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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=Martinis%2C+J+M&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Martinis%2C+J+M&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Martinis%2C+J+M&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/2110.02481">arXiv:2110.02481</a> <span> [<a href="https://arxiv.org/pdf/2110.02481">pdf</a>, <a href="https://arxiv.org/format/2110.02481">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Emerging Technologies">cs.ET</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="Distributed, Parallel, and Cluster Computing">cs.DC</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/s41928-022-00774-2">10.1038/s41928-022-00774-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Massively Parallel Probabilistic Computing with Sparse Ising Machines </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Aadit%2C+N+A">Navid Anjum Aadit</a>, <a href="/search/cond-mat?searchtype=author&query=Grimaldi%2C+A">Andrea Grimaldi</a>, <a href="/search/cond-mat?searchtype=author&query=Carpentieri%2C+M">Mario Carpentieri</a>, <a href="/search/cond-mat?searchtype=author&query=Theogarajan%2C+L">Luke Theogarajan</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=Finocchio%2C+G">Giovanni Finocchio</a>, <a href="/search/cond-mat?searchtype=author&query=Camsari%2C+K+Y">Kerem Y. Camsari</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="2110.02481v2-abstract-short" style="display: inline;"> Inspired by the developments in quantum computing, building domain-specific classical hardware to solve computationally hard problems has received increasing attention. Here, by introducing systematic sparsification techniques, we demonstrate a massively parallel architecture: the sparse Ising Machine (sIM). Exploiting sparsity, sIM achieves ideal parallelism: its key figure of merit - flips per s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.02481v2-abstract-full').style.display = 'inline'; document.getElementById('2110.02481v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.02481v2-abstract-full" style="display: none;"> Inspired by the developments in quantum computing, building domain-specific classical hardware to solve computationally hard problems has received increasing attention. Here, by introducing systematic sparsification techniques, we demonstrate a massively parallel architecture: the sparse Ising Machine (sIM). Exploiting sparsity, sIM achieves ideal parallelism: its key figure of merit - flips per second - scales linearly with the number of probabilistic bits (p-bit) in the system. This makes sIM up to 6 orders of magnitude faster than a CPU implementing standard Gibbs sampling. Compared to optimized implementations in TPUs and GPUs, sIM delivers 5-18x speedup in sampling. In benchmark problems such as integer factorization, sIM can reliably factor semiprimes up to 32-bits, far larger than previous attempts from D-Wave and other probabilistic solvers. Strikingly, sIM beats competition-winning SAT solvers (by 4-700x in runtime to reach 95% accuracy) in solving 3SAT problems. Even when sampling is made inexact using faster clocks, sIM can find the correct ground state with further speedup. The problem encoding and sparsification techniques we introduce can be applied to other Ising Machines (classical and quantum) and the architecture we present can be used for scaling the demonstrated 5,000-10,000 p-bits to 1,000,000 or more through analog CMOS or nanodevices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.02481v2-abstract-full').style.display = 'none'; document.getElementById('2110.02481v2-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 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Electronics (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.14270">arXiv:2012.14270</a> <span> [<a href="https://arxiv.org/pdf/2012.14270">pdf</a>, <a href="https://arxiv.org/ps/2012.14270">ps</a>, <a href="https://arxiv.org/format/2012.14270">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> <p class="title is-5 mathjax"> Information Constraints for Scalable Control in a Quantum Computer </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> </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="2012.14270v1-abstract-short" style="display: inline;"> When working to understand quantum systems engineering, there are many constraints to building a scalable quantum computer. Here I discuss a constraint on the qubit control system from an information point of view, showing that the large amount of information needed for the control system will put significant constraints on the control system. The size the qubits is conjectured to be an important… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.14270v1-abstract-full').style.display = 'inline'; document.getElementById('2012.14270v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.14270v1-abstract-full" style="display: none;"> When working to understand quantum systems engineering, there are many constraints to building a scalable quantum computer. Here I discuss a constraint on the qubit control system from an information point of view, showing that the large amount of information needed for the control system will put significant constraints on the control system. The size the qubits is conjectured to be an important systems parameter. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.14270v1-abstract-full').style.display = 'none'; document.getElementById('2012.14270v1-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> 16 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">1 page</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.06137">arXiv:2012.06137</a> <span> [<a href="https://arxiv.org/pdf/2012.06137">pdf</a>, <a href="https://arxiv.org/format/2012.06137">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> <p class="title is-5 mathjax"> Saving superconducting quantum processors from qubit decay and correlated errors generated by gamma and cosmic rays </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> </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="2012.06137v3-abstract-short" style="display: inline;"> Error-corrected quantum computers can only work if errors are small and uncorrelated. Here I show how cosmic rays or stray background radiation affects superconducting qubits by modeling the phonon to electron/quasiparticle down-conversion physics. For present designs, the model predicts about 57\% of the radiation energy breaks Cooper pairs into quasiparticles, which then vigorously suppress the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.06137v3-abstract-full').style.display = 'inline'; document.getElementById('2012.06137v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.06137v3-abstract-full" style="display: none;"> Error-corrected quantum computers can only work if errors are small and uncorrelated. Here I show how cosmic rays or stray background radiation affects superconducting qubits by modeling the phonon to electron/quasiparticle down-conversion physics. For present designs, the model predicts about 57\% of the radiation energy breaks Cooper pairs into quasiparticles, which then vigorously suppress the qubit energy relaxation time ($T_1 \sim$ 160 ns) over a large area (cm) and for a long time (ms). Such large and correlated decay kills error correction. Using this quantitative model, I show how this energy can be channeled away from the qubit so that this error mechanism can be reduced by many orders of magnitude. I also comment on how this affects other solid-state qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.06137v3-abstract-full').style.display = 'none'; document.getElementById('2012.06137v3-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">9 pages, 9 figures, 4 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.08246">arXiv:1911.08246</a> <span> [<a href="https://arxiv.org/pdf/1911.08246">pdf</a>, <a href="https://arxiv.org/format/1911.08246">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="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/10.1038/s41598-020-59749-y">10.1038/s41598-020-59749-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Resolving the positions of defects in superconducting quantum bits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">Anthony Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Klimov%2C+P">Paul Klimov</a>, <a href="/search/cond-mat?searchtype=author&query=Weiss%2C+G">Georg Weiss</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=Ustinov%2C+A+V">Alexey V. Ustinov</a>, <a href="/search/cond-mat?searchtype=author&query=Lisenfeld%2C+J">J眉rgen Lisenfeld</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="1911.08246v2-abstract-short" style="display: inline;"> Solid-state quantum coherent devices are quickly progressing. Superconducting circuits, for instance, have already been used to demonstrate prototype quantum processors comprising a few tens of quantum bits. This development also revealed that a major part of decoherence and energy loss in such devices originates from a bath of parasitic material defects. However, neither the microscopic structure… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.08246v2-abstract-full').style.display = 'inline'; document.getElementById('1911.08246v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.08246v2-abstract-full" style="display: none;"> Solid-state quantum coherent devices are quickly progressing. Superconducting circuits, for instance, have already been used to demonstrate prototype quantum processors comprising a few tens of quantum bits. This development also revealed that a major part of decoherence and energy loss in such devices originates from a bath of parasitic material defects. However, neither the microscopic structure of defects nor the mechanisms by which they emerge during sample fabrication are understood. Here, we present a technique to obtain information on locations of defects relative to the thin film edge of the qubit circuit. Resonance frequencies of defects are tuned by exposing the qubit sample to electric fields generated by electrodes surrounding the chip. By determining the defect's coupling strength to each electrode and comparing it to a simulation of the field distribution, we obtain the probability at which location and at which interface the defect resides. This method is applicable to already existing samples of various qubit types, without further on-chip design changes. It provides a valuable tool for improving the material quality and nano-fabrication procedures towards more coherent quantum circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.08246v2-abstract-full').style.display = 'none'; document.getElementById('1911.08246v2-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 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1909.09749">arXiv:1909.09749</a> <span> [<a href="https://arxiv.org/pdf/1909.09749">pdf</a>, <a href="https://arxiv.org/format/1909.09749">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="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/s41534-019-0224-1">10.1038/s41534-019-0224-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electric