa%2C+N">Norhan Eassa</a>, <a href="/search/quant-ph?searchtype=author&query=Will%2C+M">Melissa Will</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Ballard%2C+B">Brian Ballard</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Browne%2C+D+A">David A. Browne</a> , et al. (167 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.17142v1-abstract-short" style="display: inline;"> Lattice gauge theories (LGTs) can be employed to understand a wide range of phenomena, from elementary particle scattering in high-energy physics to effective descriptions of many-body interactions in materials. Studying dynamical properties of emergent phases can be challenging as it requires solving many-body problems that are generally beyond perturbative limits. We investigate the dynamics of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.17142v1-abstract-full').style.display = 'inline'; document.getElementById('2409.17142v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.17142v1-abstract-full" style="display: none;"> Lattice gauge theories (LGTs) can be employed to understand a wide range of phenomena, from elementary particle scattering in high-energy physics to effective descriptions of many-body interactions in materials. Studying dynamical properties of emergent phases can be challenging as it requires solving many-body problems that are generally beyond perturbative limits. We investigate the dynamics of local excitations in a $\mathbb{Z}_2$ LGT using a two-dimensional lattice of superconducting qubits. We first construct a simple variational circuit which prepares low-energy states that have a large overlap with the ground state; then we create particles with local gates and simulate their quantum dynamics via a discretized time evolution. As the effective magnetic field is increased, our measurements show signatures of transitioning from deconfined to confined dynamics. For confined excitations, the magnetic field induces a tension in the string connecting them. Our method allows us to experimentally image string dynamics in a (2+1)D LGT from which we uncover two distinct regimes inside the confining phase: for weak confinement the string fluctuates strongly in the transverse direction, while for strong confinement transverse fluctuations are effectively frozen. In addition, we demonstrate a resonance condition at which dynamical string breaking is facilitated. Our LGT implementation on a quantum processor presents a novel set of techniques for investigating emergent particle and string dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.17142v1-abstract-full').style.display = 'none'; document.getElementById('2409.17142v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.13687">arXiv:2408.13687</a> <span> [<a href="https://arxiv.org/pdf/2408.13687">pdf</a>, <a href="https://arxiv.org/format/2408.13687">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum error correction below the surface code threshold </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Aghababaie-Beni%2C+L">Laleh Aghababaie-Beni</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">Igor Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Astrakhantsev%2C+N">Nikita Astrakhantsev</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Ballard%2C+B">Brian Ballard</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bausch%2C+J">Johannes Bausch</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Blackwell%2C+S">Sam Blackwell</a>, <a href="/search/quant-ph?searchtype=author&query=Boixo%2C+S">Sergio Boixo</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Browne%2C+D+A">David A. Browne</a> , et al. (224 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.13687v1-abstract-short" style="display: inline;"> Quantum error correction provides a path to reach practical quantum computing by combining multiple physical qubits into a logical qubit, where the logical error rate is suppressed exponentially as more qubits are added. However, this exponential suppression only occurs if the physical error rate is below a critical threshold. In this work, we present two surface code memories operating below this… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13687v1-abstract-full').style.display = 'inline'; document.getElementById('2408.13687v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.13687v1-abstract-full" style="display: none;"> Quantum error correction provides a path to reach practical quantum computing by combining multiple physical qubits into a logical qubit, where the logical error rate is suppressed exponentially as more qubits are added. However, this exponential suppression only occurs if the physical error rate is below a critical threshold. In this work, we present two surface code memories operating below this threshold: a distance-7 code and a distance-5 code integrated with a real-time decoder. The logical error rate of our larger quantum memory is suppressed by a factor of $螞$ = 2.14 $\pm$ 0.02 when increasing the code distance by two, culminating in a 101-qubit distance-7 code with 0.143% $\pm$ 0.003% error per cycle of error correction. This logical memory is also beyond break-even, exceeding its best physical qubit's lifetime by a factor of 2.4 $\pm$ 0.3. We maintain below-threshold performance when decoding in real time, achieving an average decoder latency of 63 $渭$s at distance-5 up to a million cycles, with a cycle time of 1.1 $渭$s. To probe the limits of our error-correction performance, we run repetition codes up to distance-29 and find that logical performance is limited by rare correlated error events occurring approximately once every hour, or 3 $\times$ 10$^9$ cycles. Our results present device performance that, if scaled, could realize the operational requirements of large scale fault-tolerant quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13687v1-abstract-full').style.display = 'none'; document.getElementById('2408.13687v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 4 figures, Supplementary Information</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.04891">arXiv:2406.04891</a> <span> [<a href="https://arxiv.org/pdf/2406.04891">pdf</a>, <a href="https://arxiv.org/format/2406.04891">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> Dispersive Qubit Readout with Intrinsic Resonator Reset </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jerger%2C+M">M. Jerger</a>, <a href="/search/quant-ph?searchtype=author&query=Motzoi%2C+F">F. Motzoi</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y">Y. Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Dickel%2C+C">C. Dickel</a>, <a href="/search/quant-ph?searchtype=author&query=Buchmann%2C+L">L. Buchmann</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">G. Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Warren%2C+C+W">C. W. Warren</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">J. Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=DiVincenzo%2C+D">D. DiVincenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/quant-ph?searchtype=author&query=Bushev%2C+P+A">P. A. Bushev</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.04891v2-abstract-short" style="display: inline;"> A key challenge in quantum computing is speeding up measurement and initialization. Here, we experimentally demonstrate a dispersive measurement method for superconducting qubits that simultaneously measures the qubit and returns the readout resonator to its initial state. The approach is based on universal analytical pulses and requires knowledge of the qubit and resonator parameters, but needs n… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.04891v2-abstract-full').style.display = 'inline'; document.getElementById('2406.04891v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.04891v2-abstract-full" style="display: none;"> A key challenge in quantum computing is speeding up measurement and initialization. Here, we experimentally demonstrate a dispersive measurement method for superconducting qubits that simultaneously measures the qubit and returns the readout resonator to its initial state. The approach is based on universal analytical pulses and requires knowledge of the qubit and resonator parameters, but needs no direct optimization of the pulse shape, even when accounting for the nonlinearity of the system. Moreover, the method generalizes to measuring an arbitrary number of modes and states. For the qubit readout, we can drive the resonator to $\sim 10^2$ photons and back to $\sim 10^{-3}$ photons in less than $3 魏^{-1}$, while still achieving a $T_1$-limited assignment error below 1\%. We also present universal pulse shapes and experimental results for qutrit readout. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.04891v2-abstract-full').style.display = 'none'; document.getElementById('2406.04891v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.17385">arXiv:2405.17385</a> <span> [<a href="https://arxiv.org/pdf/2405.17385">pdf</a>, <a href="https://arxiv.org/format/2405.17385">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Thermalization and Criticality on an Analog-Digital Quantum Simulator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Astrakhantsev%2C+N">Nikita Astrakhantsev</a>, <a href="/search/quant-ph?searchtype=author&query=Karamlou%2C+A+H">Amir H. Karamlou</a>, <a href="/search/quant-ph?searchtype=author&query=Berndtsson%2C+J">Julia Berndtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Motruk%2C+J">Johannes Motruk</a>, <a href="/search/quant-ph?searchtype=author&query=Szasz%2C+A">Aaron Szasz</a>, <a href="/search/quant-ph?searchtype=author&query=Gross%2C+J+A">Jonathan A. Gross</a>, <a href="/search/quant-ph?searchtype=author&query=Schuckert%2C+A">Alexander Schuckert</a>, <a href="/search/quant-ph?searchtype=author&query=Westerhout%2C+T">Tom Westerhout</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yaxing Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Forati%2C+E">Ebrahim Forati</a>, <a href="/search/quant-ph?searchtype=author&query=Rossi%2C+D">Dario Rossi</a>, <a href="/search/quant-ph?searchtype=author&query=Kobrin%2C+B">Bryce Kobrin</a>, <a href="/search/quant-ph?searchtype=author&query=Di+Paolo%2C+A">Agustin Di Paolo</a>, <a href="/search/quant-ph?searchtype=author&query=Klots%2C+A+R">Andrey R. Klots</a>, <a href="/search/quant-ph?searchtype=author&query=Drozdov%2C+I">Ilya Drozdov</a>, <a href="/search/quant-ph?searchtype=author&query=Kurilovich%2C+V+D">Vladislav D. Kurilovich</a>, <a href="/search/quant-ph?searchtype=author&query=Petukhov%2C+A">Andre Petukhov</a>, <a href="/search/quant-ph?searchtype=author&query=Ioffe%2C+L+B">Lev B. Ioffe</a>, <a href="/search/quant-ph?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/quant-ph?searchtype=author&query=Rath%2C+A">Aniket Rath</a>, <a href="/search/quant-ph?searchtype=author&query=Vitale%2C+V">Vittorio Vitale</a>, <a href="/search/quant-ph?searchtype=author&query=Vermersch%2C+B">Benoit Vermersch</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a> , et al. (202 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.17385v2-abstract-short" style="display: inline;"> Understanding how interacting particles approach thermal equilibrium is a major challenge of quantum simulators. Unlocking the full potential of such systems toward this goal requires flexible initial state preparation, precise time evolution, and extensive probes for final state characterization. We present a quantum simulator comprising 69 superconducting qubits which supports both universal qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.17385v2-abstract-full').style.display = 'inline'; document.getElementById('2405.17385v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.17385v2-abstract-full" style="display: none;"> Understanding how interacting particles approach thermal equilibrium is a major challenge of quantum simulators. Unlocking the full potential of such systems toward this goal requires flexible initial state preparation, precise time evolution, and extensive probes for final state characterization. We present a quantum simulator comprising 69 superconducting qubits which supports both universal quantum gates and high-fidelity analog evolution, with performance beyond the reach of classical simulation in cross-entropy benchmarking experiments. Emulating a two-dimensional (2D) XY quantum magnet, we leverage a wide range of measurement techniques to study quantum states after ramps from an antiferromagnetic initial state. We observe signatures of the classical Kosterlitz-Thouless phase transition, as well as strong deviations from Kibble-Zurek scaling predictions attributed to the interplay between quantum and classical coarsening of the correlated domains. This interpretation is corroborated by injecting variable energy density into the initial state, which enables studying the effects of the eigenstate thermalization hypothesis (ETH) in targeted parts of the eigenspectrum. Finally, we digitally prepare the system in pairwise-entangled dimer states and image the transport of energy and vorticity during thermalization. These results establish the efficacy of superconducting analog-digital quantum processors for preparing states across many-body spectra and unveiling their thermalization dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.17385v2-abstract-full').style.display = 'none'; document.getElementById('2405.17385v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.15644">arXiv:2402.15644</a> <span> [<a href="https://arxiv.org/pdf/2402.15644">pdf</a>, <a href="https://arxiv.org/format/2402.15644">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Resisting high-energy impact events through gap engineering in superconducting qubit arrays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+K+C">Kevin C. Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">Alex Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Crook%2C+A">Alex Crook</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Kreikebaum%2C+J+M">John Mark Kreikebaum</a>, <a href="/search/quant-ph?searchtype=author&query=Zobrist%2C+N">Nicholas Zobrist</a>, <a href="/search/quant-ph?searchtype=author&query=Jeffrey%2C+E">Evan Jeffrey</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+B">Bicheng Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+H">Hung-Shen Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Dunsworth%2C+A">Andrew Dunsworth</a>, <a href="/search/quant-ph?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yaxing Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Forati%2C+E">Ebrahim Forati</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Iveland%2C+J">Justin Iveland</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wayne Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+S">Seon Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Megrant%2C+A">Anthony Megrant</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/quant-ph?searchtype=author&query=Sank%2C+D">Daniel Sank</a> , et al. (2 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.15644v2-abstract-short" style="display: inline;"> Quantum error correction (QEC) provides a practical path to fault-tolerant quantum computing through scaling to large qubit numbers, assuming that physical errors are sufficiently uncorrelated in time and space. In superconducting qubit arrays, high-energy impact events produce correlated errors, violating this key assumption. Following such an event, phonons with energy above the superconducting… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.15644v2-abstract-full').style.display = 'inline'; document.getElementById('2402.15644v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.15644v2-abstract-full" style="display: none;"> Quantum error correction (QEC) provides a practical path to fault-tolerant quantum computing through scaling to large qubit numbers, assuming that physical errors are sufficiently uncorrelated in time and space. In superconducting qubit arrays, high-energy impact events produce correlated errors, violating this key assumption. Following such an event, phonons with energy above the superconducting gap propagate throughout the device substrate, which in turn generate a temporary surge in quasiparticle (QP) density throughout the array. When these QPs tunnel across the qubits' Josephson junctions, they induce correlated errors. Engineering different superconducting gaps across the qubit's Josephson junctions provides a method to resist this form of QP tunneling. By fabricating all-aluminum transmon qubits with both strong and weak gap engineering on the same substrate, we observe starkly different responses during high-energy impact events. Strongly gap engineered qubits do not show any degradation in T1 during impact events, while weakly gap engineered qubits show events of correlated degradation in T1. We also show that strongly gap engineered qubits are robust to QP poisoning from increasing optical illumination intensity, whereas weakly gap engineered qubits display rapid degradation in coherence. Based on these results, gap engineering removes the threat of high-energy impacts to QEC in superconducting qubit arrays. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.15644v2-abstract-full').style.display = 'none'; document.getElementById('2402.15644v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.00413">arXiv:2402.00413</a> <span> [<a href="https://arxiv.org/pdf/2402.00413">pdf</a>, <a href="https://arxiv.org/format/2402.00413">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> System Characterization of Dispersive Readout in Superconducting Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Khezri%2C+M">Mostafa Khezri</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Naaman%2C+O">Ofer Naaman</a>, <a href="/search/quant-ph?searchtype=author&query=Korotkov%2C+A">Alexander Korotkov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.00413v1-abstract-short" style="display: inline;"> Designing quantum systems with the measurement speed and accuracy needed for quantum error correction using superconducting qubits requires iterative design and test informed by accurate models and characterization tools. We introduce a single protocol, with few prerequisite calibrations, which measures the dispersive shift, resonator linewidth, and drive power used in the dispersive readout of su… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00413v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00413v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00413v1-abstract-full" style="display: none;"> Designing quantum systems with the measurement speed and accuracy needed for quantum error correction using superconducting qubits requires iterative design and test informed by accurate models and characterization tools. We introduce a single protocol, with few prerequisite calibrations, which measures the dispersive shift, resonator linewidth, and drive power used in the dispersive readout of superconducting qubits. We find that the resonator linewidth is poorly controlled with a factor of 2 between the maximum and minimum measured values, and is likely to require focused attention in future quantum error correction experiments. We also introduce a protocol for measuring the readout system efficiency using the same power levels as are used in typical qubit readout, and without the need to measure the qubit coherence. We routinely run these protocols on chips with tens of qubits, driven by automation software with little human interaction. Using the extracted system parameters, we find that a model based on those parameters predicts the readout signal to noise ratio to within 10% over a device with 54 qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00413v1-abstract-full').style.display = 'none'; document.getElementById('2402.00413v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.02321">arXiv:2308.02321</a> <span> [<a href="https://arxiv.org/pdf/2308.02321">pdf</a>, <a href="https://arxiv.org/format/2308.02321">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-024-46623-y">10.1038/s41467-024-46623-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimizing quantum gates towards the scale of logical qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">Paul V. Klimov</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Quintana%2C+C">Chris Quintana</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Dunsworth%2C+A">Andrew Dunsworth</a>, <a href="/search/quant-ph?searchtype=author&query=Satzinger%2C+K+J">Kevin J. Satzinger</a>, <a href="/search/quant-ph?searchtype=author&query=Livingston%2C+W+P">William P. Livingston</a>, <a href="/search/quant-ph?searchtype=author&query=Sivak%2C+V">Volodymyr Sivak</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+M+Y">Murphy Y. Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yaxing Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chik%2C+D">Desmond Chik</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/quant-ph?searchtype=author&query=Erickson%2C+C">Catherine Erickson</a>, <a href="/search/quant-ph?searchtype=author&query=Dau%2C+A+G">Alejandro Grajales Dau</a>, <a href="/search/quant-ph?searchtype=author&query=Megrant%2C+A">Anthony Megrant</a>, <a href="/search/quant-ph?searchtype=author&query=Roushan%2C+P">Pedram Roushan</a>, <a href="/search/quant-ph?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</a>, <a href="/search/quant-ph?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/quant-ph?searchtype=author&query=Smelyanskiy%2C+V">Vadim Smelyanskiy</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Neven%2C+H">Hartmut Neven</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.02321v3-abstract-short" style="display: inline;"> A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quant… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02321v3-abstract-full').style.display = 'inline'; document.getElementById('2308.02321v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.02321v3-abstract-full" style="display: none;"> A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quantum gates from small to large processors without degrading performance often maps to non-convex, high-constraint, and time-dependent control optimization over an exponentially expanding configuration space. Here we report on a control optimization strategy that can scalably overcome the complexity of such problems. We demonstrate it by choreographing the frequency trajectories of 68 frequency-tunable superconducting qubits to execute single- and two-qubit gates while mitigating computational errors. When combined with a comprehensive model of physical errors across our processor, the strategy suppresses physical error rates by $\sim3.7\times$ compared with the case of no optimization. Furthermore, it is projected to achieve a similar performance advantage on a distance-23 surface code logical qubit with 1057 physical qubits. Our control optimization strategy solves a generic scaling challenge in a way that can be adapted to a variety of quantum operations, algorithms, and computing architectures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02321v3-abstract-full').style.display = 'none'; document.getElementById('2308.02321v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 15, 2442 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.02079">arXiv:2308.02079</a> <span> [<a href="https://arxiv.org/pdf/2308.02079">pdf</a>, <a href="https://arxiv.org/format/2308.02079">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.132.100603">10.1103/PhysRevLett.132.100603 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Model-based Optimization of Superconducting Qubit Readout </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Khezri%2C+M">Mostafa Khezri</a>, <a href="/search/quant-ph?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Satzinger%2C+K+J">Kevin J. Satzinger</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Erickson%2C+C">Catherine Erickson</a>, <a href="/search/quant-ph?searchtype=author&query=Lester%2C+B+J">Brian J. Lester</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+K+C">Kevin C. Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</a>, <a href="/search/quant-ph?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">Paul V. Klimov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.02079v2-abstract-short" style="display: inline;"> Measurement is an essential component of quantum algorithms, and for superconducting qubits it is often the most error prone. Here, we demonstrate model-based readout optimization achieving low measurement errors while avoiding detrimental side-effects. For simultaneous and mid-circuit measurements across 17 qubits, we observe 1.5% error per qubit with a 500ns end-to-end duration and minimal exces… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02079v2-abstract-full').style.display = 'inline'; document.getElementById('2308.02079v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.02079v2-abstract-full" style="display: none;"> Measurement is an essential component of quantum algorithms, and for superconducting qubits it is often the most error prone. Here, we demonstrate model-based readout optimization achieving low measurement errors while avoiding detrimental side-effects. For simultaneous and mid-circuit measurements across 17 qubits, we observe 1.5% error per qubit with a 500ns end-to-end duration and minimal excess reset error from residual resonator photons. We also suppress measurement-induced state transitions achieving a leakage rate limited by natural heating. This technique can scale to hundreds of qubits and be used to enhance the performance of error-correcting codes and near-term applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02079v2-abstract-full').style.display = 'none'; document.getElementById('2308.02079v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.09333">arXiv:2306.09333</a> <span> [<a href="https://arxiv.org/pdf/2306.09333">pdf</a>, <a href="https://arxiv.org/format/2306.09333">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.adi7877">10.1126/science.adi7877 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dynamics of magnetization at infinite temperature in a Heisenberg spin chain </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T">Trond Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Samajdar%2C+R">Rhine Samajdar</a>, <a href="/search/quant-ph?searchtype=author&query=Petukhov%2C+A">Andre Petukhov</a>, <a href="/search/quant-ph?searchtype=author&query=Hoke%2C+J">Jesse Hoke</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Drozdov%2C+I">Ilya Drozdov</a>, <a href="/search/quant-ph?searchtype=author&query=Erickson%2C+C">Catherine Erickson</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P">Paul Klimov</a>, <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Morvan%2C+A">Alexis Morvan</a>, <a href="/search/quant-ph?searchtype=author&query=Neeley%2C+M">Matthew Neeley</a>, <a href="/search/quant-ph?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Allen%2C+R">Richard Allen</a>, <a href="/search/quant-ph?searchtype=author&query=Anderson%2C+K">Kyle Anderson</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J">Joseph Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">A. Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a> , et al. (156 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.09333v2-abstract-short" style="display: inline;"> Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the 1D Heisenberg model were conjectured to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we study the probability distributio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.09333v2-abstract-full').style.display = 'inline'; document.getElementById('2306.09333v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.09333v2-abstract-full" style="display: none;"> Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the 1D Heisenberg model were conjectured to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we study the probability distribution, $P(\mathcal{M})$, of the magnetization transferred across the chain's center. The first two moments of $P(\mathcal{M})$ show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments rule out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide key insights into universal behavior in quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.09333v2-abstract-full').style.display = 'none'; document.getElementById('2306.09333v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 384, 48-53 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.17816">arXiv:2305.17816</a> <span> [<a href="https://arxiv.org/pdf/2305.17816">pdf</a>, <a href="https://arxiv.org/format/2305.17816">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> Josephson parametric amplifier with Chebyshev gain profile and high saturation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kaufman%2C+R">Ryan Kaufman</a>, <a href="/search/quant-ph?searchtype=author&query=White%2C+T">Theodore White</a>, <a href="/search/quant-ph?searchtype=author&query=Dykman%2C+M+I">Mark I. Dykman</a>, <a href="/search/quant-ph?searchtype=author&query=Iorio%2C+A">Andrea Iorio</a>, <a href="/search/quant-ph?searchtype=author&query=Stirling%2C+G">George Stirling</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Faoro%2C+L">Lara Faoro</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/quant-ph?searchtype=author&query=Gasca%2C+R">Robert Gasca</a>, <a href="/search/quant-ph?searchtype=author&query=Naaman%2C+O">Ofer Naaman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.17816v1-abstract-short" style="display: inline;"> We demonstrate a Josephson parametric amplifier design with a band-pass impedance matching network based on a third-order Chebyshev prototype. We measured eight amplifiers operating at 4.6 GHz that exhibit gains of 20 dB with less than 1 dB gain ripple and up to 500 MHz bandwidth. The amplifiers further achieve high output saturation powers around -73 dBm based on the use of rf-SQUID arrays as the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17816v1-abstract-full').style.display = 'inline'; document.getElementById('2305.17816v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.17816v1-abstract-full" style="display: none;"> We demonstrate a Josephson parametric amplifier design with a band-pass impedance matching network based on a third-order Chebyshev prototype. We measured eight amplifiers operating at 4.6 GHz that exhibit gains of 20 dB with less than 1 dB gain ripple and up to 500 MHz bandwidth. The amplifiers further achieve high output saturation powers around -73 dBm based on the use of rf-SQUID arrays as their nonlinear element. We characterize the system readout efficiency and its signal-to-noise ratio near saturation using a Sycamore processor, finding the data consistent with near quantum limited noise performance of the amplifiers. In addition, we measure the amplifiers' intermodulation distortion in two-tone experiments as a function of input power and inter-tone detuning, and observe excess distortion at small detuning with a pronounced dip as a function of signal power, which we interpret in terms of power-dependent dielectric losses. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17816v1-abstract-full').style.display = 'none'; document.getElementById('2305.17816v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 10 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.13878">arXiv:2304.13878</a> <span> [<a href="https://arxiv.org/pdf/2304.13878">pdf</a>, <a href="https://arxiv.org/format/2304.13878">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.adh9932">10.1126/science.adh9932 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stable Quantum-Correlated Many Body States through Engineered Dissipation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">X. Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Michailidis%2C+A+A">A. A. Michailidis</a>, <a href="/search/quant-ph?searchtype=author&query=Shabani%2C+S">S. Shabani</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+K+C">K. C. Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">P. V. Klimov</a>, <a href="/search/quant-ph?searchtype=author&query=Lloyd%2C+J">J. Lloyd</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+E">E. Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">R. Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">I. Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">T. I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">F. Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">K. Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">A. Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">J. Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">J. C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">G. Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">A. Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">J. Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">L. Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">M. Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">B. B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">D. A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">T. Burger</a> , et al. (142 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.13878v2-abstract-short" style="display: inline;"> Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13878v2-abstract-full').style.display = 'inline'; document.getElementById('2304.13878v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.13878v2-abstract-full" style="display: none;"> Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13878v2-abstract-full').style.display = 'none'; document.getElementById('2304.13878v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 383, 1332-1337 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.11119">arXiv:2304.11119</a> <span> [<a href="https://arxiv.org/pdf/2304.11119">pdf</a>, <a href="https://arxiv.org/format/2304.11119">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-024-07998-6">10.1038/s41586-024-07998-6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phase transition in Random Circuit Sampling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Morvan%2C+A">A. Morvan</a>, <a href="/search/quant-ph?searchtype=author&query=Villalonga%2C+B">B. Villalonga</a>, <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">X. Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Mandr%C3%A0%2C+S">S. Mandr脿</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">P. V. Klimov</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">S. Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Erickson%2C+C">C. Erickson</a>, <a href="/search/quant-ph?searchtype=author&query=Drozdov%2C+I+K">I. K. Drozdov</a>, <a href="/search/quant-ph?searchtype=author&query=Chau%2C+J">J. Chau</a>, <a href="/search/quant-ph?searchtype=author&query=Laun%2C+G">G. Laun</a>, <a href="/search/quant-ph?searchtype=author&query=Movassagh%2C+R">R. Movassagh</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">A. Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Brand%C3%A3o%2C+L+T+A+N">L. T. A. N. Brand茫o</a>, <a href="/search/quant-ph?searchtype=author&query=Peralta%2C+R">R. Peralta</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">D. Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">R. Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Allen%2C+R">R. Allen</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">T. I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Anderson%2C+K">K. Anderson</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">F. Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">K. Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">J. Atalaya</a> , et al. (160 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.11119v2-abstract-short" style="display: inline;"> Undesired coupling to the surrounding environment destroys long-range correlations on quantum processors and hinders the coherent evolution in the nominally available computational space. This incoherent noise is an outstanding challenge to fully leverage the computation power of near-term quantum processors. It has been shown that benchmarking Random Circuit Sampling (RCS) with Cross-Entropy Benc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11119v2-abstract-full').style.display = 'inline'; document.getElementById('2304.11119v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.11119v2-abstract-full" style="display: none;"> Undesired coupling to the surrounding environment destroys long-range correlations on quantum processors and hinders the coherent evolution in the nominally available computational space. This incoherent noise is an outstanding challenge to fully leverage the computation power of near-term quantum processors. It has been shown that benchmarking Random Circuit Sampling (RCS) with Cross-Entropy Benchmarking (XEB) can provide a reliable estimate of the effective size of the Hilbert space coherently available. The extent to which the presence of noise can trivialize the outputs of a given quantum algorithm, i.e. making it spoofable by a classical computation, is an unanswered question. Here, by implementing an RCS algorithm we demonstrate experimentally that there are two phase transitions observable with XEB, which we explain theoretically with a statistical model. The first is a dynamical transition as a function of the number of cycles and is the continuation of the anti-concentration point in the noiseless case. The second is a quantum phase transition controlled by the error per cycle; to identify it analytically and experimentally, we create a weak link model which allows varying the strength of noise versus coherent evolution. Furthermore, by presenting an RCS experiment with 67 qubits at 32 cycles, we demonstrate that the computational cost of our experiment is beyond the capabilities of existing classical supercomputers, even when accounting for the inevitable presence of noise. Our experimental and theoretical work establishes the existence of transitions to a stable computationally complex phase that is reachable with current quantum processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11119v2-abstract-full').style.display = 'none'; document.getElementById('2304.11119v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 634, 328-333 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.04792">arXiv:2303.04792</a> <span> [<a href="https://arxiv.org/pdf/2303.04792">pdf</a>, <a href="https://arxiv.org/format/2303.04792">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-023-06505-7">10.1038/s41586-023-06505-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement-induced entanglement and teleportation on a noisy quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hoke%2C+J+C">Jesse C. Hoke</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chiaro%2C+B">Ben Chiaro</a> , et al. (138 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.04792v2-abstract-short" style="display: inline;"> Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter the "arrow of time" that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time that go beyond established paradigms for characterizing phases, either in or out… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.04792v2-abstract-full').style.display = 'inline'; document.getElementById('2303.04792v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.04792v2-abstract-full" style="display: none;"> Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter the "arrow of time" that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time that go beyond established paradigms for characterizing phases, either in or out of equilibrium. On present-day NISQ processors, the experimental realization of this physics is challenging due to noise, hardware limitations, and the stochastic nature of quantum measurement. Here we address each of these experimental challenges and investigate measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping, to avoid mid-circuit measurement and access different manifestations of the underlying phases -- from entanglement scaling to measurement-induced teleportation -- in a unified way. We obtain finite-size signatures of a phase transition with a decoding protocol that correlates the experimental measurement record with classical simulation data. The phases display sharply different sensitivity to noise, which we exploit to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realize measurement-induced physics at scales that are at the limits of current NISQ processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.04792v2-abstract-full').style.display = 'none'; document.getElementById('2303.04792v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 622, 481-486 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.05097">arXiv:2212.05097</a> <span> [<a href="https://arxiv.org/pdf/2212.05097">pdf</a>, <a href="https://arxiv.org/format/2212.05097">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.20.054008">10.1103/PhysRevApplied.20.054008 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement-Induced State Transitions in a Superconducting Qubit: Within the Rotating Wave Approximation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Khezri%2C+M">Mostafa Khezri</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Miao%2C+K+C">Kevin C. Miao</a>, <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=White%2C+T">Theodore White</a>, <a href="/search/quant-ph?searchtype=author&query=Naaman%2C+O">Ofer Naaman</a>, <a href="/search/quant-ph?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/quant-ph?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Smelyanskiy%2C+V">Vadim Smelyanskiy</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.05097v2-abstract-short" style="display: inline;"> Superconducting qubits typically use a dispersive readout scheme, where a resonator is coupled to a qubit such that its frequency is qubit-state dependent. Measurement is performed by driving the resonator, where the transmitted resonator field yields information about the resonator frequency and thus the qubit state. Ideally, we could use arbitrarily strong resonator drives to achieve a target si… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.05097v2-abstract-full').style.display = 'inline'; document.getElementById('2212.05097v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.05097v2-abstract-full" style="display: none;"> Superconducting qubits typically use a dispersive readout scheme, where a resonator is coupled to a qubit such that its frequency is qubit-state dependent. Measurement is performed by driving the resonator, where the transmitted resonator field yields information about the resonator frequency and thus the qubit state. Ideally, we could use arbitrarily strong resonator drives to achieve a target signal-to-noise ratio in the shortest possible time. However, experiments have shown that when the average resonator photon number exceeds a certain threshold, the qubit is excited out of its computational subspace in a process we refer to as a measurement-induced state transition (MIST). These transitions degrade readout fidelity, and constitute leakage which precludes further operation of the qubit in, for example, error correction. Here we study these transitions experimentally with a transmon qubit by measuring their dependence on qubit frequency, average resonator photon number, and qubit state, in the regime where the resonator frequency is lower than the qubit frequency. We observe signatures of resonant transitions between levels in the coupled qubit-resonator system that exhibit noisy behavior when measured repeatedly in time. We provide a semi-classical model of these transitions based on the rotating wave approximation and use it to predict the onset of state transitions in our experiments. Our results suggest the transmon is excited to levels near the top of its cosine potential following a state transition, where the charge dispersion of higher transmon levels explains the observed noisy behavior of state transitions. Moreover, we show that occupation in these higher energy levels poses a major challenge for fast qubit reset. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.05097v2-abstract-full').style.display = 'none'; document.getElementById('2212.05097v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 20, 054008 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.04728">arXiv:2211.04728</a> <span> [<a href="https://arxiv.org/pdf/2211.04728">pdf</a>, <a href="https://arxiv.org/format/2211.04728">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-023-02226-w">10.1038/s41567-023-02226-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Overcoming leakage in scalable quantum error correction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Miao%2C+K+C">Kevin C. Miao</a>, <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Kafri%2C+D">Dvir Kafri</a>, <a href="/search/quant-ph?searchtype=author&query=Pryadko%2C+L+P">Leonid P. Pryadko</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Satzinger%2C+K+J">Kevin J. Satzinger</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">Paul V. Klimov</a>, <a href="/search/quant-ph?searchtype=author&query=Quintana%2C+C">Chris Quintana</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Anderson%2C+K">Kyle Anderson</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a> , et al. (92 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.04728v1-abstract-short" style="display: inline;"> Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.04728v1-abstract-full').style.display = 'inline'; document.getElementById('2211.04728v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.04728v1-abstract-full" style="display: none;"> Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path towards fault-tolerant quantum computation. Here, we demonstrate the execution of a distance-3 surface code and distance-21 bit-flip code on a Sycamore quantum processor where leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a ten-fold reduction in steady-state leakage population on the data qubits encoding the logical state and an average leakage population of less than $1 \times 10^{-3}$ throughout the entire device. The leakage removal process itself efficiently returns leakage population back to the computational basis, and adding it to a code circuit prevents leakage from inducing correlated error across cycles, restoring a fundamental assumption of QEC. With this demonstration that leakage can be contained, we resolve a key challenge for practical QEC at scale. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.04728v1-abstract-full').style.display = 'none'; document.getElementById('2211.04728v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main text: 7 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.10799">arXiv:2210.10799</a> <span> [<a href="https://arxiv.org/pdf/2210.10799">pdf</a>, <a href="https://arxiv.org/format/2210.10799">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-023-02240-y">10.1038/s41567-023-02240-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Purification-based quantum error mitigation of pair-correlated electron simulations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=O%27Brien%2C+T+E">T. E. O'Brien</a>, <a href="/search/quant-ph?searchtype=author&query=Anselmetti%2C+G">G. Anselmetti</a>, <a href="/search/quant-ph?searchtype=author&query=Gkritsis%2C+F">F. Gkritsis</a>, <a href="/search/quant-ph?searchtype=author&query=Elfving%2C+V+E">V. E. Elfving</a>, <a href="/search/quant-ph?searchtype=author&query=Polla%2C+S">S. Polla</a>, <a href="/search/quant-ph?searchtype=author&query=Huggins%2C+W+J">W. J. Huggins</a>, <a href="/search/quant-ph?searchtype=author&query=Oumarou%2C+O">O. Oumarou</a>, <a href="/search/quant-ph?searchtype=author&query=Kechedzhi%2C+K">K. Kechedzhi</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">D. Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">R. Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">I. Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Allen%2C+R">R. Allen</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">T. I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Anderson%2C+K">K. Anderson</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">F. Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">K. Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">A. Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">J. Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">D. Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">J. C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Boixo%2C+S">S. Boixo</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">G. Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">A. Bourassa</a> , et al. (151 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.10799v1-abstract-short" style="display: inline;"> An important measure of the development of quantum computing platforms has been the simulation of increasingly complex physical systems. Prior to fault-tolerant quantum computing, robust error mitigation strategies are necessary to continue this growth. Here, we study physical simulation within the seniority-zero electron pairing subspace, which affords both a computational stepping stone to a ful… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.10799v1-abstract-full').style.display = 'inline'; document.getElementById('2210.10799v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.10799v1-abstract-full" style="display: none;"> An important measure of the development of quantum computing platforms has been the simulation of increasingly complex physical systems. Prior to fault-tolerant quantum computing, robust error mitigation strategies are necessary to continue this growth. Here, we study physical simulation within the seniority-zero electron pairing subspace, which affords both a computational stepping stone to a fully correlated model, and an opportunity to validate recently introduced ``purification-based'' error-mitigation strategies. We compare the performance of error mitigation based on doubling quantum resources in time (echo verification) or in space (virtual distillation), on up to $20$ qubits of a superconducting qubit quantum processor. We observe a reduction of error by one to two orders of magnitude below less sophisticated techniques (e.g. post-selection); the gain from error mitigation is seen to increase with the system size. Employing these error mitigation strategies enables the implementation of the largest variational algorithm for a correlated chemistry system to-date. Extrapolating performance from these results allows us to estimate minimum requirements for a beyond-classical simulation of electronic structure. We find that, despite the impressive gains from purification-based error mitigation, significant hardware improvements will be required for classically intractable variational chemistry simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.10799v1-abstract-full').style.display = 'none'; document.getElementById('2210.10799v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 13 page supplementary material, 12 figures. Experimental data available at https://doi.org/10.5281/zenodo.7225821</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Phys. (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.10255">arXiv:2210.10255</a> <span> [<a href="https://arxiv.org/pdf/2210.10255">pdf</a>, <a href="https://arxiv.org/format/2210.10255">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> </div> </div> <p class="title is-5 mathjax"> Non-Abelian braiding of graph vertices in a superconducting processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Lensky%2C+Y+D">Yuri D. Lensky</a>, <a href="/search/quant-ph?searchtype=author&query=Kechedzhi%2C+K">Kostyantyn Kechedzhi</a>, <a href="/search/quant-ph?searchtype=author&query=Drozdov%2C+I">Ilya Drozdov</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Morvan%2C+A">Alexis Morvan</a>, <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Allen%2C+R">Richard Allen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a> , et al. (144 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.10255v2-abstract-short" style="display: inline;"> Indistinguishability of particles is a fundamental principle of quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, and Abelian anyons - this principle guarantees that the braiding of identical particles leaves the system unchanged. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.10255v2-abstract-full').style.display = 'inline'; document.getElementById('2210.10255v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.10255v2-abstract-full" style="display: none;"> Indistinguishability of particles is a fundamental principle of quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, and Abelian anyons - this principle guarantees that the braiding of identical particles leaves the system unchanged. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well developed mathematical description of non-Abelian anyons and numerous theoretical proposals, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. While efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasi-particles, superconducting quantum processors allow for directly manipulating the many-body wavefunction via unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons, we implement a generalized stabilizer code and unitary protocol to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of employing the anyons for quantum computation and utilize braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and - through the future inclusion of error correction to achieve topological protection - could open a path toward fault-tolerant quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.10255v2-abstract-full').style.display = 'none'; document.getElementById('2210.10255v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.07757">arXiv:2209.07757</a> <span> [<a href="https://arxiv.org/pdf/2209.07757">pdf</a>, <a href="https://arxiv.org/format/2209.07757">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0127375">10.1063/5.0127375 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Readout of a quantum processor with high dynamic range Josephson parametric amplifiers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/quant-ph?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/quant-ph?searchtype=author&query=Sterling%2C+G">George Sterling</a>, <a href="/search/quant-ph?searchtype=author&query=Korotkov%2C+A">Alexander Korotkov</a>, <a href="/search/quant-ph?