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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <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/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/cond-mat?searchtype=author&query=Gyawali%2C+G">Gaurav Gyawali</a>, <a href="/search/cond-mat?searchtype=author&query=Cochran%2C+T">Tyler Cochran</a>, <a href="/search/cond-mat?searchtype=author&query=Lensky%2C+Y">Yuri Lensky</a>, <a href="/search/cond-mat?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/cond-mat?searchtype=author&query=Karamlou%2C+A+H">Amir H. Karamlou</a>, <a href="/search/cond-mat?searchtype=author&query=Kechedzhi%2C+K">Kostyantyn Kechedzhi</a>, <a href="/search/cond-mat?searchtype=author&query=Berndtsson%2C+J">Julia Berndtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Westerhout%2C+T">Tom Westerhout</a>, <a href="/search/cond-mat?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/cond-mat?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/cond-mat?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/cond-mat?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a>, <a href="/search/cond-mat?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/cond-mat?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/cond-mat?searchtype=author&query=Astrakhantsev%2C+N">Nikita Astrakhantsev</a>, <a href="/search/cond-mat?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/cond-mat?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/cond-mat?searchtype=author&query=Ballard%2C+B">Brian Ballard</a>, <a href="/search/cond-mat?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/cond-mat?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/cond-mat?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/cond-mat?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/cond-mat?searchtype=author&query=Cochran%2C+T+A">Tyler A. Cochran</a>, <a href="/search/cond-mat?searchtype=author&query=Jobst%2C+B">Bernhard Jobst</a>, <a href="/search/cond-mat?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/cond-mat?searchtype=author&query=Lensky%2C+Y+D">Yuri D. Lensky</a>, <a href="/search/cond-mat?searchtype=author&query=Gyawali%2C+G">Gaurav Gyawali</a>, <a href="/search/cond-mat?searchtype=author&query=Eassa%2C+N">Norhan Eassa</a>, <a href="/search/cond-mat?searchtype=author&query=Will%2C+M">Melissa Will</a>, <a href="/search/cond-mat?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/cond-mat?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/cond-mat?searchtype=author&query=Beni%2C+L+A">Laleh Aghababaie Beni</a>, <a href="/search/cond-mat?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/cond-mat?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/cond-mat?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/cond-mat?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/cond-mat?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/cond-mat?searchtype=author&query=Ballard%2C+B">Brian Ballard</a>, <a href="/search/cond-mat?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/cond-mat?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/cond-mat?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/cond-mat?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/cond-mat?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/cond-mat?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/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/cond-mat?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/cond-mat?searchtype=author&query=Astrakhantsev%2C+N">Nikita Astrakhantsev</a>, <a href="/search/cond-mat?searchtype=author&query=Karamlou%2C+A+H">Amir H. Karamlou</a>, <a href="/search/cond-mat?searchtype=author&query=Berndtsson%2C+J">Julia Berndtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Motruk%2C+J">Johannes Motruk</a>, <a href="/search/cond-mat?searchtype=author&query=Szasz%2C+A">Aaron Szasz</a>, <a href="/search/cond-mat?searchtype=author&query=Gross%2C+J+A">Jonathan A. Gross</a>, <a href="/search/cond-mat?searchtype=author&query=Schuckert%2C+A">Alexander Schuckert</a>, <a href="/search/cond-mat?searchtype=author&query=Westerhout%2C+T">Tom Westerhout</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Y">Yaxing Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Forati%2C+E">Ebrahim Forati</a>, <a href="/search/cond-mat?searchtype=author&query=Rossi%2C+D">Dario Rossi</a>, <a href="/search/cond-mat?searchtype=author&query=Kobrin%2C+B">Bryce Kobrin</a>, <a href="/search/cond-mat?searchtype=author&query=Di+Paolo%2C+A">Agustin Di Paolo</a>, <a href="/search/cond-mat?searchtype=author&query=Klots%2C+A+R">Andrey R. Klots</a>, <a href="/search/cond-mat?searchtype=author&query=Drozdov%2C+I">Ilya Drozdov</a>, <a href="/search/cond-mat?searchtype=author&query=Kurilovich%2C+V+D">Vladislav D. Kurilovich</a>, <a href="/search/cond-mat?searchtype=author&query=Petukhov%2C+A">Andre Petukhov</a>, <a href="/search/cond-mat?searchtype=author&query=Ioffe%2C+L+B">Lev B. Ioffe</a>, <a href="/search/cond-mat?searchtype=author&query=Elben%2C+A">Andreas Elben</a>, <a href="/search/cond-mat?searchtype=author&query=Rath%2C+A">Aniket Rath</a>, <a href="/search/cond-mat?searchtype=author&query=Vitale%2C+V">Vittorio Vitale</a>, <a href="/search/cond-mat?searchtype=author&query=Vermersch%2C+B">Benoit Vermersch</a>, <a href="/search/cond-mat?