field spectroscopy of material defects in transmon qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lisenfeld%2C+J">J眉rgen Lisenfeld</a>, <a href="/search/cond-mat?searchtype=author&query=Bilmes%2C+A">Alexander Bilmes</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">Anthony Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">Rami Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Klimov%2C+P">Paul Klimov</a>, <a href="/search/cond-mat?searchtype=author&query=Weiss%2C+G">Georg Weiss</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=Ustinov%2C+A+V">Alexey 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="1909.09749v2-abstract-short" style="display: inline;"> Superconducting integrated circuits have demonstrated a tremendous potential to realize integrated quantum computing processors. However, the downside of the solid-state approach is that superconducting qubits suffer strongly from energy dissipation and environmental fluctuations caused by atomic-scale defects in device materials. Further progress towards upscaled quantum processors will require i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.09749v2-abstract-full').style.display = 'inline'; document.getElementById('1909.09749v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1909.09749v2-abstract-full" style="display: none;"> Superconducting integrated circuits have demonstrated a tremendous potential to realize integrated quantum computing processors. However, the downside of the solid-state approach is that superconducting qubits suffer strongly from energy dissipation and environmental fluctuations caused by atomic-scale defects in device materials. Further progress towards upscaled quantum processors will require improvements in device fabrication techniques which need to be guided by novel analysis methods to understand and prevent mechanisms of defect formation. Here, we present a new technique to analyse individual defects in superconducting qubits by tuning them with applied electric fields. This provides a new spectroscopy method to extract the defects' energy distribution, electric dipole moments, and coherence times. Moreover, it enables one to distinguish defects residing in Josephson junction tunnel barriers from those at circuit interfaces. We find that defects at circuit interfaces are responsible for about 60% of the dielectric loss in the investigated transmon qubit sample. About 40% of all detected defects are contained in the tunnel barriers of the large-area parasitic Josephson junctions that occur collaterally in shadow evaporation, and only about 3% are identified as strongly coupled defects which presumably reside in the small-area qubit tunnel junctions. The demonstrated technique provides a valuable tool to assess the decoherence sources related to circuit interfaces and to tunnel junctions that is readily applicable to standard qubit samples. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.09749v2-abstract-full').style.display = 'none'; document.getElementById('1909.09749v2-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 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">Including Supplementary Information and Supplementary 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 5, 105 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1712.01671">arXiv:1712.01671</a> <span> [<a href="https://arxiv.org/pdf/1712.01671">pdf</a>, <a href="https://arxiv.org/format/1712.01671">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="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/10.1063/1.5014033">10.1063/1.5014033 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Low Loss Multi-Layer Wiring for Superconducting Microwave Devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</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">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A">A. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Foxen%2C+B">B. Foxen</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Klimov%2C+P+V">P. V. Klimov</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Neven%2C+H">H. Neven</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="1712.01671v2-abstract-short" style="display: inline;"> Complex integrated circuits require multiple wiring layers. In complementary metal-oxide-semiconductor (CMOS) processing, these layers are robustly separated by amorphous dielectrics. These dielectrics would dominate energy loss in superconducting integrated circuits. Here we demonstrate a procedure that capitalizes on the structural benefits of inter-layer dielectrics during fabrication and mitig… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.01671v2-abstract-full').style.display = 'inline'; document.getElementById('1712.01671v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1712.01671v2-abstract-full" style="display: none;"> Complex integrated circuits require multiple wiring layers. In complementary metal-oxide-semiconductor (CMOS) processing, these layers are robustly separated by amorphous dielectrics. These dielectrics would dominate energy loss in superconducting integrated circuits. Here we demonstrate a procedure that capitalizes on the structural benefits of inter-layer dielectrics during fabrication and mitigates the added loss. We separate and support multiple wiring layers throughout fabrication using SiO$_2$ scaffolding, then remove it post-fabrication. This technique is compatible with foundry level processing and the can be generalized to make many different forms of low-loss multi-layer wiring. We use this technique to create freestanding aluminum vacuum gap crossovers (airbridges). We characterize the added capacitive loss of these airbridges by connecting ground planes over microwave frequency $位/4$ coplanar waveguide resonators and measuring resonator loss. We measure a low power resonator loss of $\sim 3.9 \times 10^{-8}$ per bridge, which is 100 times lower than dielectric supported bridges. We further characterize these airbridges as crossovers, control line jumpers, and as part of a coupling network in gmon and fuxmon qubits. We measure qubit characteristic lifetimes ($T_1$'s) in excess of 30 $渭$s in gmon devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1712.01671v2-abstract-full').style.display = 'none'; document.getElementById('1712.01671v2-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 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 December, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2017. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.08752">arXiv:1608.08752</a> <span> [<a href="https://arxiv.org/pdf/1608.08752">pdf</a>, <a href="https://arxiv.org/format/1608.08752">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/10.1103/PhysRevLett.118.057702">10.1103/PhysRevLett.118.057702 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C+M">C. M. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Petukhov%2C+A+G">A. G. Petukhov</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Kafri%2C+D">Dvir Kafri</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Graff%2C+R">R. Graff</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Shabani%2C+A">A. Shabani</a>, <a href="/search/cond-mat?searchtype=author&query=Smelyanskiy%2C+V+N">V. N. Smelyanskiy</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a> , et al. (3 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="1608.08752v2-abstract-short" style="display: inline;"> By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its two-sided environmental flux noise spectral density over a range of frequencies around $2k_BT/h \approx 1\,\rm{GHz}$, allowing for the observation of a classical-quantum crossover. Below the crossover point, the symmetric noise component follows a $1/f$ power law that matches the magnitude of the $1/f$… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08752v2-abstract-full').style.display = 'inline'; document.getElementById('1608.08752v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.08752v2-abstract-full" style="display: none;"> By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its two-sided environmental flux noise spectral density over a range of frequencies around $2k_BT/h \approx 1\,\rm{GHz}$, allowing for the observation of a classical-quantum crossover. Below the crossover point, the symmetric noise component follows a $1/f$ power law that matches the magnitude of the $1/f$ noise near $1\,{\rm{Hz}}$. The antisymmetric component displays a 1/T dependence below $100\,\rm{mK}$, providing dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.08752v2-abstract-full').style.display = 'none'; document.getElementById('1608.08752v2-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 September, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </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">paper + supplement</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 118, 057702 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1607.05841">arXiv:1607.05841</a> <span> [<a href="https://arxiv.org/pdf/1607.05841">pdf</a>, <a href="https://arxiv.org/format/1607.05841">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/10.1088/0953-2048/29/10/104006">10.1088/0953-2048/29/10/104006 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dielectric surface loss in superconducting resonators with flux-trapping holes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A">A. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+C">I. C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</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="1607.05841v2-abstract-short" style="display: inline;"> Surface distributions of two level system (TLS) defects and magnetic vortices are limiting dissipation sources in superconducting quantum circuits. Arrays of flux-trapping holes are commonly used to eliminate loss due to magnetic vortices, but may increase dielectric TLS loss. We find that dielectric TLS loss increases by approximately 25% for resonators with a hole array beginning 2 $渭\text{m}$ f… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05841v2-abstract-full').style.display = 'inline'; document.getElementById('1607.05841v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1607.05841v2-abstract-full" style="display: none;"> Surface distributions of two level system (TLS) defects and magnetic vortices are limiting dissipation sources in superconducting quantum circuits. Arrays of flux-trapping holes are commonly used to eliminate loss due to magnetic vortices, but may increase dielectric TLS loss. We find that dielectric TLS loss increases by approximately 25% for resonators with a hole array beginning 2 $渭\text{m}$ from the resonator edge, while the dielectric loss added by holes further away was below measurement sensitivity. Other forms of loss were not affected by the holes. Additionally, we estimate the loss due to residual magnetic effects to be $9\times 10^{-10} /渭\text{T} $ for resonators patterned with flux-traps and operated in magnetic fields up to $5$ $渭\text{T}$. This is orders of magnitude below the total loss of the best superconducting coplanar waveguide resonators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05841v2-abstract-full').style.display = 'none'; document.getElementById('1607.05841v2-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> 29 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 July, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2016. </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, 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/1511.03316">arXiv:1511.03316</a> <span> [<a href="https://arxiv.org/pdf/1511.03316">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/10.1038/nature17658">10.1038/nature17658 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Digitized adiabatic quantum computing with a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Shabani%2C+A">A. Shabani</a>, <a href="/search/cond-mat?searchtype=author&query=Lamata%2C+L">L. Lamata</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Mezzacapo%2C+A">A. Mezzacapo</a>, <a href="/search/cond-mat?searchtype=author&query=Heras%2C+U+L">U. Las Heras</a>, <a href="/search/cond-mat?searchtype=author&query=Babbush%2C+R">R. Babbush</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a> , et al. (4 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="1511.03316v1-abstract-short" style="display: inline;"> A major challenge in quantum computing is to solve general problems with limited physical hardware. Here, we implement digitized adiabatic quantum computing, combining the generality of the adiabatic algorithm with the universality of the digital approach, using a superconducting circuit with nine qubits. We probe the adiabatic evolutions, and quantify the success of the algorithm for random spin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.03316v1-abstract-full').style.display = 'inline'; document.getElementById('1511.03316v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1511.03316v1-abstract-full" style="display: none;"> A major challenge in quantum computing is to solve general problems with limited physical hardware. Here, we implement digitized adiabatic quantum computing, combining the generality of the adiabatic algorithm with the universality of the digital approach, using a superconducting circuit with nine qubits. We probe the adiabatic evolutions, and quantify the success of the algorithm for random spin problems. We find that the system can approximate the solutions to both frustrated Ising problems and problems with more complex interactions, with a performance that is comparable. The presented approach is compatible with small-scale systems as well as future error-corrected quantum computers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1511.03316v1-abstract-full').style.display = 'none'; document.getElementById('1511.03316v1-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, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2015. </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. Supplementary: 12 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 534, 222-226 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1509.05470">arXiv:1509.05470</a> <span> [<a href="https://arxiv.org/pdf/1509.05470">pdf</a>, <a href="https://arxiv.org/format/1509.05470">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.116.020501">10.1103/PhysRevLett.116.020501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measuring and Suppressing Quantum State Leakage in a Superconducting Qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Zijun Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">Chris Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A">A. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</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="1509.05470v2-abstract-short" style="display: inline;"> Leakage errors occur when a quantum system leaves the two-level qubit subspace. Reducing these errors is critically important for quantum error correction to be viable. To quantify leakage errors, we use randomized benchmarking in conjunction with measurement of the leakage population. We characterize single qubit gates in a superconducting qubit, and by refining our use of Derivative Reduction by… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.05470v2-abstract-full').style.display = 'inline'; document.getElementById('1509.05470v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1509.05470v2-abstract-full" style="display: none;"> Leakage errors occur when a quantum system leaves the two-level qubit subspace. Reducing these errors is critically important for quantum error correction to be viable. To quantify leakage errors, we use randomized benchmarking in conjunction with measurement of the leakage population. We characterize single qubit gates in a superconducting qubit, and by refining our use of Derivative Reduction by Adiabatic Gate (DRAG) pulse shaping along with detuning of the pulses, we obtain gate errors consistently below $10^{-3}$ and leakage rates at the $10^{-5}$ level. With the control optimized, we find that a significant portion of the remaining leakage is due to incoherent heating of the qubit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.05470v2-abstract-full').style.display = 'none'; document.getElementById('1509.05470v2-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 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2015. </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 including supplement; fixed typos in metadata</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 116, 020501 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1505.04990">arXiv:1505.04990</a> <span> [<a href="https://arxiv.org/pdf/1505.04990">pdf</a>, <a href="https://arxiv.org/ps/1505.04990">ps</a>, <a href="https://arxiv.org/format/1505.04990">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> <p class="title is-5 mathjax"> Universal quantum simulation with prethreshold superconducting qubits: Single-excitation subspace method </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Geller%2C+M+R">Michael R. Geller</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=Sornborger%2C+A+T">Andrew T. Sornborger</a>, <a href="/search/cond-mat?searchtype=author&query=Stancil%2C+P+C">Phillip C. Stancil</a>, <a href="/search/cond-mat?searchtype=author&query=Pritchett%2C+E+J">Emily J. Pritchett</a>, <a href="/search/cond-mat?searchtype=author&query=You%2C+H">Hao You</a>, <a href="/search/cond-mat?searchtype=author&query=Galiautdinov%2C+A">Andrei Galiautdinov</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="1505.04990v2-abstract-short" style="display: inline;"> Current quantum computing architectures lack the size and fidelity required for universal fault-tolerant operation, limiting the practical implementation of key quantum algorithms to all but the smallest problem sizes. In this work we propose an alternative method for general-purpose quantum computation that is ideally suited for such "prethreshold" superconducting hardware. Computations are perfo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.04990v2-abstract-full').style.display = 'inline'; document.getElementById('1505.04990v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.04990v2-abstract-full" style="display: none;"> Current quantum computing architectures lack the size and fidelity required for universal fault-tolerant operation, limiting the practical implementation of key quantum algorithms to all but the smallest problem sizes. In this work we propose an alternative method for general-purpose quantum computation that is ideally suited for such "prethreshold" superconducting hardware. Computations are performed in the n-dimensional single-excitation subspace (SES) of a system of n tunably coupled superconducting qubits. The approach is not scalable, but allows many operations in the unitary group SU(n) to be implemented by a single application of the Hamiltonian, bypassing the need to decompose a desired unitary into elementary gates. This feature makes large, nontrivial quantum computations possible within the available coherence time. We show how to use a programmable SES chip to perform fast amplitude amplification and phase estimation, two versatile quantum subalgorithms. We also show that an SES processor is well suited for Hamiltonian simulation, specifically simulation of the Schrodinger equation with a real but otherwise arbitrary nxn Hamiltonian matrix. We discuss the utility and practicality of such a universal quantum simulator, and propose its application to the study of realistic atomic and molecular collisions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.04990v2-abstract-full').style.display = 'none'; document.getElementById('1505.04990v2-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 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2015. </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</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A 91,062309 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1504.02707">arXiv:1504.02707</a> <span> [<a href="https://arxiv.org/pdf/1504.02707">pdf</a>, <a href="https://arxiv.org/format/1504.02707">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> <p class="title is-5 mathjax"> Preserving entanglement during weak measurement demonstrated with a violation of the Bell-Leggett-Garg inequality </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=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Dressel%2C+J">J. Dressel</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</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="1504.02707v2-abstract-short" style="display: inline;"> Weak measurement has provided new insight into the nature of quantum measurement, by demonstrating the ability to extract average state information without fully projecting the system. For single qubit measurements, this partial projection has been demonstrated with violations of the Leggett-Garg inequality. Here we investigate the effects of weak measurement on a maximally entangled Bell state th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.02707v2-abstract-full').style.display = 'inline'; document.getElementById('1504.02707v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1504.02707v2-abstract-full" style="display: none;"> Weak measurement has provided new insight into the nature of quantum measurement, by demonstrating the ability to extract average state information without fully projecting the system. For single qubit measurements, this partial projection has been demonstrated with violations of the Leggett-Garg inequality. Here we investigate the effects of weak measurement on a maximally entangled Bell state through application of the Hybrid Bell-Leggett-Garg inequality (BLGI) on a linear chain of four transmon qubits. By correlating the results of weak ancilla measurements with subsequent projective readout, we achieve a violation of the BLGI with 27 standard deviations of certainty. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.02707v2-abstract-full').style.display = 'none'; document.getElementById('1504.02707v2-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 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2015. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1503.04364">arXiv:1503.04364</a> <span> [<a href="https://arxiv.org/pdf/1503.04364">pdf</a>, <a href="https://arxiv.org/format/1503.04364">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> <p class="title is-5 mathjax"> Traveling wave parametric amplifier with Josephson junctions using minimal resonator phase matching </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=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Chaudhuri%2C+S">S. Chaudhuri</a>, <a href="/search/cond-mat?searchtype=author&query=Gao%2C+J">J. Gao</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="1503.04364v1-abstract-short" style="display: inline;"> Josephson parametric amplifiers have become a critical tool in superconducting device physics due to their high gain and quantum-limited noise. Traveling wave parametric amplifiers (TWPAs) promise similar noise performance while allowing for significant increases in both bandwidth and dynamic range. We present a TWPA device based on an LC-ladder transmission line of Josephson junctions and paralle… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.04364v1-abstract-full').style.display = 'inline'; document.getElementById('1503.04364v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1503.04364v1-abstract-full" style="display: none;"> Josephson parametric amplifiers have become a critical tool in superconducting device physics due to their high gain and quantum-limited noise. Traveling wave parametric amplifiers (TWPAs) promise similar noise performance while allowing for significant increases in both bandwidth and dynamic range. We present a TWPA device based on an LC-ladder transmission line of Josephson junctions and parallel plate capacitors using low-loss amorphous silicon dielectric. Crucially, we have inserted $位/4$ resonators at regular intervals along the transmission line in order to maintain the phase matching condition between pump, signal, and idler and increase gain. We achieve an average gain of 12\,dB across a 4\,GHz span, along with an average saturation power of -92\,dBm with noise approaching the quantum limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.04364v1-abstract-full').style.display = 'none'; document.getElementById('1503.04364v1-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 March, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2015. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1501.07703">arXiv:1501.07703</a> <span> [<a href="https://arxiv.org/pdf/1501.07703">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/10.1038/ncomms8654">10.1038/ncomms8654 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Digital quantum simulation of fermionic models with a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Lamata%2C+L">L. Lamata</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Garc%C3%ADa-%C3%81lvarez%2C+L">L. Garc铆a-脕lvarez</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Solano%2C+E">E. Solano</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="1501.07703v1-abstract-short" style="display: inline;"> Simulating quantum physics with a device which itself is quantum mechanical, a notion Richard Feynman originated, would be an unparallelled computational resource. However, the universal quantum simulation of fermionic systems is daunting due to their particle statistics, and Feynman left as an open question whether it could be done, because of the need for non-local control. Here, we implement fe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1501.07703v1-abstract-full').style.display = 'inline'; document.getElementById('1501.07703v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1501.07703v1-abstract-full" style="display: none;"> Simulating quantum physics with a device which itself is quantum mechanical, a notion Richard Feynman originated, would be an unparallelled computational resource. However, the universal quantum simulation of fermionic systems is daunting due to their particle statistics, and Feynman left as an open question whether it could be done, because of the need for non-local control. Here, we implement fermionic interactions with digital techniques in a superconducting circuit. Focusing on the Hubbard model, we perform time evolution with constant interactions as well as a dynamic phase transition with up to four fermionic modes encoded in four qubits. The implemented digital approach is universal and allows for the efficient simulation of fermions in arbitrary spatial dimensions. We use in excess of 300 single-qubit and two-qubit gates, and reach global fidelities which are limited by gate errors. This demonstration highlights the feasibility of the digital approach and opens a viable route towards analog-digital quantum simulation of interacting fermions and bosons in large-scale solid state systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1501.07703v1-abstract-full').style.display = 'none'; document.getElementById('1501.07703v1-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, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2015. </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: 5 pages, 5 figures. Supplementary: 7 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 6, 7654 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1411.7403">arXiv:1411.7403</a> <span> [<a href="https://arxiv.org/pdf/1411.7403">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="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/10.1038/nature14270">10.1038/nature14270 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> State preservation by repetitive error detection in a superconducting quantum circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</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="1411.7403v1-abstract-short" style="display: inline;"> Quantum computing becomes viable when a quantum state can be preserved from environmentally-induced error. If quantum bits (qubits) are sufficiently reliable, errors are sparse and quantum error correction (QEC) is capable of identifying and correcting them. Adding more qubits improves the preservation by guaranteeing increasingly larger clusters of errors will not cause logical failure - a key re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1411.7403v1-abstract-full').style.display = 'inline'; document.getElementById('1411.7403v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1411.7403v1-abstract-full" style="display: none;"> Quantum computing becomes viable when a quantum state can be preserved from environmentally-induced error. If quantum bits (qubits) are sufficiently reliable, errors are sparse and quantum error correction (QEC) is capable of identifying and correcting them. Adding more qubits improves the preservation by guaranteeing increasingly larger clusters of errors will not cause logical failure - a key requirement for large-scale systems. Using QEC to extend the qubit lifetime remains one of the outstanding experimental challenges in quantum computing. Here, we report the protection of classical states from environmental bit-flip errors and demonstrate the suppression of these errors with increasing system size. We use a linear array of nine qubits, which is a natural precursor of the two-dimensional surface code QEC scheme, and track errors as they occur by repeatedly performing projective quantum non-demolition (QND) parity measurements. Relative to a single physical qubit, we reduce the failure rate in retrieving an input state by a factor of 2.7 for five qubits and a factor of 8.5 for nine qubits after eight cycles. Additionally, we tomographically verify preservation of the non-classical Greenberger-Horne-Zeilinger (GHZ) state. The successful suppression of environmentally-induced errors strongly motivates further research into the many exciting challenges associated with building a large-scale superconducting quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1411.7403v1-abstract-full').style.display = 'none'; document.getElementById('1411.7403v1-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 November, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2014. </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 5 pages, 4 figures. Supplemental 25 pages, 31 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 519, 66芒聙聯69 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1411.2613">arXiv:1411.2613</a> <span> [<a href="https://arxiv.org/pdf/1411.2613">pdf</a>, <a href="https://arxiv.org/format/1411.2613">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.3.044009">10.1103/PhysRevApplied.3.044009 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Qubit metrology of ultralow phase noise using randomized benchmarking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</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="1411.2613v3-abstract-short" style="display: inline;"> A precise measurement of dephasing over a range of timescales is critical for improving quantum gates beyond the error correction threshold. We present a metrological tool, based on randomized benchmarking, capable of greatly increasing the precision of Ramsey and spin echo sequences by the repeated but incoherent addition of phase noise. We find our SQUID-based qubit is not limited by $1/f$ flux… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1411.2613v3-abstract-full').style.display = 'inline'; document.getElementById('1411.2613v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1411.2613v3-abstract-full" style="display: none;"> A precise measurement of dephasing over a range of timescales is critical for improving quantum gates beyond the error correction threshold. We present a metrological tool, based on randomized benchmarking, capable of greatly increasing the precision of Ramsey and spin echo sequences by the repeated but incoherent addition of phase noise. We find our SQUID-based qubit is not limited by $1/f$ flux noise at short timescales, but instead observe a telegraph noise mechanism that is not amenable to study with standard measurement techniques. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1411.2613v3-abstract-full').style.display = 'none'; document.getElementById('1411.2613v3-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> 16 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 November, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2014. </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, 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 3 (2015) 044009 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1410.5793">arXiv:1410.5793</a> <span> [<a href="https://arxiv.org/pdf/1410.5793">pdf</a>, <a href="https://arxiv.org/ps/1410.5793">ps</a>, <a href="https://arxiv.org/format/1410.5793">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> <p class="title is-5 mathjax"> UCSB final report for the CSQ program: Review of decoherence and materials physics for superconducting qubits </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=Megrant%2C+A">A. Megrant</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="1410.5793v1-abstract-short" style="display: inline;"> We review progress at UCSB on understanding the physics of decoherence in superconducting qubits. Although many decoherence mechanisms were studied and fixed in the last 5 years, the most important ones are two-level state defects in amorphous dielectrics, non-equilibrium quasiparticles generated from stray infrared light, and radiation to slotline modes. With improved design, the performance of i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.5793v1-abstract-full').style.display = 'inline'; document.getElementById('1410.5793v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1410.5793v1-abstract-full" style="display: none;"> We review progress at UCSB on understanding the physics of decoherence in superconducting qubits. Although many decoherence mechanisms were studied and fixed in the last 5 years, the most important ones are two-level state defects in amorphous dielectrics, non-equilibrium quasiparticles generated from stray infrared light, and radiation to slotline modes. With improved design, the performance of integrated circuit transmons using the Xmon design are now close to world record performance: these devices have the advantage of retaining coherence when scaled up to 9 qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.5793v1-abstract-full').style.display = 'none'; document.getElementById('1410.5793v1-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 October, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2014. </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, 1 figure</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1410.3458">arXiv:1410.3458</a> <span> [<a href="https://arxiv.org/pdf/1410.3458">pdf</a>, <a href="https://arxiv.org/ps/1410.3458">ps</a>, <a href="https://arxiv.org/format/1410.3458">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Classical Physics">physics.class-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="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Calculation of Coupling Capacitance in Planar Electrodes </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=Barends%2C+R">Rami Barends</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="1410.3458v1-abstract-short" style="display: inline;"> We show how capacitance can be calculated simply and efficiently for electrodes cut in a 2-dimensional ground plane. These results are in good agreement with exact formulas and numerical simulations. </span> <span class="abstract-full has-text-grey-dark mathjax" id="1410.3458v1-abstract-full" style="display: none;"> We show how capacitance can be calculated simply and efficiently for electrodes cut in a 2-dimensional ground plane. These results are in good agreement with exact formulas and numerical simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1410.3458v1-abstract-full').style.display = 'none'; document.getElementById('1410.3458v1-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 October, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2014. </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">5 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/1407.4769">arXiv:1407.4769</a> <span> [<a href="https://arxiv.org/pdf/1407.4769">pdf</a>, <a href="https://arxiv.org/format/1407.4769">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/10.1063/1.4893297">10.1063/1.4893297 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterization and reduction of microfabrication-induced decoherence in superconducting quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C+M">C. M. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</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="1407.4769v1-abstract-short" style="display: inline;"> Many superconducting qubits are highly sensitive to dielectric loss, making the fabrication of coherent quantum circuits challenging. To elucidate this issue, we characterize the interfaces and surfaces of superconducting coplanar waveguide resonators and study the associated microwave loss. We show that contamination induced by traditional qubit lift-off processing is particularly detrimental to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1407.4769v1-abstract-full').style.display = 'inline'; document.getElementById('1407.4769v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1407.4769v1-abstract-full" style="display: none;"> Many superconducting qubits are highly sensitive to dielectric loss, making the fabrication of coherent quantum circuits challenging. To elucidate this issue, we characterize the interfaces and surfaces of superconducting coplanar waveguide resonators and study the associated microwave loss. We show that contamination induced by traditional qubit lift-off processing is particularly detrimental to quality factors without proper substrate cleaning, while roughness plays at most a small role. Aggressive surface treatment is shown to damage the crystalline substrate and degrade resonator quality. We also introduce methods to characterize and remove ultra-thin resist residue, providing a way to quantify and minimize remnant sources of loss on device surfaces. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1407.4769v1-abstract-full').style.display = 'none'; document.getElementById('1407.4769v1-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 July, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 105, 062601 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1406.3364">arXiv:1406.3364</a> <span> [<a href="https://arxiv.org/pdf/1406.3364">pdf</a>, <a href="https://arxiv.org/format/1406.3364">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/PhysRevA.90.030303">10.1103/PhysRevA.90.030303 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Rolling quantum dice with a superconducting qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Veitia%2C+A">A. Veitia</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</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=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</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="1406.3364v1-abstract-short" style="display: inline;"> One of the key challenges in quantum information is coherently manipulating the quantum state. However, it is an outstanding question whether control can be realized with low error. Only gates from the Clifford group -- containing $蟺$, $蟺/2$, and Hadamard gates -- have been characterized with high accuracy. Here, we show how the Platonic solids enable implementing and characterizing larger gate se… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1406.3364v1-abstract-full').style.display = 'inline'; document.getElementById('1406.3364v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1406.3364v1-abstract-full" style="display: none;"> One of the key challenges in quantum information is coherently manipulating the quantum state. However, it is an outstanding question whether control can be realized with low error. Only gates from the Clifford group -- containing $蟺$, $蟺/2$, and Hadamard gates -- have been characterized with high accuracy. Here, we show how the Platonic solids enable implementing and characterizing larger gate sets. We find that all gates can be implemented with low error. The results fundamentally imply arbitrary manipulation of the quantum state can be realized with high precision, providing new practical possibilities for designing efficient quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1406.3364v1-abstract-full').style.display = 'none'; document.getElementById('1406.3364v1-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 June, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2014. </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, 4 figures, including supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 90, 030303(R) (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1405.1915">arXiv:1405.1915</a> <span> [<a href="https://arxiv.org/pdf/1405.1915">pdf</a>, <a href="https://arxiv.org/ps/1405.1915">ps</a>, <a href="https://arxiv.org/format/1405.1915">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> <p class="title is-5 mathjax"> Tunable coupler for superconducting Xmon qubits: Perturbative nonlinear model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Geller%2C+M+R">Michael R. Geller</a>, <a href="/search/cond-mat?searchtype=author&query=Donate%2C+E">Emmanuel Donate</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">Pedram Roushan</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="1405.1915v1-abstract-short" style="display: inline;"> We study a recently demonstrated design for a high-performance tunable coupler suitable for superconducting Xmon and planar transmon qubits [Y. Chen et al., arXiv:1402.7367]. The coupler circuit uses a single flux-biased Josephson junction and acts as a tunable current divider. We calculate the effective qubit-qubit interaction Hamiltonian by treating the nonlinearity of the qubit and coupler junc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1405.1915v1-abstract-full').style.display = 'inline'; document.getElementById('1405.1915v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1405.1915v1-abstract-full" style="display: none;"> We study a recently demonstrated design for a high-performance tunable coupler suitable for superconducting Xmon and planar transmon qubits [Y. Chen et al., arXiv:1402.7367]. The coupler circuit uses a single flux-biased Josephson junction and acts as a tunable current divider. We calculate the effective qubit-qubit interaction Hamiltonian by treating the nonlinearity of the qubit and coupler junctions perturbatively. We find that the qubit nonlinearity has two principal effects: The first is to suppress the magnitude of the transverse XX coupling from that obtained in the harmonic approximation by about 15%. The second is to induce a small diagonal ZZ coupling. The effects of the coupler junction nonlinearity are negligible in the parameter regime considered. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1405.1915v1-abstract-full').style.display = 'none'; document.getElementById('1405.1915v1-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 May, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A 92, 012320 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1403.6808">arXiv:1403.6808</a> <span> [<a href="https://arxiv.org/pdf/1403.6808">pdf</a>, <a href="https://arxiv.org/format/1403.6808">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/ncomms6184">10.1038/ncomms6184 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simulating weak localization using superconducting quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</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="1403.6808v1-abstract-short" style="display: inline;"> Understanding complex quantum matter presents a central challenge in condensed matter physics. The difficulty lies in the exponential scaling of the Hilbert space with the system size, making solutions intractable for both analytical and conventional numerical methods. As originally envisioned by Richard Feynman, this class of problems can be tackled using controllable quantum simulators. Despite… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.6808v1-abstract-full').style.display = 'inline'; document.getElementById('1403.6808v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1403.6808v1-abstract-full" style="display: none;"> Understanding complex quantum matter presents a central challenge in condensed matter physics. The difficulty lies in the exponential scaling of the Hilbert space with the system size, making solutions intractable for both analytical and conventional numerical methods. As originally envisioned by Richard Feynman, this class of problems can be tackled using controllable quantum simulators. Despite many efforts, building an quantum emulator capable of solving generic quantum problems remains an outstanding challenge, as this involves controlling a large number of quantum elements. Here, employing a multi-element superconducting quantum circuit and manipulating a single microwave photon, we demonstrate that we can simulate the weak localization phenomenon observed in mesoscopic systems. By engineering the control sequence in our emulator circuit, we are also able to reproduce the well-known temperature dependence of weak localization. Furthermore, we can use our circuit to continuously tune the level of disorder, a parameter that is not readily accessible in mesoscopic systems. By demonstrating a high level of control and complexity, our experiment shows the potential for superconducting quantum circuits to realize scalable quantum simulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.6808v1-abstract-full').style.display = 'none'; document.getElementById('1403.6808v1-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 March, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2014. </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, including supplement</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 5, 5184 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1403.0035">arXiv:1403.0035</a> <span> [<a href="https://arxiv.org/pdf/1403.0035">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.112.240504">10.1103/PhysRevLett.112.240504 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal quantum control using randomized benchmarking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Hoi%2C+I+-">I. -C. Hoi</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%60Malley%2C+P+J+J">P. J. J. O`Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C">C. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</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="1403.0035v1-abstract-short" style="display: inline;"> We present a method for optimizing quantum control in experimental systems, using a subset of randomized benchmarking measurements to rapidly infer error. This is demonstrated to improve single- and two-qubit gates, minimize gate bleedthrough, where a gate mechanism can cause errors on subsequent gates, and identify control crosstalk in superconducting qubits. This method is able to correct parame… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.0035v1-abstract-full').style.display = 'inline'; document.getElementById('1403.0035v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1403.0035v1-abstract-full" style="display: none;"> We present a method for optimizing quantum control in experimental systems, using a subset of randomized benchmarking measurements to rapidly infer error. This is demonstrated to improve single- and two-qubit gates, minimize gate bleedthrough, where a gate mechanism can cause errors on subsequent gates, and identify control crosstalk in superconducting qubits. This method is able to correct parameters to where control errors no longer dominate, and is suitable for automated and closed-loop optimization of experimental systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1403.0035v1-abstract-full').style.display = 'none'; document.getElementById('1403.0035v1-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 February, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2014. </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, 7 figures including supplementary</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 112, 240504 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1402.7367">arXiv:1402.7367</a> <span> [<a href="https://arxiv.org/pdf/1402.7367">pdf</a>, <a href="https://arxiv.org/format/1402.7367">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/10.1103/PhysRevLett.113.220502">10.1103/PhysRevLett.113.220502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Qubit architecture with high coherence and fast tunable coupling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Leung%2C+N">N. Leung</a>, <a href="/search/cond-mat?searchtype=author&query=Fang%2C+M">M. Fang</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Quintana%2C+C+M">C. M. Quintana</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Geller%2C+M+R">Michael R. Geller</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="1402.7367v1-abstract-short" style="display: inline;"> We introduce a superconducting qubit architecture that combines high-coherence qubits and tunable qubit-qubit coupling. With the ability to set the coupling to zero, we demonstrate that this architecture is protected from the frequency crowding problems that arise from fixed coupling. More importantly, the coupling can be tuned dynamically with nanosecond resolution, making this architecture a ver… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.7367v1-abstract-full').style.display = 'inline'; document.getElementById('1402.7367v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1402.7367v1-abstract-full" style="display: none;"> We introduce a superconducting qubit architecture that combines high-coherence qubits and tunable qubit-qubit coupling. With the ability to set the coupling to zero, we demonstrate that this architecture is protected from the frequency crowding problems that arise from fixed coupling. More importantly, the coupling can be tuned dynamically with nanosecond resolution, making this architecture a versatile platform with applications ranging from quantum logic gates to quantum simulation. We illustrate the advantages of dynamic coupling by implementing a novel adiabatic controlled-Z gate, at a speed approaching that of single-qubit gates. Integrating coherence and scalable control, our "gmon" architecture is a promising path towards large-scale quantum computation and simulation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.7367v1-abstract-full').style.display = 'none'; document.getElementById('1402.7367v1-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 February, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 113, 220502(2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1402.4848">arXiv:1402.4848</a> <span> [<a href="https://arxiv.org/pdf/1402.4848">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/10.1038/nature13171">10.1038/nature13171 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Veitia%2C+A">A. Veitia</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Fowler%2C+A+G">A. G. Fowler</a>, <a href="/search/cond-mat?searchtype=author&query=Campbell%2C+B">B. Campbell</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Z">Z. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Dunsworth%2C+A">A. Dunsworth</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%60Malley%2C+P">P. O`Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</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="1402.4848v1-abstract-short" style="display: inline;"> A quantum computer can solve hard problems - such as prime factoring, database searching, and quantum simulation - at the cost of needing to protect fragile quantum states from error. Quantum error correction provides this protection, by distributing a logical state among many physical qubits via quantum entanglement. Superconductivity is an appealing platform, as it allows for constructing large… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.4848v1-abstract-full').style.display = 'inline'; document.getElementById('1402.4848v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1402.4848v1-abstract-full" style="display: none;"> A quantum computer can solve hard problems - such as prime factoring, database searching, and quantum simulation - at the cost of needing to protect fragile quantum states from error. Quantum error correction provides this protection, by distributing a logical state among many physical qubits via quantum entanglement. Superconductivity is an appealing platform, as it allows for constructing large quantum circuits, and is compatible with microfabrication. For superconducting qubits the surface code is a natural choice for error correction, as it uses only nearest-neighbour coupling and rapidly-cycled entangling gates. The gate fidelity requirements are modest: The per-step fidelity threshold is only about 99%. Here, we demonstrate a universal set of logic gates in a superconducting multi-qubit processor, achieving an average single-qubit gate fidelity of 99.92% and a two-qubit gate fidelity up to 99.4%. This places Josephson quantum computing at the fault-tolerant threshold for surface code error correction. Our quantum processor is a first step towards the surface code, using five qubits arranged in a linear array with nearest-neighbour coupling. As a further demonstration, we construct a five-qubit Greenberger-Horne-Zeilinger (GHZ) state using the complete circuit and full set of gates. The results demonstrate that Josephson quantum computing is a high-fidelity technology, with a clear path to scaling up to large-scale, fault-tolerant quantum circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1402.4848v1-abstract-full').style.display = 'none'; document.getElementById('1402.4848v1-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 February, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2014. </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, 13 figures, including supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 508, 500-503 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1312.7579">arXiv:1312.7579</a> <span> [<a href="https://arxiv.org/pdf/1312.7579">pdf</a>, <a href="https://arxiv.org/format/1312.7579">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="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/10.1063/1.4871088">10.1063/1.4871088 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High Fidelity Qubit Readout with the Superconducting Low-Inductance Undulatory Galvanometer Microwave Amplifier </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Hover%2C+D">D. Hover</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+S">S. Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Thorbeck%2C+T">T. Thorbeck</a>, <a href="/search/cond-mat?searchtype=author&query=Ribeill%2C+G+J">G. J. Ribeill</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</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=McDermott%2C+R">R. McDermott</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="1312.7579v1-abstract-short" style="display: inline;"> We describe the high fidelity dispersive measurement of a superconducting qubit using a microwave amplifier based on the Superconducting Low-inductance Undulatory Galvanometer (SLUG). The SLUG preamplifier achieves gain of 19 dB and yields a signal-to-noise ratio improvement of 9 dB over a state-of-the-art HEMT amplifier. We demonstrate a separation fidelity of 99% at 700 ns compared to 59% with t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1312.7579v1-abstract-full').style.display = 'inline'; document.getElementById('1312.7579v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1312.7579v1-abstract-full" style="display: none;"> We describe the high fidelity dispersive measurement of a superconducting qubit using a microwave amplifier based on the Superconducting Low-inductance Undulatory Galvanometer (SLUG). The SLUG preamplifier achieves gain of 19 dB and yields a signal-to-noise ratio improvement of 9 dB over a state-of-the-art HEMT amplifier. We demonstrate a separation fidelity of 99% at 700 ns compared to 59% with the HEMT alone. The SLUG displays a large dynamic range, with an input saturation power corresponding to 700 photons in the readout cavity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1312.7579v1-abstract-full').style.display = 'none'; document.getElementById('1312.7579v1-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> 29 December, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2013. </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, 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/1311.1180">arXiv:1311.1180</a> <span> [<a href="https://arxiv.org/pdf/1311.1180">pdf</a>, <a href="https://arxiv.org/format/1311.1180">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.112.210501">10.1103/PhysRevLett.112.210501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Catching Shaped Microwave Photons with 99.4% Absorption Efficiency </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</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="1311.1180v2-abstract-short" style="display: inline;"> We demonstrate a high efficiency deterministic quantum receiver to convert flying qubits to logic qubits. We employ a superconducting resonator, which is driven with a shaped pulse through an adjustable coupler. For the ideal "time reversed" shape, we measure absorption and receiver fidelities at the single microwave photon level of, respectively, 99.41% and 97.4%. These fidelities are comparable… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1311.1180v2-abstract-full').style.display = 'inline'; document.getElementById('1311.1180v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1311.1180v2-abstract-full" style="display: none;"> We demonstrate a high efficiency deterministic quantum receiver to convert flying qubits to logic qubits. We employ a superconducting resonator, which is driven with a shaped pulse through an adjustable coupler. For the ideal "time reversed" shape, we measure absorption and receiver fidelities at the single microwave photon level of, respectively, 99.41% and 97.4%. These fidelities are comparable with gates and measurement and exceed the deterministic quantum communication and computation fault tolerant thresholds. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1311.1180v2-abstract-full').style.display = 'none'; document.getElementById('1311.1180v2-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> 16 November, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 November, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2013. </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 paper: 5 pages, 4 figures. Supplement: 11 pages, 12 figures. Revised abstract and introduction. Minor changes to Figure 1 and figure captions</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 112, 210501 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1309.0198">arXiv:1309.0198</a> <span> [<a href="https://arxiv.org/pdf/1309.0198">pdf</a>, <a href="https://arxiv.org/ps/1309.0198">ps</a>, <a href="https://arxiv.org/format/1309.0198">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/10.1038/ncomms4135">10.1038/ncomms4135 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Reducing intrinsic decoherence in a superconducting circuit by quantum error detection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhong%2C+Y+P">Y. P. Zhong</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+Z+L">Z. L. Wang</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=Cleland%2C+A+N">A. N. Cleland</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</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="1309.0198v1-abstract-short" style="display: inline;"> A fundamental challenge for quantum information processing is reducing the impact of environmentally-induced errors. Quantum error detection (QED) provides one approach to handling such errors, in which errors are rejected when they are detected. Here we demonstrate a QED protocol based on the idea of quantum un-collapsing, using this protocol to suppress energy relaxation due to the environment i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.0198v1-abstract-full').style.display = 'inline'; document.getElementById('1309.0198v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1309.0198v1-abstract-full" style="display: none;"> A fundamental challenge for quantum information processing is reducing the impact of environmentally-induced errors. Quantum error detection (QED) provides one approach to handling such errors, in which errors are rejected when they are detected. Here we demonstrate a QED protocol based on the idea of quantum un-collapsing, using this protocol to suppress energy relaxation due to the environment in a three-qubit superconducting circuit. We encode quantum information in a target qubit, and use the other two qubits to detect and reject errors caused by energy relaxation. This protocol improves the storage time of a quantum state by a factor of roughly three, at the cost of a reduced probability of success. This constitutes the first experimental demonstration of an algorithm-based improvement in the lifetime of a quantum state stored in a qubit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1309.0198v1-abstract-full').style.display = 'none'; document.getElementById('1309.0198v1-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 September, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2013. </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, 5 figures, and 1 table including Supplementary Information</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 5, 3135 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1306.3718">arXiv:1306.3718</a> <span> [<a href="https://arxiv.org/pdf/1306.3718">pdf</a>, <a href="https://arxiv.org/format/1306.3718">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> </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/10.1063/1.4818710">10.1063/1.4818710 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fluctuations From Edge Defects in Superconducting Resonators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J+Y">J. Y. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</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=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</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="1306.3718v1-abstract-short" style="display: inline;"> Superconducting resonators, used in astronomy and quantum computation, couple strongly to microscopic two-level defects. We monitor the microwave response of superconducting resonators and observe fluctuations in dissipation and resonance frequency. We present a unified model where the observed dissipative and dispersive effects can be explained as originating from a bath of fluctuating two-level… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1306.3718v1-abstract-full').style.display = 'inline'; document.getElementById('1306.3718v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1306.3718v1-abstract-full" style="display: none;"> Superconducting resonators, used in astronomy and quantum computation, couple strongly to microscopic two-level defects. We monitor the microwave response of superconducting resonators and observe fluctuations in dissipation and resonance frequency. We present a unified model where the observed dissipative and dispersive effects can be explained as originating from a bath of fluctuating two-level systems. From these measurements, we quantify the number and distribution of the defects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1306.3718v1-abstract-full').style.display = 'none'; document.getElementById('1306.3718v1-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> 16 June, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2013. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 103, 072601 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1306.2966">arXiv:1306.2966</a> <span> [<a href="https://arxiv.org/pdf/1306.2966">pdf</a>, <a href="https://arxiv.org/format/1306.2966">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> <p class="title is-5 mathjax"> Sputtered TiN films for superconducting coplanar waveguide resonators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Ohya%2C+S">Shinobu Ohya</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">Ben Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">Anthony Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">Charles Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">Rami Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Low%2C+D">David Low</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">Josh Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P">Peter O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">Pedram Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">Amit Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">James Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">Theodore C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Schultz%2C+B+D">B. D. Schultz</a>, <a href="/search/cond-mat?searchtype=author&query=Palmstr%C3%B8m%2C+C+J">Chris J Palmstr酶m</a>, <a href="/search/cond-mat?searchtype=author&query=Mazin%2C+B+A">Benjamin A. Mazin</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">Andrew 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="1306.2966v1-abstract-short" style="display: inline;"> We present a systematic study of the properties of TiN films by varying the deposition conditions in an ultra-high-vacuum reactive magnetron sputtering chamber. By increasing the deposition pressure from 2 to 9 mTorr while keeping a nearly stoichiometric composition of Ti(1-x)N(x) (x=0.5), the film resistivity increases, the dominant crystal orientation changes from (100) to (111), grain boundarie… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1306.2966v1-abstract-full').style.display = 'inline'; document.getElementById('1306.2966v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1306.2966v1-abstract-full" style="display: none;"> We present a systematic study of the