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chiaro%2C+B">Ben Chiaro</a>, <a href="/search/quant-ph?searchtype=author&query=Cogan%2C+J">Josh Cogan</a>, <a href="/search/quant-ph?searchtype=author&query=Collins%2C+R">Roberto Collins</a>, <a href="/search/quant-ph?searchtype=author&query=Crook%2C+A+L">Alexander L. Crook</a>, <a href="/search/quant-ph?searchtype=author&query=Curtin%2C+B">Ben Curtin</a> , et al. (69 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.07757v2-abstract-short" style="display: inline;"> We demonstrate a high dynamic range Josephson parametric amplifier (JPA) in which the active nonlinear element is implemented using an array of rf-SQUIDs. The device is matched to the 50 $惟$ environment with a Klopfenstein-taper impedance transformer and achieves a bandwidth of 250-300 MHz, with input saturation powers up to -95 dBm at 20 dB gain. A 54-qubit Sycamore processor was used to benchmar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07757v2-abstract-full').style.display = 'inline'; document.getElementById('2209.07757v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.07757v2-abstract-full" style="display: none;"> We demonstrate a high dynamic range Josephson parametric amplifier (JPA) in which the active nonlinear element is implemented using an array of rf-SQUIDs. The device is matched to the 50 $惟$ environment with a Klopfenstein-taper impedance transformer and achieves a bandwidth of 250-300 MHz, with input saturation powers up to -95 dBm at 20 dB gain. A 54-qubit Sycamore processor was used to benchmark these devices, providing a calibration for readout power, an estimate of amplifier added noise, and a platform for comparison against standard impedance matched parametric amplifiers with a single dc-SQUID. We find that the high power rf-SQUID array design has no adverse effect on system noise, readout fidelity, or qubit dephasing, and we estimate an upper bound on amplifier added noise at 1.6 times the quantum limit. Lastly, amplifiers with this design show no degradation in readout fidelity due to gain compression, which can occur in multi-tone multiplexed readout with traditional JPAs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07757v2-abstract-full').style.display = 'none'; document.getElementById('2209.07757v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 122, 014001 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.06431">arXiv:2207.06431</a> <span> [<a href="https://arxiv.org/pdf/2207.06431">pdf</a>, <a href="https://arxiv.org/format/2207.06431">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Suppressing quantum errors by scaling a surface code logical qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">Igor Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Allen%2C+R">Richard Allen</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Basso%2C+J">Joao Basso</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Boixo%2C+S">Sergio Boixo</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a> , et al. (132 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.06431v2-abstract-short" style="display: inline;"> Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.06431v2-abstract-full').style.display = 'inline'; document.getElementById('2207.06431v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.06431v2-abstract-full" style="display: none;"> Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.06431v2-abstract-full').style.display = 'none'; document.getElementById('2207.06431v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main text: 6 pages, 4 figures. v2: Update author list, references, Fig. S12, Table IV</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.02938">arXiv:2207.02938</a> <span> [<a href="https://arxiv.org/pdf/2207.02938">pdf</a>, <a href="https://arxiv.org/format/2207.02938">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-023-00711-x">10.1038/s41534-023-00711-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Extensive characterization of a family of efficient three-qubit gates at the coherence limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Warren%2C+C+W">Christopher W. Warren</a>, <a href="/search/quant-ph?searchtype=author&query=Fern%C3%A1ndez-Pend%C3%A1s%2C+J">Jorge Fern谩ndez-Pend谩s</a>, <a href="/search/quant-ph?searchtype=author&query=Ahmed%2C+S">Shahnawaz Ahmed</a>, <a href="/search/quant-ph?searchtype=author&query=Abad%2C+T">Tahereh Abad</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bizn%C3%A1rov%C3%A1%2C+J">Janka Bizn谩rov谩</a>, <a href="/search/quant-ph?searchtype=author&query=Debnath%2C+K">Kamanasish Debnath</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+X">Xiu Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Kri%C5%BEan%2C+C">Christian Kri啪an</a>, <a href="/search/quant-ph?searchtype=author&query=Osman%2C+A">Amr Osman</a>, <a href="/search/quant-ph?searchtype=author&query=Roudsari%2C+A+F">Anita Fadavi Roudsari</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Johansson%2C+G">G枚ran Johansson</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">Giovanna Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.02938v1-abstract-short" style="display: inline;"> While all quantum algorithms can be expressed in terms of single-qubit and two-qubit gates, more expressive gate sets can help reduce the algorithmic depth. This is important in the presence of gate errors, especially those due to decoherence. Using superconducting qubits, we have implemented a three-qubit gate by simultaneously applying two-qubit operations, thereby realizing a three-body interac… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.02938v1-abstract-full').style.display = 'inline'; document.getElementById('2207.02938v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.02938v1-abstract-full" style="display: none;"> While all quantum algorithms can be expressed in terms of single-qubit and two-qubit gates, more expressive gate sets can help reduce the algorithmic depth. This is important in the presence of gate errors, especially those due to decoherence. Using superconducting qubits, we have implemented a three-qubit gate by simultaneously applying two-qubit operations, thereby realizing a three-body interaction. This method straightforwardly extends to other quantum hardware architectures, requires only a "firmware" upgrade to implement, and is faster than its constituent two-qubit gates. The three-qubit gate represents an entire family of operations, creating flexibility in quantum-circuit compilation. We demonstrate a gate fidelity of $97.90\%$, which is near the coherence limit of our device. We then generate two classes of entangled states, the GHZ and W states, by applying the new gate only once; in comparison, decompositions into the standard gate set would have a two-qubit gate depth of two and three, respectively. Finally, we combine characterization methods and analyze the experimental and statistical errors on the fidelity of the gates and of the target states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.02938v1-abstract-full').style.display = 'none'; document.getElementById('2207.02938v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Inf 9, 44 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.05254">arXiv:2206.05254</a> <span> [<a href="https://arxiv.org/pdf/2206.05254">pdf</a>, <a href="https://arxiv.org/format/2206.05254">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-022-05348-y">10.1038/s41586-022-05348-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Formation of robust bound states of interacting microwave photons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Morvan%2C+A">Alexis Morvan</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/quant-ph?searchtype=author&query=Petukhov%2C+A">Andre Petukhov</a>, <a href="/search/quant-ph?searchtype=author&query=Kechedzhi%2C+K">Kostyantyn Kechedzhi</a>, <a href="/search/quant-ph?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Basso%2C+J">Joao Basso</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burger%2C+T">Tim Burger</a> , et al. (125 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.05254v3-abstract-short" style="display: inline;"> Systems of correlated particles appear in many fields of science and represent some of the most intractable puzzles in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles. The lack of general solutions for the 3-body problem and acceptable theory for strongly cor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.05254v3-abstract-full').style.display = 'inline'; document.getElementById('2206.05254v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.05254v3-abstract-full" style="display: none;"> Systems of correlated particles appear in many fields of science and represent some of the most intractable puzzles in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles. The lack of general solutions for the 3-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multi-particle bound states. In a ring of 24 superconducting qubits, we develop a high fidelity parameterizable fSim gate that we use to implement the periodic quantum circuit of the spin-1/2 XXZ model, an archetypal model of interaction. By placing microwave photons in adjacent qubit sites, we study the propagation of these excitations and observe their bound nature for up to 5 photons. We devise a phase sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the common wisdom that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.05254v3-abstract-full').style.display = 'none'; document.getElementById('2206.05254v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages + 15 pages supplements</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 612, 240-245 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.15253">arXiv:2205.15253</a> <span> [<a href="https://arxiv.org/pdf/2205.15253">pdf</a>, <a href="https://arxiv.org/ps/2205.15253">ps</a>, <a href="https://arxiv.org/format/2205.15253">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0101398">10.1063/5.0101398 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement and control of a superconducting quantum processor with a fully-integrated radio-frequency system on a chip </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Thol%C3%A9n%2C+M+O">Mats O. Thol茅n</a>, <a href="/search/quant-ph?searchtype=author&query=Borgani%2C+R">Riccardo Borgani</a>, <a href="/search/quant-ph?searchtype=author&query=Di+Carlo%2C+G+R">Giuseppe Ruggero Di Carlo</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Kri%C5%BEan%2C+C">Christian Kri啪an</a>, <a href="/search/quant-ph?searchtype=author&query=Kudra%2C+M">Marina Kudra</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">Giovanna Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Gasparinetti%2C+S">Simone Gasparinetti</a>, <a href="/search/quant-ph?searchtype=author&query=Haviland%2C+D+B">David B. Haviland</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2205.15253v3-abstract-short" style="display: inline;"> We describe a digital microwave platform called Presto, designed for measurement and control of multiple quantum bits (qubits) and based on the third-generation radio-frequency system on a chip. Presto uses direct digital synthesis to create signals up to 9 GHz on 16 synchronous output ports, while synchronously analyzing response on 16 input ports. Presto has 16 DC-bias outputs, 4 inputs and 4 ou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.15253v3-abstract-full').style.display = 'inline'; document.getElementById('2205.15253v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.15253v3-abstract-full" style="display: none;"> We describe a digital microwave platform called Presto, designed for measurement and control of multiple quantum bits (qubits) and based on the third-generation radio-frequency system on a chip. Presto uses direct digital synthesis to create signals up to 9 GHz on 16 synchronous output ports, while synchronously analyzing response on 16 input ports. Presto has 16 DC-bias outputs, 4 inputs and 4 outputs for digital triggers or markers, and two continuous-wave outputs for synthesizing frequencies up to 15 GHz. Scaling to a large number of qubits is enabled through deterministic synchronization of multiple Presto units. A Python application programming interface configures a firmware for synthesis and analysis of pulses, coordinated by an event sequencer. The analysis integrates template matching (matched filtering) and low-latency (184 - 254 ns) feedback to enable a wide range of multi-qubit experiments. We demonstrate Presto's capabilities with experiments on a sample consisting of two superconducting qubits connected via a flux-tunable coupler. We show single-shot readout and active reset of a single qubit; randomized benchmarking of single-qubit gates showing 99.972% fidelity, limited by the coherence time of the qubit; and calibration of a two-qubit iSWAP gate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.15253v3-abstract-full').style.display = 'none'; document.getElementById('2205.15253v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">v3: peer reviewed, accepted manuscript; v2: correct theoretical gate fidelity in Sec. III C</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Review of Scientific Instruments 93, 104711 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.11372">arXiv:2204.11372</a> <span> [<a href="https://arxiv.org/pdf/2204.11372">pdf</a>, <a href="https://arxiv.org/format/2204.11372">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.abq5769">10.1126/science.abq5769 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Noise-resilient Edge Modes on a Chain of Superconducting Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Sonner%2C+M">Michael Sonner</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+M+Y">Murphy Yuezhen Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+K+W">Kenneth W. Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Foxen%2C+B">Brooks Foxen</a>, <a href="/search/quant-ph?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">Igor Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Basso%2C+J">Joao Basso</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a> , et al. (103 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.11372v2-abstract-short" style="display: inline;"> Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model which exhibits non-local Majorana edge modes (MEMs) with $\mathbb{Z}_2$ parity symmetry. Remarkably, we find that any multi-qub… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.11372v2-abstract-full').style.display = 'inline'; document.getElementById('2204.11372v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.11372v2-abstract-full" style="display: none;"> Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model which exhibits non-local Majorana edge modes (MEMs) with $\mathbb{Z}_2$ parity symmetry. Remarkably, we find that any multi-qubit Pauli operator overlapping with the MEMs exhibits a uniform late-time decay rate comparable to single-qubit relaxation rates, irrespective of its size or composition. This characteristic allows us to accurately reconstruct the exponentially localized spatial profiles of the MEMs. Furthermore, the MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism. Our work elucidates the complex interplay between noise and symmetry-protected edge modes in a solid-state environment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.11372v2-abstract-full').style.display = 'none'; document.getElementById('2204.11372v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 378, 785 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.11358">arXiv:2108.11358</a> <span> [<a href="https://arxiv.org/pdf/2108.11358">pdf</a>, <a href="https://arxiv.org/format/2108.11358">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.2.040348">10.1103/PRXQuantum.2.040348 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fast multi-qubit gates through simultaneous two-qubit gates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gu%2C+X">Xiu Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Fern%C3%A1ndez-Pend%C3%A1s%2C+J">Jorge Fern谩ndez-Pend谩s</a>, <a href="/search/quant-ph?searchtype=author&query=Vikst%C3%A5l%2C+P">Pontus Vikst氓l</a>, <a href="/search/quant-ph?searchtype=author&query=Abad%2C+T">Tahereh Abad</a>, <a href="/search/quant-ph?searchtype=author&query=Warren%2C+C">Christopher Warren</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">Giovanna Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Shumeiko%2C+V">Vitaly Shumeiko</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=Johansson%2C+G">G枚ran Johansson</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.11358v1-abstract-short" style="display: inline;"> Near-term quantum computers are limited by the decoherence of qubits to only being able to run low-depth quantum circuits with acceptable fidelity. This severely restricts what quantum algorithms can be compiled and implemented on such devices. One way to overcome these limitations is to expand the available gate set from single- and two-qubit gates to multi-qubit gates, which entangle three or mo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.11358v1-abstract-full').style.display = 'inline'; document.getElementById('2108.11358v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.11358v1-abstract-full" style="display: none;"> Near-term quantum computers are limited by the decoherence of qubits to only being able to run low-depth quantum circuits with acceptable fidelity. This severely restricts what quantum algorithms can be compiled and implemented on such devices. One way to overcome these limitations is to expand the available gate set from single- and two-qubit gates to multi-qubit gates, which entangle three or more qubits in a single step. Here, we show that such multi-qubit gates can be realized by the simultaneous application of multiple two-qubit gates to a group of qubits where at least one qubit is involved in two or more of the two-qubit gates. Multi-qubit gates implemented in this way are as fast as, or sometimes even faster than, the constituent two-qubit gates. Furthermore, these multi-qubit gates do not require any modification of the quantum processor, but are ready to be used in current quantum-computing platforms. We demonstrate this idea for two specific cases: simultaneous controlled-Z gates and simultaneous iSWAP gates. We show how the resulting multi-qubit gates relate to other well-known multi-qubit gates and demonstrate through numerical simulations that they would work well in available quantum hardware, reaching gate fidelities well above 99 %. We also present schemes for using these simultaneous two-qubit gates to swiftly create large entangled states like Dicke and Greenberg-Horne-Zeilinger states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.11358v1-abstract-full').style.display = 'none'; document.getElementById('2108.11358v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 14 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 2, 040348 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.13571">arXiv:2107.13571</a> <span> [<a href="https://arxiv.org/pdf/2107.13571">pdf</a>, <a href="https://arxiv.org/format/2107.13571">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-021-04257-w">10.1038/s41586-021-04257-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of Time-Crystalline Eigenstate Order on a Quantum Processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</a>, <a href="/search/quant-ph?searchtype=author&query=Quintana%2C+C">Chris Quintana</a>, <a href="/search/quant-ph?searchtype=author&query=Greene%2C+A">Ami Greene</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Gross%2C+J">Jonathan Gross</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Basso%2C+J">Joao Basso</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Chiaro%2C+B">Benjamin Chiaro</a>, <a href="/search/quant-ph?searchtype=author&query=Collins%2C+R">Roberto Collins</a>, <a href="/search/quant-ph?searchtype=author&query=Courtney%2C+W">William Courtney</a>, <a href="/search/quant-ph?searchtype=author&query=Debroy%2C+D">Dripto Debroy</a> , et al. (80 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.13571v2-abstract-short" style="display: inline;"> Quantum many-body systems display rich phase structure in their low-temperature equilibrium states. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC). Concretely, dyn… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.13571v2-abstract-full').style.display = 'inline'; document.getElementById('2107.13571v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.13571v2-abstract-full" style="display: none;"> Quantum many-body systems display rich phase structure in their low-temperature equilibrium states. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC). Concretely, dynamical phases can be defined in periodically driven many-body localized systems via the concept of eigenstate order. In eigenstate-ordered phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, wherein few select states can mask typical behavior. Here we implement a continuous family of tunable CPHASE gates on an array of superconducting qubits to experimentally observe an eigenstate-ordered DTC. We demonstrate the characteristic spatiotemporal response of a DTC for generic initial states. Our work employs a time-reversal protocol that discriminates external decoherence from intrinsic thermalization, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. In addition, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to study non-equilibrium phases of matter on current quantum processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.13571v2-abstract-full').style.display = 'none'; document.getElementById('2107.13571v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 601, 531 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.12700">arXiv:2107.12700</a> <span> [<a href="https://arxiv.org/pdf/2107.12700">pdf</a>, <a href="https://arxiv.org/format/2107.12700">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PRXQuantum.3.020305">10.1103/PRXQuantum.3.020305 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nonequilibrium heat transport and work with a single artificial atom coupled to a waveguide: emission without external driving </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yong Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Lambert%2C+N">Neill Lambert</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a>, <a href="/search/quant-ph?searchtype=author&query=Funo%2C+K">Ken Funo</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Gasparinetti%2C+S">Simone Gasparinetti</a>, <a href="/search/quant-ph?searchtype=author&query=Nori%2C+F">Franco Nori</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.12700v1-abstract-short" style="display: inline;"> We observe the continuous emission of photons into a waveguide from a superconducting qubit without the application of an external drive. To explain this observation, we build a two-bath model where the qubit couples simultaneously to a cold bath (the waveguide) and a hot bath (a secondary environment). Our results show that the thermal-photon occupation of the hot bath is up to 0.14 photons, 35 t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.12700v1-abstract-full').style.display = 'inline'; document.getElementById('2107.12700v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.12700v1-abstract-full" style="display: none;"> We observe the continuous emission of photons into a waveguide from a superconducting qubit without the application of an external drive. To explain this observation, we build a two-bath model where the qubit couples simultaneously to a cold bath (the waveguide) and a hot bath (a secondary environment). Our results show that the thermal-photon occupation of the hot bath is up to 0.14 photons, 35 times larger than the cold waveguide, leading to nonequilibrium heat transport with a power of up to 132 zW, as estimated from the qubit emission spectrum. By adding more isolation between the sample output and the first cold amplifier in the output line, the heat transport is strongly suppressed. Our interpretation is that the hot bath may arise from active two-level systems being excited by noise from the output line. We also apply a coherent drive, and use the waveguide to measure thermodynamic work and heat, suggesting waveguide spectroscopy is a useful means to study quantum heat engines and refrigerators. Finally, based on the theoretical model, we propose how a similar setup can be used as a noise spectrometer which provides a new solution for calibrating the background noise of hybrid quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.12700v1-abstract-full').style.display = 'none'; document.getElementById('2107.12700v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 3, 020305 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.06852">arXiv:2107.06852</a> <span> [<a href="https://arxiv.org/pdf/2107.06852">pdf</a>, <a href="https://arxiv.org/format/2107.06852">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevX.12.031036">10.1103/PhysRevX.12.031036 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Extensible quantum simulation architecture based on atom-photon bound states in an array of high-impedance resonators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Scigliuzzo%2C+M">Marco Scigliuzzo</a>, <a href="/search/quant-ph?searchtype=author&query=Calaj%C3%B2%2C+G">Giuseppe Calaj貌</a>, <a href="/search/quant-ph?searchtype=author&query=Ciccarello%2C+F">Francesco Ciccarello</a>, <a href="/search/quant-ph?searchtype=author&query=Lozano%2C+D+P">Daniel Perez Lozano</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Scarlino%2C+P">Pasquale Scarlino</a>, <a href="/search/quant-ph?searchtype=author&query=Wallraff%2C+A">Andreas Wallraff</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+D">Darrick Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Gasparinetti%2C+S">Simone Gasparinetti</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.06852v1-abstract-short" style="display: inline;"> Engineering the electromagnetic environment of a quantum emitter gives rise to a plethora of exotic light-matter interactions. In particular, photonic lattices can seed long-lived atom-photon bound states inside photonic band gaps. Here we report on the concept and implementation of a novel microwave architecture consisting of an array of compact, high-impedance superconducting resonators forming… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.06852v1-abstract-full').style.display = 'inline'; document.getElementById('2107.06852v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.06852v1-abstract-full" style="display: none;"> Engineering the electromagnetic environment of a quantum emitter gives rise to a plethora of exotic light-matter interactions. In particular, photonic lattices can seed long-lived atom-photon bound states inside photonic band gaps. Here we report on the concept and implementation of a novel microwave architecture consisting of an array of compact, high-impedance superconducting resonators forming a 1 GHz-wide pass band, in which we have embedded two frequency-tuneable artificial atoms. We study the atom-field interaction and access previously unexplored coupling regimes, in both the single- and double-excitation subspace. In addition, we demonstrate coherent interactions between two atom-photon bound states, in both resonant and dispersive regimes, that are suitable for the implementation of SWAP and CZ two-qubit gates. The presented architecture holds promise for quantum simulation with tuneable-range interactions and photon transport experiments in nonlinear regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.06852v1-abstract-full').style.display = 'none'; document.getElementById('2107.06852v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.11234">arXiv:2105.11234</a> <span> [<a href="https://arxiv.org/pdf/2105.11234">pdf</a>, <a href="https://arxiv.org/format/2105.11234">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-021-00480-5">10.1038/s41534-021-00480-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum efficiency, purity and stability of a tunable, narrowband microwave single-photon source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yong Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Burnett%2C+J+J">Jonathan J. Burnett</a>, <a href="/search/quant-ph?searchtype=author&query=Suri%2C+B">Baladitya Suri</a>, <a href="/search/quant-ph?searchtype=author&query=Sathyamoorthy%2C+S+R">Sankar Raman Sathyamoorthy</a>, <a href="/search/quant-ph?searchtype=author&query=Nilsson%2C+H+R">Hampus Renberg Nilsson</a>, <a href="/search/quant-ph?searchtype=author&query=Scigliuzzo%2C+M">Marco Scigliuzzo</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=Johansson%2C+G">G枚ran Johansson</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.11234v1-abstract-short" style="display: inline;"> We demonstrate an on-demand source of microwave single photons with 71--99\% intrinsic quantum efficiency. The source is narrowband (300\unite{kHz}) and tuneable over a 600 MHz range around 5.2 GHz. Such a device is an important element in numerous quantum technologies and applications. The device consists of a superconducting transmon qubit coupled to the open end of a transmission line. A $蟺$-pu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11234v1-abstract-full').style.display = 'inline'; document.getElementById('2105.11234v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.11234v1-abstract-full" style="display: none;"> We demonstrate an on-demand source of microwave single photons with 71--99\% intrinsic quantum efficiency. The source is narrowband (300\unite{kHz}) and tuneable over a 600 MHz range around 5.2 GHz. Such a device is an important element in numerous quantum technologies and applications. The device consists of a superconducting transmon qubit coupled to the open end of a transmission line. A $蟺$-pulse excites the qubit, which subsequently rapidly emits a single photon into the transmission line. A cancellation pulse then suppresses the reflected $蟺$-pulse by 33.5 dB, resulting in 0.005 photons leaking into the photon emission channel. We verify strong antibunching of the emitted photon field and determine its Wigner function. Non-radiative decay and $1/f$ flux noise both affect the quantum efficiency. We also study the device stability over time and identify uncorrelated discrete jumps of the pure dephasing rate at different qubit frequencies on a time scale of hours, which we attribute to independent two-level system defects in the device dielectrics, dispersively coupled to the qubit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11234v1-abstract-full').style.display = 'none'; document.getElementById('2105.11234v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 7, 140 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.05219">arXiv:2104.05219</a> <span> [<a href="https://arxiv.org/pdf/2104.05219">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-021-01432-8">10.1038/s41567-021-01432-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Resolving catastrophic error bursts from cosmic rays in large arrays of superconducting qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Faoro%2C+L">Lara Faoro</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Dunsworth%2C+A">Andrew Dunsworth</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+T">Trent Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+S">Seon Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Fowler%2C+A">Austin Fowler</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Collins%2C+R">Roberto Collins</a>, <a href="/search/quant-ph?searchtype=author&query=Demura%2C+S">Sean Demura</a>, <a href="/search/quant-ph?searchtype=author&query=Derk%2C+A+R">Alan R. Derk</a>, <a href="/search/quant-ph?searchtype=author&query=Erickson%2C+C">Catherine Erickson</a>, <a href="/search/quant-ph?searchtype=author&query=Giustina%2C+M">Marissa Giustina</a>, <a href="/search/quant-ph?searchtype=author&query=Harrington%2C+S+D">Sean D. Harrington</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Jeffrey%2C+E">Evan Jeffrey</a>, <a href="/search/quant-ph?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">Paul V. Klimov</a> , et al. (28 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.05219v1-abstract-short" style="display: inline;"> Scalable quantum computing can become a reality with error correction, provided coherent qubits can be constructed in large arrays. The key premise is that physical errors can remain both small and sufficiently uncorrelated as devices scale, so that logical error rates can be exponentially suppressed. However, energetic impacts from cosmic rays and latent radioactivity violate both of these assump… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.05219v1-abstract-full').style.display = 'inline'; document.getElementById('2104.05219v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.05219v1-abstract-full" style="display: none;"> Scalable quantum computing can become a reality with error correction, provided coherent qubits can be constructed in large arrays. The key premise is that physical errors can remain both small and sufficiently uncorrelated as devices scale, so that logical error rates can be exponentially suppressed. However, energetic impacts from cosmic rays and latent radioactivity violate both of these assumptions. An impinging particle ionizes the substrate, radiating high energy phonons that induce a burst of quasiparticles, destroying qubit coherence throughout the device. High-energy radiation has been identified as a source of error in pilot superconducting quantum devices, but lacking a measurement technique able to resolve a single event in detail, the effect on large scale algorithms and error correction in particular remains an open question. Elucidating the physics involved requires operating large numbers of qubits at the same rapid timescales as in error correction, exposing the event's evolution in time and spread in space. Here, we directly observe high-energy rays impacting a large-scale quantum processor. We introduce a rapid space and time-multiplexed measurement method and identify large bursts of quasiparticles that simultaneously and severely limit the energy coherence of all qubits, causing chip-wide failure. We track the events from their initial localised impact to high error rates across the chip. Our results provide direct insights into the scale and dynamics of these damaging error bursts in large-scale devices, and highlight the necessity of mitigation to enable quantum computing to scale. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.05219v1-abstract-full').style.display = 'none'; document.getElementById('2104.05219v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics 18, 107-111 (Jan 2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.01180">arXiv:2104.01180</a> <span> [<a href="https://arxiv.org/pdf/2104.01180">pdf</a>, <a href="https://arxiv.org/format/2104.01180">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.abi8378">10.1126/science.abi8378 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Realizing topologically ordered states on a quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Satzinger%2C+K+J">K. J. Satzinger</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Y. Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Smith%2C+A">A. Smith</a>, <a href="/search/quant-ph?searchtype=author&query=Knapp%2C+C">C. Knapp</a>, <a href="/search/quant-ph?searchtype=author&query=Newman%2C+M">M. Newman</a>, <a href="/search/quant-ph?searchtype=author&query=Jones%2C+C">C. Jones</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">X. Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/quant-ph?searchtype=author&query=Gidney%2C+C">C. Gidney</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">I. Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">F. Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">K. Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">J. Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">R. Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">J. C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/quant-ph?searchtype=author&query=Basso%2C+J">J. Basso</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bilmes%2C+A">A. Bilmes</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">M. Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">B. B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">D. A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">B. Burkett</a> , et al. (73 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.01180v1-abstract-short" style="display: inline;"> The discovery of topological order has revolutionized the understanding of quantum matter in modern physics and provided the theoretical foundation for many quantum error correcting codes. Realizing topologically ordered states has proven to be extremely challenging in both condensed matter and synthetic quantum systems. Here, we prepare the ground state of the toric code Hamiltonian using an effi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.01180v1-abstract-full').style.display = 'inline'; document.getElementById('2104.01180v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.01180v1-abstract-full" style="display: none;"> The discovery of topological order has revolutionized the understanding of quantum matter in modern physics and provided the theoretical foundation for many quantum error correcting codes. Realizing topologically ordered states has proven to be extremely challenging in both condensed matter and synthetic quantum systems. Here, we prepare the ground state of the toric code Hamiltonian using an efficient quantum circuit on a superconducting quantum processor. We measure a topological entanglement entropy near the expected value of $\ln2$, and simulate anyon interferometry to extract the braiding statistics of the emergent excitations. Furthermore, we investigate key aspects of the surface code, including logical state injection and the decay of the non-local order parameter. Our results demonstrate the potential for quantum processors to provide key insights into topological quantum matter and quantum error correction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.01180v1-abstract-full').style.display = 'none'; document.getElementById('2104.01180v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages 4 figures, plus supplementary materials</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 374, 1237-1241 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.06132">arXiv:2102.06132</a> <span> [<a href="https://arxiv.org/pdf/2102.06132">pdf</a>, <a href="https://arxiv.org/format/2102.06132">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-021-03588-y">10.1038/s41586-021-03588-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exponential suppression of bit or phase flip errors with repetitive error correction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Satzinger%2C+K+J">Kevin J. Satzinger</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</a>, <a href="/search/quant-ph?searchtype=author&query=Dunsworth%2C+A">Andrew Dunsworth</a>, <a href="/search/quant-ph?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/quant-ph?searchtype=author&query=Quintana%2C+C">Chris Quintana</a>, <a href="/search/quant-ph?searchtype=author&query=McEwen%2C+M">Matt McEwen</a>, <a href="/search/quant-ph?searchtype=author&query=Barends%2C+R">Rami Barends</a>, <a href="/search/quant-ph?searchtype=author&query=Klimov%2C+P+V">Paul V. Klimov</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Jones%2C+C">Cody Jones</a>, <a href="/search/quant-ph?searchtype=author&query=Petukhov%2C+A">Andre Petukhov</a>, <a href="/search/quant-ph?searchtype=author&query=Kafri%2C+D">Dvir Kafri</a>, <a href="/search/quant-ph?searchtype=author&query=Demura%2C+S">Sean Demura</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Gidney%2C+C">Craig Gidney</a>, <a href="/search/quant-ph?searchtype=author&query=Fowler%2C+A+G">Austin G. Fowler</a>, <a href="/search/quant-ph?searchtype=author&query=Putterman%2C+H">Harald Putterman</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">Igor Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a> , et al. (66 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.06132v1-abstract-short" style="display: inline;"> Realizing the potential of quantum computing will require achieving sufficiently low logical error rates. Many applications call for error rates in the $10^{-15}$ regime, but state-of-the-art quantum platforms typically have physical error rates near $10^{-3}$. Quantum error correction (QEC) promises to bridge this divide by distributing quantum logical information across many physical qubits so t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.06132v1-abstract-full').style.display = 'inline'; document.getElementById('2102.06132v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.06132v1-abstract-full" style="display: none;"> Realizing the potential of quantum computing will require achieving sufficiently low logical error rates. Many applications call for error rates in the $10^{-15}$ regime, but state-of-the-art quantum platforms typically have physical error rates near $10^{-3}$. Quantum error correction (QEC) promises to bridge this divide by distributing quantum logical information across many physical qubits so that errors can be detected and corrected. Logical errors are then exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold. QEC also requires that the errors are local and that performance is maintained over many rounds of error correction, two major outstanding experimental challenges. Here, we implement 1D repetition codes embedded in a 2D grid of superconducting qubits which demonstrate exponential suppression of bit or phase-flip errors, reducing logical error per round by more than $100\times$ when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analyzing error correlations with high precision, and characterize the locality of errors in a device performing QEC for the first time. Finally, we perform error detection using a small 2D surface code logical qubit on the same device, and show that the results from both 1D and 2D codes agree with numerical simulations using a simple depolarizing error model. These findings demonstrate that superconducting qubits are on a viable path towards fault tolerant quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.06132v1-abstract-full').style.display = 'none'; document.getElementById('2102.06132v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature volume 595, pages 383-387 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.05767">arXiv:2102.05767</a> <span> [<a href="https://arxiv.org/pdf/2102.05767">pdf</a>, <a href="https://arxiv.org/format/2102.05767">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Error mitigation via stabilizer measurement emulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Greene%2C+A">A. Greene</a>, <a href="/search/quant-ph?searchtype=author&query=Kjaergaard%2C+M">M. Kjaergaard</a>, <a href="/search/quant-ph?searchtype=author&query=Schwartz%2C+M+E">M. E. Schwartz</a>, <a href="/search/quant-ph?searchtype=author&query=Samach%2C+G+O">G. O. Samach</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=O%27Keeffe%2C+M">M. O'Keeffe</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+D+K">D. K. Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Marvian%2C+M">M. Marvian</a>, <a href="/search/quant-ph?searchtype=author&query=Melville%2C+A">A. Melville</a>, <a href="/search/quant-ph?searchtype=author&query=Niedzielski%2C+B+M">B. M. Niedzielski</a>, <a href="/search/quant-ph?searchtype=author&query=Vepsalainen%2C+A">A. Vepsalainen</a>, <a href="/search/quant-ph?searchtype=author&query=Winik%2C+R">R. Winik</a>, <a href="/search/quant-ph?searchtype=author&query=Yoder%2C+J">J. Yoder</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+D">D. Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Lloyd%2C+S">S. Lloyd</a>, <a href="/search/quant-ph?searchtype=author&query=Orlando%2C+T+P">T. P. Orlando</a>, <a href="/search/quant-ph?searchtype=author&query=Marvian%2C+I">I. Marvian</a>, <a href="/search/quant-ph?searchtype=author&query=Gustavsson%2C+S">S. Gustavsson</a>, <a href="/search/quant-ph?searchtype=author&query=Oliver%2C+W+D">W. D. Oliver</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.05767v1-abstract-short" style="display: inline;"> Dynamical decoupling (DD) is a widely-used quantum control technique that takes advantage of temporal symmetries in order to partially suppress quantum errors without the need resource-intensive error detection and correction protocols. This and other open-loop error mitigation techniques are critical for quantum information processing in the era of Noisy Intermediate-Scale Quantum technology. How… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.05767v1-abstract-full').style.display = 'inline'; document.getElementById('2102.05767v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.05767v1-abstract-full" style="display: none;"> Dynamical decoupling (DD) is a widely-used quantum control technique that takes advantage of temporal symmetries in order to partially suppress quantum errors without the need resource-intensive error detection and correction protocols. This and other open-loop error mitigation techniques are critical for quantum information processing in the era of Noisy Intermediate-Scale Quantum technology. However, despite its utility, dynamical decoupling does not address errors which occur at unstructured times during a circuit, including certain commonly-encountered noise mechanisms such as cross-talk and imperfectly calibrated control pulses. Here, we introduce and demonstrate an alternative technique - `quantum measurement emulation' (QME) - that effectively emulates the measurement of stabilizer operators via stochastic gate application, leading to a first-order insensitivity to coherent errors. The QME protocol enables error suppression based on the stabilizer code formalism without the need for costly measurements and feedback, and it is particularly well-suited to discrete coherent errors that are challenging for DD to address. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.05767v1-abstract-full').style.display = 'none'; document.getElementById('2102.05767v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.08870">arXiv:2101.08870</a> <span> [<a href="https://arxiv.org/pdf/2101.08870">pdf</a>, <a href="https://arxiv.org/format/2101.08870">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.abg5029">10.1126/science.abg5029 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Information Scrambling in Computationally Complex Quantum Circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Roushan%2C+P">Pedram Roushan</a>, <a href="/search/quant-ph?searchtype=author&query=Quintana%2C+C">Chris Quintana</a>, <a href="/search/quant-ph?searchtype=author&query=Mandra%2C+S">Salvatore Mandra</a>, <a href="/search/quant-ph?searchtype=author&query=Marshall%2C+J">Jeffrey Marshall</a>, <a href="/search/quant-ph?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Barends%2C+R">Rami Barends</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Boixo%2C+S">Sergio Boixo</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chiaro%2C+B">Benjamin Chiaro</a>, <a href="/search/quant-ph?searchtype=author&query=Collins%2C+R">Roberto Collins</a>, <a href="/search/quant-ph?searchtype=author&query=Courtney%2C+W">William Courtney</a>, <a href="/search/quant-ph?searchtype=author&query=Demura%2C+S">Sean Demura</a> , et al. (68 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.08870v1-abstract-short" style="display: inline;"> Interaction in quantum systems can spread initially localized quantum information into the many degrees of freedom of the entire system. Understanding this process, known as quantum scrambling, is the key to resolving various conundrums in physics. Here, by measuring the time-dependent evolution and fluctuation of out-of-time-order correlators, we experimentally investigate the dynamics of quantum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.08870v1-abstract-full').style.display = 'inline'; document.getElementById('2101.08870v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.08870v1-abstract-full" style="display: none;"> Interaction in quantum systems can spread initially localized quantum information into the many degrees of freedom of the entire system. Understanding this process, known as quantum scrambling, is the key to resolving various conundrums in physics. Here, by measuring the time-dependent evolution and fluctuation of out-of-time-order correlators, we experimentally investigate the dynamics of quantum scrambling on a 53-qubit quantum processor. We engineer quantum circuits that distinguish the two mechanisms associated with quantum scrambling, operator spreading and operator entanglement, and experimentally observe their respective signatures. We show that while operator spreading is captured by an efficient classical model, operator entanglement requires exponentially scaled computational resources to simulate. These results open the path to studying complex and practically relevant physical observables with near-term quantum processors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.08870v1-abstract-full').style.display = 'none'; document.getElementById('2101.08870v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 374, 1479 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.00921">arXiv:2012.00921</a> <span> [<a href="https://arxiv.org/pdf/2012.00921">pdf</a>, <a href="https://arxiv.org/format/2012.00921">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-021-03576-2">10.1038/s41586-021-03576-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Accurately computing electronic properties of a quantum ring </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/quant-ph?searchtype=author&query=McCourt%2C+T">T. McCourt</a>, <a href="/search/quant-ph?searchtype=author&query=Mi%2C+X">X. Mi</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Z">Z. Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+M+Y">M. Y. Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Mruczkiewicz%2C+W">W. Mruczkiewicz</a>, <a href="/search/quant-ph?searchtype=author&query=Aleiner%2C+I">I. Aleiner</a>, <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">F. Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">K. Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Atalaya%2C+J">J. Atalaya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">R. Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">J. C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bourassa%2C+A">A. Bourassa</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">M. Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">B. B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">D. A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">B. Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">N. Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Campero%2C+J">J. Campero</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/quant-ph?searchtype=author&query=Collins%2C+R">R. Collins</a>, <a href="/search/quant-ph?searchtype=author&query=Courtney%2C+W">W. Courtney</a> , et al. (67 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.00921v2-abstract-short" style="display: inline;"> A promising approach to study condensed-matter systems is to simulate them on an engineered quantum platform. However, achieving the accuracy needed to outperform classical methods has been an outstanding challenge. Here, using eighteen superconducting qubits, we provide an experimental blueprint for an accurate condensed-matter simulator and demonstrate how to probe fundamental electronic propert… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00921v2-abstract-full').style.display = 'inline'; document.getElementById('2012.00921v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.00921v2-abstract-full" style="display: none;"> A promising approach to study condensed-matter systems is to simulate them on an engineered quantum platform. However, achieving the accuracy needed to outperform classical methods has been an outstanding challenge. Here, using eighteen superconducting qubits, we provide an experimental blueprint for an accurate condensed-matter simulator and demonstrate how to probe fundamental electronic properties. We benchmark the underlying method by reconstructing the single-particle band-structure of a one-dimensional wire. We demonstrate nearly complete mitigation of decoherence and readout errors and arrive at an accuracy in measuring energy eigenvalues of this wire with an error of ~0.01 rad, whereas typical energy scales are of order 1 rad. Insight into this unprecedented algorithm fidelity is gained by highlighting robust properties of a Fourier transform, including the ability to resolve eigenenergies with a statistical uncertainty of 1e-4 rad. Furthermore, we synthesize magnetic flux and disordered local potentials, two key tenets of a condensed-matter system. When sweeping the magnetic flux, we observe avoided level crossings in the spectrum, a detailed fingerprint of the spatial distribution of local disorder. Combining these methods, we reconstruct electronic properties of the eigenstates where we observe persistent currents and a strong suppression of conductance with added disorder. Our work describes an accurate method for quantum simulation and paves the way to study novel quantum materials with superconducting qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00921v2-abstract-full').style.display = 'none'; document.getElementById('2012.00921v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2011.05230">arXiv:2011.05230</a> <span> [<a href="https://arxiv.org/pdf/2011.05230">pdf</a>, <a href="https://arxiv.org/format/2011.05230">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0037093">10.1063/5.0037093 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simplified Josephson-junction fabrication process for reproducibly high-performance superconducting qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Osman%2C+A">A. Osman</a>, <a href="/search/quant-ph?searchtype=author&query=Simon%2C+J">J. Simon</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Kosen%2C+S">S. Kosen</a>, <a href="/search/quant-ph?searchtype=author&query=Krantz%2C+P">P. Krantz</a>, <a href="/search/quant-ph?searchtype=author&query=Perez%2C+D">D. Perez</a>, <a href="/search/quant-ph?searchtype=author&query=Scigliuzzo%2C+M">M. Scigliuzzo</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=Roudsari%2C+A+F">A. Fadavi Roudsari</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2011.05230v1-abstract-short" style="display: inline;"> We introduce a simplified fabrication technique for Josephson junctions and demonstrate superconducting Xmon qubits with $T_1$ relaxation times averaging above 50$~渭$s ($Q>$1.5$\times$ 10$^6$). Current shadow-evaporation techniques for aluminum-based Josephson junctions require a separate lithography step to deposit a patch that makes a galvanic, superconducting connection between the junction ele… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.05230v1-abstract-full').style.display = 'inline'; document.getElementById('2011.05230v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2011.05230v1-abstract-full" style="display: none;"> We introduce a simplified fabrication technique for Josephson junctions and demonstrate superconducting Xmon qubits with $T_1$ relaxation times averaging above 50$~渭$s ($Q>$1.5$\times$ 10$^6$). Current shadow-evaporation techniques for aluminum-based Josephson junctions require a separate lithography step to deposit a patch that makes a galvanic, superconducting connection between the junction electrodes and the circuit wiring layer. The patch connection eliminates parasitic junctions, which otherwise contribute significantly to dielectric loss. In our patch-integrated cross-type (PICT) junction technique, we use one lithography step and one vacuum cycle to evaporate both the junction electrodes and the patch. In a study of more than 3600 junctions, we show an average resistance variation of 3.7$\%$ on a wafer that contains forty 0.5$\times$0.5-cm$^2$ chips, with junction areas ranging between 0.01 and 0.16 $渭$m$^2$. The average on-chip spread in resistance is 2.7$\%$, with 20 chips varying between 1.4 and 2$\%$. For the junction sizes used for transmon qubits, we deduce a wafer-level transition-frequency variation of 1.7-2.5$\%$. We show that 60-70$\%$ of this variation is attributed to junction-area fluctuations, while the rest is caused by tunnel-junction inhomogeneity. Such high frequency predictability is a requirement for scaling-up the number of qubits in a quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.05230v1-abstract-full').style.display = 'none'; document.getElementById('2011.05230v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.07965">arXiv:2010.07965</a> <span> [<a href="https://arxiv.org/pdf/2010.07965">pdf</a>, <a href="https://arxiv.org/format/2010.07965">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of separated dynamics of charge and spin in the Fermi-Hubbard model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/quant-ph?