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/cond-mat?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/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/cond-mat?searchtype=author&query=Hoke%2C+J+C">Jesse C. Hoke</a>, <a href="/search/cond-mat?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</a>, <a href="/search/cond-mat?searchtype=author&query=Rosenberg%2C+E">Eliott Rosenberg</a>, <a href="/search/cond-mat?searchtype=author&query=Abanin%2C+D">Dmitry Abanin</a>, <a href="/search/cond-mat?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/cond-mat?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/cond-mat?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/cond-mat?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/cond-mat?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/cond-mat?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/cond-mat?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/cond-mat?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/cond-mat?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/cond-mat?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/cond-mat?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/cond-mat?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/cond-mat?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/cond-mat?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/cond-mat?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/cond-mat?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/cond-mat?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/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/cond-mat?searchtype=author&query=Andersen%2C+T+I">Trond I. Andersen</a>, <a href="/search/cond-mat?searchtype=author&query=Lensky%2C+Y+D">Yuri D. Lensky</a>, <a href="/search/cond-mat?searchtype=author&query=Kechedzhi%2C+K">Kostyantyn Kechedzhi</a>, <a href="/search/cond-mat?searchtype=author&query=Drozdov%2C+I">Ilya Drozdov</a>, <a href="/search/cond-mat?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Hong%2C+S">Sabrina Hong</a>, <a href="/search/cond-mat?searchtype=author&query=Morvan%2C+A">Alexis Morvan</a>, <a href="/search/cond-mat?searchtype=author&query=Mi%2C+X">Xiao Mi</a>, <a href="/search/cond-mat?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/cond-mat?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/cond-mat?searchtype=author&query=Allen%2C+R">Richard Allen</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/cond-mat?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/cond-mat?searchtype=author&query=Asfaw%2C+A">Abraham Asfaw</a>, <a href="/search/cond-mat?searchtype=author&query=Atalaya%2C+J">Juan Atalaya</a>, <a href="/search/cond-mat?searchtype=author&query=Babbush%2C+R">Ryan Babbush</a>, <a href="/search/cond-mat?searchtype=author&query=Bacon%2C+D">Dave Bacon</a>, <a href="/search/cond-mat?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/cond-mat?searchtype=author&query=Bortoli%2C+G">Gina Bortoli</a>, <a href="/search/cond-mat?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/cond-mat?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/cond-mat?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/cond-mat?searchtype=author&query=Broughton%2C+M">Michael Broughton</a>, <a href="/search/cond-mat?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/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Opremcak%2C+A">Alex Opremcak</a>, <a href="/search/cond-mat?searchtype=author&query=Sterling%2C+G">George Sterling</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A">Alexander Korotkov</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Acharya%2C+R">Rajeev Acharya</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Arute%2C+F">Frank Arute</a>, <a href="/search/cond-mat?searchtype=author&query=Arya%2C+K">Kunal Arya</a>, <a href="/search/cond-mat?searchtype=author&query=Bardin%2C+J+C">Joseph C. Bardin</a>, <a href="/search/cond-mat?searchtype=author&query=Bengtsson%2C+A">Andreas Bengtsson</a>, <a href="/search/cond-mat?searchtype=author&query=Bourassa%2C+A">Alexandre Bourassa</a>, <a href="/search/cond-mat?searchtype=author&query=Bovaird%2C+J">Jenna Bovaird</a>, <a href="/search/cond-mat?searchtype=author&query=Brill%2C+L">Leon Brill</a>, <a href="/search/cond-mat?searchtype=author&query=Buckley%2C+B+B">Bob B. Buckley</a>, <a href="/search/cond-mat?searchtype=author&query=Buell%2C+D+A">David A. Buell</a>, <a href="/search/cond-mat?searchtype=author&query=Burger%2C+T">Tim Burger</a>, <a href="/search/cond-mat?searchtype=author&query=Burkett%2C+B">Brian Burkett</a>, <a href="/search/cond-mat?searchtype=author&query=Bushnell%2C+N">Nicholas Bushnell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">Ben Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Cogan%2C+J">Josh Cogan</a>, <a href="/search/cond-mat?searchtype=author&query=Collins%2C+R">Roberto Collins</a>, <a href="/search/cond-mat?searchtype=author&query=Crook%2C+A+L">Alexander L. Crook</a>, <a href="/search/cond-mat?