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/quant-ph?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/quant-ph?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/quant-ph?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/quant-ph?searchtype=author&query=Barends%2C+R">Rami Barends</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Boixo%2C+S">Sergio Boixo</a>, <a href="/search/quant-ph?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/quant-ph?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/quant-ph?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/quant-ph?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/quant-ph?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu-An Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chiaro%2C+B">Ben Chiaro</a>, <a href="/search/quant-ph?searchtype=author&query=Collins%2C+R">Roberto Collins</a>, <a href="/search/quant-ph?searchtype=author&query=Cotton%2C+S+J">Stephen J. Cotton</a>, <a href="/search/quant-ph?searchtype=author&query=Courtney%2C+W">William Courtney</a>, <a href="/search/quant-ph?searchtype=author&query=Demura%2C+S">Sean Demura</a>, <a href="/search/quant-ph?searchtype=author&query=Derk%2C+A">Alan Derk</a>, <a href="/search/quant-ph?searchtype=author&query=Dunsworth%2C+A">Andrew Dunsworth</a>, <a href="/search/quant-ph?searchtype=author&query=Eppens%2C+D">Daniel Eppens</a>, <a href="/search/quant-ph?searchtype=author&query=Eckl%2C+T">Thomas Eckl</a> , et al. (74 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2010.07965v1-abstract-short" style="display: inline;"> Strongly correlated quantum systems give rise to many exotic physical phenomena, including high-temperature superconductivity. Simulating these systems on quantum computers may avoid the prohibitively high computational cost incurred in classical approaches. However, systematic errors and decoherence effects presented in current quantum devices make it difficult to achieve this. Here, we simulate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.07965v1-abstract-full').style.display = 'inline'; document.getElementById('2010.07965v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.07965v1-abstract-full" style="display: none;"> Strongly correlated quantum systems give rise to many exotic physical phenomena, including high-temperature superconductivity. Simulating these systems on quantum computers may avoid the prohibitively high computational cost incurred in classical approaches. However, systematic errors and decoherence effects presented in current quantum devices make it difficult to achieve this. Here, we simulate the dynamics of the one-dimensional Fermi-Hubbard model using 16 qubits on a digital superconducting quantum processor. We observe separations in the spreading velocities of charge and spin densities in the highly excited regime, a regime that is beyond the conventional quasiparticle picture. To minimize systematic errors, we introduce an accurate gate calibration procedure that is fast enough to capture temporal drifts of the gate parameters. We also employ a sequence of error-mitigation techniques to reduce decoherence effects and residual systematic errors. These procedures allow us to simulate the time evolution of the model faithfully despite having over 600 two-qubit gates in our circuits. Our experiment charts a path to practical quantum simulation of strongly correlated phenomena using available quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.07965v1-abstract-full').style.display = 'none'; document.getElementById('2010.07965v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 15 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.13522">arXiv:2003.13522</a> <span> [<a href="https://arxiv.org/pdf/2003.13522">pdf</a>, <a href="https://arxiv.org/format/2003.13522">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevX.10.041054">10.1103/PhysRevX.10.041054 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Primary thermometry of propagating microwaves in the quantum regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Scigliuzzo%2C+M">Marco Scigliuzzo</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Besse%2C+J">Jean-Claude Besse</a>, <a href="/search/quant-ph?searchtype=author&query=Wallraff%2C+A">Andreas Wallraff</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Gasparinetti%2C+S">Simone Gasparinetti</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2003.13522v1-abstract-short" style="display: inline;"> The ability to control and measure the temperature of propagating microwave modes down to very low temperatures is indispensable for quantum information processing, and may open opportunities for studies of heat transport at the nanoscale, also in the quantum regime. Here we propose and experimentally demonstrate primary thermometry of propagating microwaves using a transmon-type superconducting c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.13522v1-abstract-full').style.display = 'inline'; document.getElementById('2003.13522v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.13522v1-abstract-full" style="display: none;"> The ability to control and measure the temperature of propagating microwave modes down to very low temperatures is indispensable for quantum information processing, and may open opportunities for studies of heat transport at the nanoscale, also in the quantum regime. Here we propose and experimentally demonstrate primary thermometry of propagating microwaves using a transmon-type superconducting circuit. Our device operates continuously, with a sensitivity down to $4\times 10^{-4}$ photons/$\sqrt{\mbox{Hz}}$ and a bandwidth of 40 MHz. We measure the thermal occupation of the modes of a highly attenuated coaxial cable in a range of 0.001 to 0.4 thermal photons, corresponding to a temperature range from 35 mK to 210 mK at a frequency around 5 GHz. To increase the radiation temperature in a controlled fashion, we either inject calibrated, wideband digital noise, or heat the device and its environment. This thermometry scheme can find applications in benchmarking and characterization of cryogenic microwave setups, temperature measurements in hybrid quantum systems, and quantum thermodynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.13522v1-abstract-full').style.display = 'none'; document.getElementById('2003.13522v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. X 10, 041054 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.02782">arXiv:2003.02782</a> <span> [<a href="https://arxiv.org/pdf/2003.02782">pdf</a>, <a href="https://arxiv.org/format/2003.02782">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-021-21098-3">10.1038/s41467-021-21098-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multi-level Quantum Noise Spectroscopy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sung%2C+Y">Youngkyu Sung</a>, <a href="/search/quant-ph?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">Antti Veps盲l盲inen</a>, <a href="/search/quant-ph?searchtype=author&query=Braum%C3%BCller%2C+J">Jochen Braum眉ller</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+F">Fei Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J+I">Joel I-Jan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Kjaergaard%2C+M">Morten Kjaergaard</a>, <a href="/search/quant-ph?searchtype=author&query=Winik%2C+R">Roni Winik</a>, <a href="/search/quant-ph?searchtype=author&query=Krantz%2C+P">Philip Krantz</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Melville%2C+A+J">Alexander J. Melville</a>, <a href="/search/quant-ph?searchtype=author&query=Niedzielski%2C+B+M">Bethany M. Niedzielski</a>, <a href="/search/quant-ph?searchtype=author&query=Schwartz%2C+M+E">Mollie E. Schwartz</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+D+K">David K. Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Yoder%2C+J+L">Jonilyn L. Yoder</a>, <a href="/search/quant-ph?searchtype=author&query=Orlando%2C+T+P">Terry P. Orlando</a>, <a href="/search/quant-ph?searchtype=author&query=Gustavsson%2C+S">Simon Gustavsson</a>, <a href="/search/quant-ph?searchtype=author&query=Oliver%2C+W+D">William D. Oliver</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2003.02782v2-abstract-short" style="display: inline;"> System noise identification is crucial to the engineering of robust quantum systems. Although existing quantum noise spectroscopy (QNS) protocols measure an aggregate amount of noise affecting a quantum system, they generally cannot distinguish between the underlying processes that contribute to it. Here, we propose and experimentally validate a spin-locking-based QNS protocol that exploits the mu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.02782v2-abstract-full').style.display = 'inline'; document.getElementById('2003.02782v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.02782v2-abstract-full" style="display: none;"> System noise identification is crucial to the engineering of robust quantum systems. Although existing quantum noise spectroscopy (QNS) protocols measure an aggregate amount of noise affecting a quantum system, they generally cannot distinguish between the underlying processes that contribute to it. Here, we propose and experimentally validate a spin-locking-based QNS protocol that exploits the multi-level energy structure of a superconducting qubit to achieve two notable advances. First, our protocol extends the spectral range of weakly anharmonic qubit spectrometers beyond the present limitations set by their lack of strong anharmonicity. Second, the additional information gained from probing the higher-excited levels enables us to identify and distinguish contributions from different underlying noise mechanisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.02782v2-abstract-full').style.display = 'none'; document.getElementById('2003.02782v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 12, 967 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.08838">arXiv:2001.08838</a> <span> [<a href="https://arxiv.org/pdf/2001.08838">pdf</a>, <a href="https://arxiv.org/format/2001.08838">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Programming a quantum computer with quantum instructions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kjaergaard%2C+M">Morten Kjaergaard</a>, <a href="/search/quant-ph?searchtype=author&query=Schwartz%2C+M+E">Mollie E. Schwartz</a>, <a href="/search/quant-ph?searchtype=author&query=Greene%2C+A">Ami Greene</a>, <a href="/search/quant-ph?searchtype=author&query=Samach%2C+G+O">Gabriel O. Samach</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=O%27Keeffe%2C+M">Michael O'Keeffe</a>, <a href="/search/quant-ph?searchtype=author&query=McNally%2C+C+M">Christopher M. McNally</a>, <a href="/search/quant-ph?searchtype=author&query=Braum%C3%BCller%2C+J">Jochen Braum眉ller</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+D+K">David K. Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Krantz%2C+P">Philip Krantz</a>, <a href="/search/quant-ph?searchtype=author&query=Marvian%2C+M">Milad Marvian</a>, <a href="/search/quant-ph?searchtype=author&query=Melville%2C+A">Alexander Melville</a>, <a href="/search/quant-ph?searchtype=author&query=Niedzielski%2C+B+M">Bethany M. Niedzielski</a>, <a href="/search/quant-ph?searchtype=author&query=Sung%2C+Y">Youngkyu Sung</a>, <a href="/search/quant-ph?searchtype=author&query=Winik%2C+R">Roni Winik</a>, <a href="/search/quant-ph?searchtype=author&query=Yoder%2C+J">Jonilyn Yoder</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenberg%2C+D">Danna Rosenberg</a>, <a href="/search/quant-ph?searchtype=author&query=Obenland%2C+K">Kevin Obenland</a>, <a href="/search/quant-ph?searchtype=author&query=Lloyd%2C+S">Seth Lloyd</a>, <a href="/search/quant-ph?searchtype=author&query=Orlando%2C+T+P">Terry P. Orlando</a>, <a href="/search/quant-ph?searchtype=author&query=Marvian%2C+I">Iman Marvian</a>, <a href="/search/quant-ph?searchtype=author&query=Gustavsson%2C+S">Simon Gustavsson</a>, <a href="/search/quant-ph?searchtype=author&query=Oliver%2C+W+D">William D. Oliver</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.08838v3-abstract-short" style="display: inline;"> The equivalence between the instructions used to define programs and the input data on which the instructions operate is a basic principle of classical computer architectures and programming. Replacing classical data with quantum states enables fundamentally new computational capabilities with scaling advantages for many applications, and numerous models have been proposed for realizing quantum co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.08838v3-abstract-full').style.display = 'inline'; document.getElementById('2001.08838v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.08838v3-abstract-full" style="display: none;"> The equivalence between the instructions used to define programs and the input data on which the instructions operate is a basic principle of classical computer architectures and programming. Replacing classical data with quantum states enables fundamentally new computational capabilities with scaling advantages for many applications, and numerous models have been proposed for realizing quantum computation. However, within each of these models, the quantum data are transformed by a set of gates that are compiled using solely classical information. Conventional quantum computing models thus break the instruction-data symmetry: classical instructions and quantum data are not directly interchangeable. In this work, we use a density matrix exponentiation protocol to execute quantum instructions on quantum data. In this approach, a fixed sequence of classically-defined gates performs an operation that uniquely depends on an auxiliary quantum instruction state. Our demonstration relies on a 99.7% fidelity controlled-phase gate implemented using two tunable superconducting transmon qubits, which enables an algorithmic fidelity surpassing 90% at circuit depths exceeding 70. The utilization of quantum instructions obviates the need for costly tomographic state reconstruction and recompilation, thereby enabling exponential speedup for a broad range of algorithms, including quantum principal component analysis, the measurement of entanglement spectra, and universal quantum emulation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.08838v3-abstract-full').style.display = 'none'; document.getElementById('2001.08838v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.10495">arXiv:1912.10495</a> <span> [<a href="https://arxiv.org/pdf/1912.10495">pdf</a>, <a href="https://arxiv.org/format/1912.10495">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.14.034010">10.1103/PhysRevApplied.14.034010 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Improved success probability with greater circuit depth for the quantum approximate optimization algorithm </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Vikst%C3%A5l%2C+P">Pontus Vikst氓l</a>, <a href="/search/quant-ph?searchtype=author&query=Warren%2C+C">Christopher Warren</a>, <a href="/search/quant-ph?searchtype=author&query=Svensson%2C+M">Marika Svensson</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+X">Xiu Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a>, <a href="/search/quant-ph?searchtype=author&query=Krantz%2C+P">Philip Krantz</a>, <a href="/search/quant-ph?searchtype=author&query=Kri%C5%BEan%2C+C">Christian Kri啪an</a>, <a href="/search/quant-ph?searchtype=author&query=Shiri%2C+D">Daryoush Shiri</a>, <a href="/search/quant-ph?searchtype=author&query=Svensson%2C+I">Ida-Maria Svensson</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">Giovanna Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Johansson%2C+G">G枚ran Johansson</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Ferrini%2C+G">Giulia Ferrini</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.10495v2-abstract-short" style="display: inline;"> Present-day, noisy, small or intermediate-scale quantum processors---although far from fault-tolerant---support the execution of heuristic quantum algorithms, which might enable a quantum advantage, for example, when applied to combinatorial optimization problems. On small-scale quantum processors, validations of such algorithms serve as important technology demonstrators. We implement the quantum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.10495v2-abstract-full').style.display = 'inline'; document.getElementById('1912.10495v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.10495v2-abstract-full" style="display: none;"> Present-day, noisy, small or intermediate-scale quantum processors---although far from fault-tolerant---support the execution of heuristic quantum algorithms, which might enable a quantum advantage, for example, when applied to combinatorial optimization problems. On small-scale quantum processors, validations of such algorithms serve as important technology demonstrators. We implement the quantum approximate optimization algorithm (QAOA) on our hardware platform, consisting of two superconducting transmon qubits and one parametrically modulated coupler. We solve small instances of the NP-complete exact-cover problem, with 96.6% success probability, by iterating the algorithm up to level two. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.10495v2-abstract-full').style.display = 'none'; document.getElementById('1912.10495v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 14, 034010 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.09119">arXiv:1912.09119</a> <span> [<a href="https://arxiv.org/pdf/1912.09119">pdf</a>, <a href="https://arxiv.org/format/1912.09119">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1367-2630/ab8044">10.1088/1367-2630/ab8044 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phononic loss in superconducting resonators on piezoelectric substrates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Scigliuzzo%2C+M">Marco Scigliuzzo</a>, <a href="/search/quant-ph?searchtype=author&query=Bruhat%2C+L+E">Laure E. Bruhat</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Burnett%2C+J+J">Jonathan J. Burnett</a>, <a href="/search/quant-ph?searchtype=author&query=Roudsari%2C+A+F">Anita Fadavi Roudsari</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.09119v1-abstract-short" style="display: inline;"> We numerically and experimentally investigate the phononic loss for superconducting resonators fabricated on a piezoelectric substrate. With the help of finite element method simulations, we calculate the energy loss due to electromechanical conversion into bulk and surface acoustic waves. This sets an upper limit for the resonator internal quality factor $Q_i$. To validate the simulation, we fabr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.09119v1-abstract-full').style.display = 'inline'; document.getElementById('1912.09119v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.09119v1-abstract-full" style="display: none;"> We numerically and experimentally investigate the phononic loss for superconducting resonators fabricated on a piezoelectric substrate. With the help of finite element method simulations, we calculate the energy loss due to electromechanical conversion into bulk and surface acoustic waves. This sets an upper limit for the resonator internal quality factor $Q_i$. To validate the simulation, we fabricate quarter wavelength coplanar waveguide resonators on GaAs and measure $Q_i$ as function of frequency, power and temperature. We observe a linear increase of $Q_i$ with frequency, as predicted by the simulations for a constant electromechanical coupling. Additionally, $Q_i$ shows a weak power dependence and a negligible temperature dependence around 10$\,$mK, excluding two level systems and non-equilibrium quasiparticles as the main source of losses at that temperature. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.09119v1-abstract-full').style.display = 'none'; document.getElementById('1912.09119v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.02124">arXiv:1912.02124</a> <span> [<a href="https://arxiv.org/pdf/1912.02124">pdf</a>, <a href="https://arxiv.org/format/1912.02124">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-021-00367-5">10.1038/s41534-021-00367-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterizing decoherence rates of a superconducting qubit by direct microwave scattering </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yong Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Burnett%2C+J+J">Jonathan J. Burnett</a>, <a href="/search/quant-ph?searchtype=author&query=Wiegand%2C+E">Emely Wiegand</a>, <a href="/search/quant-ph?searchtype=author&query=Suri%2C+B">Baladitya Suri</a>, <a href="/search/quant-ph?searchtype=author&query=Krantz%2C+P">Philip Krantz</a>, <a href="/search/quant-ph?searchtype=author&query=Roudsari%2C+A+F">Anita Fadavi Roudsari</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a>, <a href="/search/quant-ph?searchtype=author&query=Gasparinetti%2C+S">Simone Gasparinetti</a>, <a href="/search/quant-ph?searchtype=author&query=Johansson%2C+G">G枚ran Johansson</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.02124v1-abstract-short" style="display: inline;"> We experimentally investigate a superconducting qubit coupled to the end of an open transmission line, in a regime where the qubit decay rates to the transmission line and to its own environment are comparable. We perform measurements of coherent and incoherent scattering, on- and off-resonant fluorescence, and time-resolved dynamics to determine the decay and decoherence rates of the qubit. In pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02124v1-abstract-full').style.display = 'inline'; document.getElementById('1912.02124v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.02124v1-abstract-full" style="display: none;"> We experimentally investigate a superconducting qubit coupled to the end of an open transmission line, in a regime where the qubit decay rates to the transmission line and to its own environment are comparable. We perform measurements of coherent and incoherent scattering, on- and off-resonant fluorescence, and time-resolved dynamics to determine the decay and decoherence rates of the qubit. In particular, these measurements let us discriminate between non-radiative decay and pure dephasing. We combine and contrast results across all methods and find consistent values for the extracted rates. The results show that the pure dephasing rate is one order of magnitude smaller than the non-radiative decay rate for our qubit. Our results indicate a pathway to benchmark decoherence rates of superconducting qubits in a resonator-free setting. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.02124v1-abstract-full').style.display = 'none'; document.getElementById('1912.02124v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 7, 35 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.04417">arXiv:1901.04417</a> <span> [<a href="https://arxiv.org/pdf/1901.04417">pdf</a>, <a href="https://arxiv.org/format/1901.04417">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-019-0168-5">10.1038/s41534-019-0168-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Decoherence benchmarking of superconducting qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Burnett%2C+J">Jonathan Burnett</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Scigliuzzo%2C+M">Marco Scigliuzzo</a>, <a href="/search/quant-ph?searchtype=author&query=Niepce%2C+D">David Niepce</a>, <a href="/search/quant-ph?searchtype=author&query=Kudra%2C+M">Marina Kudra</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1901.04417v2-abstract-short" style="display: inline;"> We benchmark the decoherence of superconducting qubits to examine the temporal stability of energy-relaxation and dephasing. By collecting statistics during measurements spanning multiple days, we find the mean parameters $\overline{T_{1}}$ = 49 $渭$s and $\overline{T_{2}^{*}}$ = 95 $渭$s, however, both of these quantities fluctuate explaining the need for frequent re-calibration in qubit setups. Ou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.04417v2-abstract-full').style.display = 'inline'; document.getElementById('1901.04417v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.04417v2-abstract-full" style="display: none;"> We benchmark the decoherence of superconducting qubits to examine the temporal stability of energy-relaxation and dephasing. By collecting statistics during measurements spanning multiple days, we find the mean parameters $\overline{T_{1}}$ = 49 $渭$s and $\overline{T_{2}^{*}}$ = 95 $渭$s, however, both of these quantities fluctuate explaining the need for frequent re-calibration in qubit setups. Our main finding is that fluctuations in qubit relaxation are local to the qubit and are caused by instabilities of near-resonant two-level-systems (TLS). Through statistical analysis, we determine switching rates of these TLS and observe the coherent coupling between an individual TLS and a transmon qubit. Finally, we find evidence that the qubit's frequency stability is limited by capacitance noise. Importantly, this produces a 0.8 ms limit on the pure dephasing which we also observe. Collectively, these findings raise the need for performing qubit metrology to examine the reproducibility of qubit parameters, where these fluctuations could affect qubit gate fidelity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.04417v2-abstract-full').style.display = 'none'; document.getElementById('1901.04417v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 January, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages ArXiv version rev2</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Informationvolume 5, Article number: 9 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.09259">arXiv:1802.09259</a> <span> [<a href="https://arxiv.org/pdf/1802.09259">pdf</a>, <a href="https://arxiv.org/format/1802.09259">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/1.5026974">10.1063/1.5026974 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Period multiplication in a parametrically driven superconducting resonator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Svensson%2C+I">Ida-Maria Svensson</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=Shumeiko%2C+V">Vitaly Shumeiko</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.09259v1-abstract-short" style="display: inline;"> We report on the experimental observation of period multiplication in parametrically driven tunable superconducting resonators. We modulate the magnetic flux through a superconducting quantum interference device, attached to a quarter-wavelength resonator, with frequencies $n蠅$ close to multiples, $n=2,\,3,\,4,\,5$, of the resonator fundamental mode and observe intense output radiation at $蠅$. The… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.09259v1-abstract-full').style.display = 'inline'; document.getElementById('1802.09259v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.09259v1-abstract-full" style="display: none;"> We report on the experimental observation of period multiplication in parametrically driven tunable superconducting resonators. We modulate the magnetic flux through a superconducting quantum interference device, attached to a quarter-wavelength resonator, with frequencies $n蠅$ close to multiples, $n=2,\,3,\,4,\,5$, of the resonator fundamental mode and observe intense output radiation at $蠅$. The output field manifests $n$-fold degeneracy with respect to the phase, the $n$ states are phase shifted by $2蟺/n$ with respect to each other. Our demonstration verifies the theoretical prediction by Guo et al. in PRL 111, 205303 (2013), and paves the way for engineering complex macroscopic quantum cat states with microwave photons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.09259v1-abstract-full').style.display = 'none'; document.getElementById('1802.09259v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 113, 022602 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.05529">arXiv:1802.05529</a> <span> [<a href="https://arxiv.org/pdf/1802.05529">pdf</a>, <a href="https://arxiv.org/format/1802.05529">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.124.140503">10.1103/PhysRevLett.124.140503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of broadband entanglement in microwave radiation from a single time-varying boundary condition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Schneider%2C+B+H">B. H. Schneider</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">A. Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Svensson%2C+I+M">I. M. Svensson</a>, <a href="/search/quant-ph?searchtype=author&query=Aref%2C+T">T. Aref</a>, <a href="/search/quant-ph?searchtype=author&query=Johansson%2C+G">G. Johansson</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">P. Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.05529v3-abstract-short" style="display: inline;"> Entangled pairs of microwave photons are commonly produced in the narrow frequency band of a resonator, which represents a modified vacuum density of states. We use a broadband, semi-infinite transmission line terminated by a superconducting quantum interference device (SQUID). A weak pump signal modulates the SQUID inductance, resulting in a single time-varying boundary condition. We detect both… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.05529v3-abstract-full').style.display = 'inline'; document.getElementById('1802.05529v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.05529v3-abstract-full" style="display: none;"> Entangled pairs of microwave photons are commonly produced in the narrow frequency band of a resonator, which represents a modified vacuum density of states. We use a broadband, semi-infinite transmission line terminated by a superconducting quantum interference device (SQUID). A weak pump signal modulates the SQUID inductance, resulting in a single time-varying boundary condition. We detect both quadratures of the microwave radiation emitted at two different frequencies separated by 0.7~GHz. We determine the type and purity of entanglement from the noise correlations and an in-situ noise and power calibration. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.05529v3-abstract-full').style.display = 'none'; document.getElementById('1802.05529v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 124, 140503 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1801.10204">arXiv:1801.10204</a> <span> [<a href="https://arxiv.org/pdf/1801.10204">pdf</a>, <a href="https://arxiv.org/format/1801.10204">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1742-6596/969/1/012131">10.1088/1742-6596/969/1/012131 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Noise and loss of superconducting aluminium resonators at single photon energies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Burnett%2C+J">Jonathan Burnett</a>, <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Niepce%2C+D">David Niepce</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1801.10204v1-abstract-short" style="display: inline;"> The loss and noise mechanisms of superconducting resonators are useful tools for understanding decoherence in superconducting circuits. While the loss mechanisms have been heavily studied, noise in superconducting resonators has only recently been investigated. In particular, there is an absence of literature on noise in the single photon limit. Here, we measure the loss and noise of an aluminium… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.10204v1-abstract-full').style.display = 'inline'; document.getElementById('1801.10204v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1801.10204v1-abstract-full" style="display: none;"> The loss and noise mechanisms of superconducting resonators are useful tools for understanding decoherence in superconducting circuits. While the loss mechanisms have been heavily studied, noise in superconducting resonators has only recently been investigated. In particular, there is an absence of literature on noise in the single photon limit. Here, we measure the loss and noise of an aluminium on silicon quarter-wavelength ($位/4$) resonator in the single photon regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.10204v1-abstract-full').style.display = 'none'; document.getElementById('1801.10204v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 January, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">LT28 Conference proceeding, to be published in IOP Conference Series</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1801.04566">arXiv:1801.04566</a> <span> [<a href="https://arxiv.org/pdf/1801.04566">pdf</a>, <a href="https://arxiv.org/format/1801.04566">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.97.144502">10.1103/PhysRevB.97.144502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nondegenerate parametric oscillations in a tunable superconducting resonator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/quant-ph?searchtype=author&query=Krantz%2C+P">Philip Krantz</a>, <a href="/search/quant-ph?searchtype=author&query=Simoen%2C+M">Micha毛l Simoen</a>, <a href="/search/quant-ph?searchtype=author&query=Svensson%2C+I">Ida-Maria Svensson</a>, <a href="/search/quant-ph?searchtype=author&query=Schneider%2C+B">Ben Schneider</a>, <a href="/search/quant-ph?searchtype=author&query=Shumeiko%2C+V">Vitaly Shumeiko</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1801.04566v1-abstract-short" style="display: inline;"> We investigate nondegenerate parametric oscillations in a multimode superconducting microwave resonator that is terminated by a SQUID. The parametric effect is achieved by modulating magnetic flux through the SQUID at a frequency close to the sum of two resonator-mode frequencies. For modulation amplitudes exceeding an instability threshold, self-sustained oscillations are observed in both modes.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.04566v1-abstract-full').style.display = 'inline'; document.getElementById('1801.04566v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1801.04566v1-abstract-full" style="display: none;"> We investigate nondegenerate parametric oscillations in a multimode superconducting microwave resonator that is terminated by a SQUID. The parametric effect is achieved by modulating magnetic flux through the SQUID at a frequency close to the sum of two resonator-mode frequencies. For modulation amplitudes exceeding an instability threshold, self-sustained oscillations are observed in both modes. The amplitudes of these oscillations show good quantitative agreement with a theoretical model. The oscillation phases are found to be correlated and exhibit strong fluctuations which broaden the oscillation spectral linewidths. These linewidths are significantly reduced by applying a weak on-resonance tone, which also suppresses the phase fluctuations. When the weak tone is detuned, we observe synchronization of the oscillation frequency with the frequency of the input. For the detuned input, we also observe an emergence of three idlers in the output. This observation is in agreement with theory indicating four-mode amplification and squeezing of a coherent input. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.04566v1-abstract-full').style.display = 'none'; document.getElementById('1801.04566v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 January, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 97, 144502 (2018) </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Bengtsson%2C+A&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Bengtsson%2C+A&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Bengtsson%2C+A&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div 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