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/1007.2219">arXiv:1007.2219</a> <span> [<a href="https://arxiv.org/pdf/1007.2219">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> <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/PhysRevLett.106.060501">10.1103/PhysRevLett.106.060501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Demonstration of a Tuneable Coupler for Superconducting Qubits Using Coherent, Time Domain, Two-Qubit Operations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">R. C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Lenander%2C+M">M. Lenander</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A+D">A. D. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Weides%2C+M">M. Weides</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Yamamoto%2C+T">T. Yamamoto</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">J. M. Martinis</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="1007.2219v1-abstract-short" style="display: inline;"> A major challenge in the field of quantum computing is the construction of scalable qubit coupling architectures. Here, we demonstrate a novel tuneable coupling circuit that allows superconducting qubits to be coupled over long distances. We show that the inter-qubit coupling strength can be arbitrarily tuned over nanosecond timescales within a sequence that mimics actual use in an algorithm. The… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1007.2219v1-abstract-full').style.display = 'inline'; document.getElementById('1007.2219v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1007.2219v1-abstract-full" style="display: none;"> A major challenge in the field of quantum computing is the construction of scalable qubit coupling architectures. Here, we demonstrate a novel tuneable coupling circuit that allows superconducting qubits to be coupled over long distances. We show that the inter-qubit coupling strength can be arbitrarily tuned over nanosecond timescales within a sequence that mimics actual use in an algorithm. The coupler has a measured on/off ratio of 1000. The design is self-contained and physically separate from the qubits, allowing the coupler to be used as a module to connect a variety of elements such as qubits, resonators, amplifiers, and readout circuitry over long distances. Such design flexibility is likely to be essential for a scalable quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1007.2219v1-abstract-full').style.display = 'none'; document.getElementById('1007.2219v1-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 July, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2010. </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 manuscript pages, 4 manuscript figures, 3 supplementary information pages, 4 supplementary 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/0909.4585">arXiv:0909.4585</a> <span> [<a href="https://arxiv.org/pdf/0909.4585">pdf</a>, <a href="https://arxiv.org/ps/0909.4585">ps</a>, <a href="https://arxiv.org/format/0909.4585">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> </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.103.200404">10.1103/PhysRevLett.103.200404 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Decoherence Dynamics of Complex Photon States in a Superconducting Circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">R. C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A+D">A. D. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Weides%2C+M">M. Weides</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</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="0909.4585v1-abstract-short" style="display: inline;"> Quantum states inevitably decay with time into a probabilistic mixture of classical states, due to their interaction with the environment and measurement instrumentation. We present the first measurement of the decoherence dynamics of complex photon states in a condensed-matter system. By controllably preparing a number of distinct, quantum-superposed photon states in a superconducting microwave… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0909.4585v1-abstract-full').style.display = 'inline'; document.getElementById('0909.4585v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0909.4585v1-abstract-full" style="display: none;"> Quantum states inevitably decay with time into a probabilistic mixture of classical states, due to their interaction with the environment and measurement instrumentation. We present the first measurement of the decoherence dynamics of complex photon states in a condensed-matter system. By controllably preparing a number of distinct, quantum-superposed photon states in a superconducting microwave resonator, we show that the subsequent decay dynamics can be quantitatively described by taking into account only two distinct decay channels, energy relaxation and dephasing. Our ability to prepare specific initial quantum states allows us to measure the evolution of specific elements in the quantum density matrix, in a very detailed manner that can be compared with theory. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0909.4585v1-abstract-full').style.display = 'none'; document.getElementById('0909.4585v1-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, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2009. </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">4 pages, 4 figures, Supplementary movies can be downloaded at http://www.physics.ucsb.edu/~martinisgroup/movies.shtml</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 103, 200404 (2009) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0909.0547">arXiv:0909.0547</a> <span> [<a href="https://arxiv.org/pdf/0909.0547">pdf</a>, <a href="https://arxiv.org/ps/0909.0547">ps</a>, <a href="https://arxiv.org/format/0909.0547">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> </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/10.1063/1.3273372">10.1063/1.3273372 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Improving the Coherence Time of Superconducting Coplanar Resonators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">R. C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Lenander%2C+M">M. Lenander</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A+D">A. D. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Weides%2C+M">M. Weides</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</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="0909.0547v1-abstract-short" style="display: inline;"> The quality factor and energy decay time of superconducting resonators have been measured as a function of material, geometry, and magnetic field. Once the dissipation of trapped magnetic vortices is minimized, we identify surface two-level states (TLS) as an important decay mechanism. A wide gap between the center conductor and the ground plane, as well as use of the superconductor Re instead o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0909.0547v1-abstract-full').style.display = 'inline'; document.getElementById('0909.0547v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0909.0547v1-abstract-full" style="display: none;"> The quality factor and energy decay time of superconducting resonators have been measured as a function of material, geometry, and magnetic field. Once the dissipation of trapped magnetic vortices is minimized, we identify surface two-level states (TLS) as an important decay mechanism. A wide gap between the center conductor and the ground plane, as well as use of the superconductor Re instead of Al, are shown to decrease loss. We also demonstrate that classical measurements of resonator quality factor at low excitation power are consistent with single-photon decay time measured using qubit-resonator swap experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0909.0547v1-abstract-full').style.display = 'none'; document.getElementById('0909.0547v1-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 September, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2009. </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">3 pages, 4 figures for the main paper; total 5 pages, 6 figures including supplementary material. Submitted to Applied Physics Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 95, 233508 (2009) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0904.2171">arXiv:0904.2171</a> <span> [<a href="https://arxiv.org/pdf/0904.2171">pdf</a>, <a href="https://arxiv.org/ps/0904.2171">ps</a>, <a href="https://arxiv.org/format/0904.2171">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> </div> </div> <p class="title is-5 mathjax"> Energy Decay in Josephson Qubits from Non-equilibrium Quasiparticles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Aumentado%2C+J">J. Aumentado</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="0904.2171v2-abstract-short" style="display: inline;"> We calculate the energy decay rate of Josephson qubits and superconducting resonators from non-equilibrium quasiparticles. The decay rates from experiments are shown to be consistent with predictions based on a prior measurement of the quasiparticle density n_qp = 10/um^3, which suggests that non-equilibrium quasiparticles are an important decoherence source for Josephson qubits. Calculations of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0904.2171v2-abstract-full').style.display = 'inline'; document.getElementById('0904.2171v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0904.2171v2-abstract-full" style="display: none;"> We calculate the energy decay rate of Josephson qubits and superconducting resonators from non-equilibrium quasiparticles. The decay rates from experiments are shown to be consistent with predictions based on a prior measurement of the quasiparticle density n_qp = 10/um^3, which suggests that non-equilibrium quasiparticles are an important decoherence source for Josephson qubits. Calculations of the energy-decay and diffusion of quasiparticles also indicate that prior engineered gap and trap structures, which reduce the density of quasiparticles, should be redesigned to improve their efficacy. This model also explains a striking feature in Josephson qubits and resonators - a small reduction in decay rate with increasing temperature. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0904.2171v2-abstract-full').style.display = 'none'; document.getElementById('0904.2171v2-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 August, 2009; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 April, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2009. </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">4 pages, 3 figures, a supplementary calculation is at arXiv:0904.2035; Accepted for publication in PRL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0808.3279">arXiv:0808.3279</a> <span> [<a href="https://arxiv.org/pdf/0808.3279">pdf</a>, <a href="https://arxiv.org/ps/0808.3279">ps</a>, <a href="https://arxiv.org/format/0808.3279">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> </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.101.240401">10.1103/PhysRevLett.101.240401 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement of the decay of Fock states in a superconducting quantum circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">R. C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A+D">A. D. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</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="0808.3279v1-abstract-short" style="display: inline;"> We demonstrate the controlled generation of Fock states with up to 15 photons in a microwave coplanar waveguide resonator coupled to a superconducting phase qubit. The subsequent decay of the Fock states, due to dissipation, is then monitored by varying the time delay between preparing the state and performing a number-state analysis. We find that the decay dynamics can be described by a master… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0808.3279v1-abstract-full').style.display = 'inline'; document.getElementById('0808.3279v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0808.3279v1-abstract-full" style="display: none;"> We demonstrate the controlled generation of Fock states with up to 15 photons in a microwave coplanar waveguide resonator coupled to a superconducting phase qubit. The subsequent decay of the Fock states, due to dissipation, is then monitored by varying the time delay between preparing the state and performing a number-state analysis. We find that the decay dynamics can be described by a master equation where the lifetime of the n-photon Fock state scales as 1/n, in agreement with theory. We have also generated a coherent state in the microwave resonator, and monitored its decay process. We demonstrate that the coherent state maintains a Poisson distribution as it decays, with an average photon number that decreases with the same characteristic decay time as the one-photon Fock state. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0808.3279v1-abstract-full').style.display = 'none'; document.getElementById('0808.3279v1-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, 2008; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2008. </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">4 pages, 5 figures, and 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 101, 240401 (2008) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0806.3547">arXiv:0806.3547</a> <span> [<a href="https://arxiv.org/pdf/0806.3547">pdf</a>, <a href="https://arxiv.org/ps/0806.3547">ps</a>, <a href="https://arxiv.org/format/0806.3547">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.101.200401">10.1103/PhysRevLett.101.200401 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Uncollapsing of a quantum state in a superconducting phase qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Katz%2C+N">Nadav Katz</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">Matthew Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">Radoslaw C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A">A. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">Alexander N. 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="0806.3547v1-abstract-short" style="display: inline;"> We demonstrate in a superconducting qubit the conditional recovery ("uncollapsing") of a quantum state after a partial-collapse measurement. A weak measurement extracts information and results in a non-unitary transformation of the qubit state. However, by adding a rotation and a second partial measurement with the same strength, we erase the extracted information, effectively canceling the effe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0806.3547v1-abstract-full').style.display = 'inline'; document.getElementById('0806.3547v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0806.3547v1-abstract-full" style="display: none;"> We demonstrate in a superconducting qubit the conditional recovery ("uncollapsing") of a quantum state after a partial-collapse measurement. A weak measurement extracts information and results in a non-unitary transformation of the qubit state. However, by adding a rotation and a second partial measurement with the same strength, we erase the extracted information, effectively canceling the effect of both measurements. The fidelity of the state recovery is measured using quantum process tomography and found to be above 70% for partial-collapse strength less than 0.6. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0806.3547v1-abstract-full').style.display = 'none'; document.getElementById('0806.3547v1-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 June, 2008; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2008. </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">4 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 101, 200401 (2008) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0802.2404">arXiv:0802.2404</a> <span> [<a href="https://arxiv.org/pdf/0802.2404">pdf</a>, <a href="https://arxiv.org/ps/0802.2404">ps</a>, <a href="https://arxiv.org/format/0802.2404">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> </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/10.1063/1.2898887">10.1063/1.2898887 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A+D">Aaron D. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">R. C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Katz%2C+N">N. Katz</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=McKenney%2C+C">C. McKenney</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Weig%2C+E+M">E. M. Weig</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">J. M. Martinis</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="0802.2404v1-abstract-short" style="display: inline;"> The microwave performance of amorphous dielectric materials at very low temperatures and very low excitation strengths displays significant excess loss. Here, we present the loss tangents of some common amorphous and crystalline dielectrics, measured at low temperatures (T < 100 mK) with near single-photon excitation energies, using both coplanar waveguide (CPW) and lumped LC resonators. The los… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0802.2404v1-abstract-full').style.display = 'inline'; document.getElementById('0802.2404v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0802.2404v1-abstract-full" style="display: none;"> The microwave performance of amorphous dielectric materials at very low temperatures and very low excitation strengths displays significant excess loss. Here, we present the loss tangents of some common amorphous and crystalline dielectrics, measured at low temperatures (T < 100 mK) with near single-photon excitation energies, using both coplanar waveguide (CPW) and lumped LC resonators. The loss can be understood using a two-level state (TLS) defect model. A circuit analysis of the half-wavelength resonators we used is outlined, and the energy dissipation of such a resonator on a multilayered dielectric substrate is considered theoretically. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0802.2404v1-abstract-full').style.display = 'none'; document.getElementById('0802.2404v1-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 February, 2008; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2008. </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">4 pages, 3 figures, submitted to Applied Physics Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0801.2994">arXiv:0801.2994</a> <span> [<a href="https://arxiv.org/pdf/0801.2994">pdf</a>, <a href="https://arxiv.org/ps/0801.2994">ps</a>, <a href="https://arxiv.org/format/0801.2994">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> </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.77.180508">10.1103/PhysRevB.77.180508 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Transformed Dissipation in Superconducting Quantum Circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">Matthew Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">Radoslaw C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Katz%2C+N">N. Katz</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A">A. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</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="0801.2994v2-abstract-short" style="display: inline;"> Superconducting quantum circuits must be designed carefully to avoid dissipation from coupling to external control circuitry. Here we introduce the concept of current transformation to quantify coupling to the environment. We test this theory with an experimentally-determined impedance transformation of $\sim 10^5$ and find quantitative agreement better than a factor of 2 between this transforma… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0801.2994v2-abstract-full').style.display = 'inline'; document.getElementById('0801.2994v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0801.2994v2-abstract-full" style="display: none;"> Superconducting quantum circuits must be designed carefully to avoid dissipation from coupling to external control circuitry. Here we introduce the concept of current transformation to quantify coupling to the environment. We test this theory with an experimentally-determined impedance transformation of $\sim 10^5$ and find quantitative agreement better than a factor of 2 between this transformation and the reduced lifetime of a phase qubit coupled to a tunable transformer. Higher-order corrections from quantum fluctuations are also calculated with this theory, but found not to limit the qubit lifetime. We also illustrate how this simple connection between current and impedance transformation can be used to rule out dissipation sources in experimental qubit systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0801.2994v2-abstract-full').style.display = 'none'; document.getElementById('0801.2994v2-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, 2008; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 January, 2008; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2008. </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">4 pages, 4 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 77, 180508(R) (2008) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0708.2125">arXiv:0708.2125</a> <span> [<a href="https://arxiv.org/pdf/0708.2125">pdf</a>, <a href="https://arxiv.org/format/0708.2125">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> </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.99.187006">10.1103/PhysRevLett.99.187006 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> 1/f Flux Noise in Josephson Phase Qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">Radoslaw C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=McDermott%2C+R">R. McDermott</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Hofheinz%2C+M">M. Hofheinz</a>, <a href="/search/cond-mat?searchtype=author&query=Katz%2C+N">N. Katz</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">Matthew Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Connell%2C+A+D">A. D. O'Connell</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</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="0708.2125v1-abstract-short" style="display: inline;"> We present a new method to measure 1/f noise in Josephson quantum bits (qubits) that yields low-frequency spectra below 1Hz. Comparison of noise taken at positive and negative bias of a phase qubit shows the dominant noise source to be flux noise and not junction critical-current noise, with a magnitude similar to that measured previously in other systems. Theoretical calculations show that the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0708.2125v1-abstract-full').style.display = 'inline'; document.getElementById('0708.2125v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0708.2125v1-abstract-full" style="display: none;"> We present a new method to measure 1/f noise in Josephson quantum bits (qubits) that yields low-frequency spectra below 1Hz. Comparison of noise taken at positive and negative bias of a phase qubit shows the dominant noise source to be flux noise and not junction critical-current noise, with a magnitude similar to that measured previously in other systems. Theoretical calculations show that the level of flux noise is not compatible with the standard model of noise from two-level state defects in the surface oxides of the films. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0708.2125v1-abstract-full').style.display = 'none'; document.getElementById('0708.2125v1-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, 2007; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2007. </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">4 pages, 3 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/0705.0095">arXiv:0705.0095</a> <span> [<a href="https://arxiv.org/pdf/0705.0095">pdf</a>, <a href="https://arxiv.org/ps/0705.0095">ps</a>, <a href="https://arxiv.org/format/0705.0095">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> </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.99.170504">10.1103/PhysRevLett.99.170504 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Temperature dependence of coherent oscillations in Josephson phase qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lisenfeld%2C+J">J. Lisenfeld</a>, <a href="/search/cond-mat?searchtype=author&query=Lukashenko%2C+A">A. Lukashenko</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">J. M. Martinis</a>, <a href="/search/cond-mat?searchtype=author&query=Ustinov%2C+A+V">A. V. Ustinov</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="0705.0095v1-abstract-short" style="display: inline;"> We experimentally investigate the temperature dependence of Rabi oscillations and Ramsey fringes in superconducting phase qubits driven by microwave pulses. In a wide range of temperatures, we find that both the decay time and the amplitude of these coherent oscillations remain nearly unaffected by thermal fluctuations. The oscillations are observed well above the crossover temperature from ther… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0705.0095v1-abstract-full').style.display = 'inline'; document.getElementById('0705.0095v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0705.0095v1-abstract-full" style="display: none;"> We experimentally investigate the temperature dependence of Rabi oscillations and Ramsey fringes in superconducting phase qubits driven by microwave pulses. In a wide range of temperatures, we find that both the decay time and the amplitude of these coherent oscillations remain nearly unaffected by thermal fluctuations. The oscillations are observed well above the crossover temperature from thermally activated escape to quantum tunneling for undriven qubits. In the two-level limit, coherent qubit response rapidly vanishes as soon as the energy of thermal fluctuations kT becomes larger than the energy level spacing of the qubit. Our observations shed new light on the origin of decoherence in superconducting qubits. The experimental data suggest that, without degrading already achieved coherence times, phase qubits can be operated at temperatures much higher than those reported till now. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0705.0095v1-abstract-full').style.display = 'none'; document.getElementById('0705.0095v1-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 May, 2007; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2007. </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">4 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/cond-mat/0602432">arXiv:cond-mat/0602432</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0602432">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0602432">ps</a>, <a href="https://arxiv.org/format/cond-mat/0602432">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> </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.97.050502">10.1103/PhysRevLett.97.050502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> State tomography of capacitively shunted phase qubits with high fidelity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Steffen%2C+M">Matthias Steffen</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">M. Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=McDermott%2C+R">R. McDermott</a>, <a href="/search/cond-mat?searchtype=author&query=Katz%2C+N">N. Katz</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R+C">Radoslaw C. Bialczak</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">Matthew Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Weig%2C+E+M">E. M. Weig</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</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="cond-mat/0602432v1-abstract-short" style="display: inline;"> We introduce a new design concept for superconducting quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance. The number of two-level systems (TLS) that couple to the qubit is thereby reduced by an order of magnitude and the measurement fidelity improves to 90%. This improved design enables the first demonstr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0602432v1-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0602432v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0602432v1-abstract-full" style="display: none;"> We introduce a new design concept for superconducting quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance. The number of two-level systems (TLS) that couple to the qubit is thereby reduced by an order of magnitude and the measurement fidelity improves to 90%. This improved design enables the first demonstration of quantum state tomography with superconducting qubits using single shot measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0602432v1-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0602432v1-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 February, 2006; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2006. </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">submitted to PRL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/cond-mat/0507622">arXiv:cond-mat/0507622</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0507622">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0507622">ps</a>, <a href="https://arxiv.org/format/cond-mat/0507622">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</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.95.210503">10.1103/PhysRevLett.95.210503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Decoherence in Josephson Qubits from Dielectric Loss </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Martinis%2C+J+M">John M. Martinis</a>, <a href="/search/cond-mat?searchtype=author&query=Cooper%2C+K+B">K. B. Cooper</a>, <a href="/search/cond-mat?searchtype=author&query=McDermott%2C+R">R. McDermott</a>, <a href="/search/cond-mat?searchtype=author&query=Steffen%2C+M">Matthias Steffen</a>, <a href="/search/cond-mat?searchtype=author&query=Ansmann%2C+M">Markus Ansmann</a>, <a href="/search/cond-mat?searchtype=author&query=Osborn%2C+K">K. Osborn</a>, <a href="/search/cond-mat?searchtype=author&query=Cicak%2C+K">K. Cicak</a>, <a href="/search/cond-mat?searchtype=author&query=Oh%2C+S">S. Oh</a>, <a href="/search/cond-mat?searchtype=author&query=Pappas%2C+D+P">D. P. Pappas</a>, <a href="/search/cond-mat?searchtype=author&query=Simmonds%2C+R+W">R. W. Simmonds</a>, <a href="/search/cond-mat?searchtype=author&query=Yu%2C+c+C">clare C. Yu</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="cond-mat/0507622v1-abstract-short" style="display: inline;"> Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the tunnel junction can lead to short coherence times. We show that a variety of microwave and qubit measurements are well modeled by loss from resonant absorption of two-level defects. Our results demonstr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0507622v1-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0507622v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0507622v1-abstract-full" style="display: none;"> Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the tunnel junction can lead to short coherence times. We show that a variety of microwave and qubit measurements are well modeled by loss from resonant absorption of two-level defects. Our results demonstrate that this loss can be significantly reduced by using better dielectrics and fabricating junctions of small area $\lesssim 10 渭\textrm{m}^2$. With a redesigned phase qubit employing low-loss dielectrics, the energy relaxation rate has been improved by a factor of 20, opening up the possibility of multi-qubit gates and algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0507622v1-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0507622v1-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 July, 2005; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2005. </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">shortened version submitted to PRL</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a 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