properties of TiN films by varying the deposition conditions in an ultra-high-vacuum reactive magnetron sputtering chamber. By increasing the deposition pressure from 2 to 9 mTorr while keeping a nearly stoichiometric composition of Ti(1-x)N(x) (x=0.5), the film resistivity increases, the dominant crystal orientation changes from (100) to (111), grain boundaries become clearer, and the strong compressive strain changes to weak tensile strain. The TiN films absorb a high concentration of contaminants including hydrogen, carbon, and oxygen when they are exposed to air after deposition. With the target-substrate distance set to 88 mm the contaminant levels increase from ~0.1% to ~10% as the pressure is increased from 2 to 9 mTorr. The contaminant concentrations also correlate with in-plane distance from the center of the substrate and increase by roughly two orders of magnitude as the target-substrate distance is increased from 88 mm to 266 mm. These contaminants are found to strongly influence the properties of TiN films. For instance, the resistivity of stoichiometric films increases by around a factor of 5 as the oxygen content increases from 0.1% to 11%. These results suggest that the sputtered TiN particle energy is critical in determining the TiN film properties, and that it is important to control this energy to obtain high-quality TiN films. Superconducting coplanar waveguide resonators made from a series of nearly stoichiometric films grown at pressures from 2 mTorr to 7 mTorr show an increase in intrinsic quality factor from ~10^4 to ~10^6 as the magnitude of the compressive strain decreases from nearly 3800 MPa to approximately 150 MPa and the oxygen content increases from 0.1% to 8%. The films with a higher oxygen content exhibit lower loss, but the nonuniformity of the oxygen incorporation hinders the use of sputtered TiN in larger circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1306.2966v1-abstract-full').style.display = 'none'; document.getElementById('1306.2966v1-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, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2013. </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, 9 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/1304.2322">arXiv:1304.2322</a> <span> [<a href="https://arxiv.org/pdf/1304.2322">pdf</a>, <a href="https://arxiv.org/ps/1304.2322">ps</a>, <a href="https://arxiv.org/format/1304.2322">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/PhysRevLett.111.080502">10.1103/PhysRevLett.111.080502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coherent Josephson qubit suitable for scalable quantum integrated circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Jeffrey%2C+E">E. Jeffrey</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Mutus%2C+J">J. Mutus</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P">P. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Roushan%2C+P">P. Roushan</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</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="1304.2322v1-abstract-short" style="display: inline;"> We demonstrate a planar, tunable superconducting qubit with energy relaxation times up to 44 microseconds. This is achieved by using a geometry designed to both minimize radiative loss and reduce coupling to materials-related defects. At these levels of coherence, we find a fine structure in the qubit energy lifetime as a function of frequency, indicating the presence of a sparse population of inc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.2322v1-abstract-full').style.display = 'inline'; document.getElementById('1304.2322v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1304.2322v1-abstract-full" style="display: none;"> We demonstrate a planar, tunable superconducting qubit with energy relaxation times up to 44 microseconds. This is achieved by using a geometry designed to both minimize radiative loss and reduce coupling to materials-related defects. At these levels of coherence, we find a fine structure in the qubit energy lifetime as a function of frequency, indicating the presence of a sparse population of incoherent, weakly coupled two-level defects. This is supported by a model analysis as well as experimental variations in the geometry. Our `Xmon' qubit combines facile fabrication, straightforward connectivity, fast control, and long coherence, opening a viable route to constructing a chip-based quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1304.2322v1-abstract-full').style.display = 'none'; document.getElementById('1304.2322v1-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 April, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2013. </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, 9 figures, including supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 111, 080502 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1301.1719">arXiv:1301.1719</a> <span> [<a href="https://arxiv.org/pdf/1301.1719">pdf</a>, <a href="https://arxiv.org/ps/1301.1719">ps</a>, <a href="https://arxiv.org/format/1301.1719">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/PhysRevA.87.022309">10.1103/PhysRevA.87.022309 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-fidelity CZ gate for resonator-based superconducting quantum computers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Ghosh%2C+J">Joydip Ghosh</a>, <a href="/search/cond-mat?searchtype=author&query=Galiautdinov%2C+A">Andrei Galiautdinov</a>, <a href="/search/cond-mat?searchtype=author&query=Zhou%2C+Z">Zhongyuan Zhou</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</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=Geller%2C+M+R">Michael R. Geller</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="1301.1719v1-abstract-short" style="display: inline;"> A possible building block for a scalable quantum computer has recently been demonstrated [M. Mariantoni et al., Science 334, 61 (2011)]. This architecture consists of superconducting qubits capacitively coupled both to individual memory resonators as well as a common bus. In this work we study a natural primitive entangling gate for this and related resonator-based architectures, which consists of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1301.1719v1-abstract-full').style.display = 'inline'; document.getElementById('1301.1719v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1301.1719v1-abstract-full" style="display: none;"> A possible building block for a scalable quantum computer has recently been demonstrated [M. Mariantoni et al., Science 334, 61 (2011)]. This architecture consists of superconducting qubits capacitively coupled both to individual memory resonators as well as a common bus. In this work we study a natural primitive entangling gate for this and related resonator-based architectures, which consists of a CZ operation between a qubit and the bus. The CZ gate is implemented with the aid of the non-computational qubit |2> state [F. W. Strauch et al., Phys. Rev. Lett. 91, 167005 (2003)]. Assuming phase or transmon qubits with 300 MHz anharmonicity, we show that by using only low frequency qubit-bias control it is possible to implement the qubit-bus CZ gate with 99.9% (99.99%) fidelity in about 17ns (23ns) with a realistic two-parameter pulse profile, plus two auxiliary z rotations. The fidelity measure we refer to here is a state-averaged intrinsic process fidelity, which does not include any effects of noise or decoherence. These results apply to a multi-qubit device that includes strongly coupled memory resonators. We investigate the performance of the qubit-bus CZ gate as a function of qubit anharmonicity, indentify the dominant intrinsic error mechanism and derive an associated fidelity estimator, quantify the pulse shape sensitivity and precision requirements, simulate qubit-qubit CZ gates that are mediated by the bus resonator, and also attempt a global optimization of system parameters including resonator frequencies and couplings. Our results are relevant for a wide range of superconducting hardware designs that incorporate resonators and suggest that it should be possible to demonstrate a 99.9% CZ gate with existing transmon qubits, which would constitute an important step towards the development of an error-corrected superconducting quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1301.1719v1-abstract-full').style.display = 'none'; document.getElementById('1301.1719v1-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 January, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2013. </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">22 pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A 87, 022309 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1210.5260">arXiv:1210.5260</a> <span>  </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> <p class="title is-5 mathjax"> Universal quantum simulation with pre-threshold superconducting qubits: Single-excitation subspace method </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Geller%2C+M+R">Michael R. Geller</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=Sornborger%2C+A+T">Andrew T. Sornborger</a>, <a href="/search/cond-mat?searchtype=author&query=Stancil%2C+P+C">Phillip C. Stancil</a>, <a href="/search/cond-mat?searchtype=author&query=Pritchett%2C+E+J">Emily J. Pritchett</a>, <a href="/search/cond-mat?searchtype=author&query=Galiautdinov%2C+A">Andrei Galiautdinov</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="1210.5260v2-abstract-short" style="display: inline;"> We propose a method for general-purpose quantum computation and simulation that is well suited for today's pre-threshold-fidelity superconducting qubits. This approach makes use of the $n$-dimensional single-excitation subspace (SES) of a system of $n$ tunably coupled qubits. It can be viewed as a nonscalable special case of the standard gate-based quantum computing model, but allows many operatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1210.5260v2-abstract-full').style.display = 'inline'; document.getElementById('1210.5260v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1210.5260v2-abstract-full" style="display: none;"> We propose a method for general-purpose quantum computation and simulation that is well suited for today's pre-threshold-fidelity superconducting qubits. This approach makes use of the $n$-dimensional single-excitation subspace (SES) of a system of $n$ tunably coupled qubits. It can be viewed as a nonscalable special case of the standard gate-based quantum computing model, but allows many operations in the unitary group SU($n$) to be implemented by a single application of the Hamiltonian. Our approach bypasses the need to decompose the evolution operator into elementary gates, making large, nontrivial computations possible without error correction. The method is especially well suited for universal quantum simulation, specifically simulation of the Schr枚dinger equation with a real but otherwise arbitrary $n \times n$ Hamiltonian. We argue that a 1000-qubit SES processor, which would require no known improvements in superconducting device technology and which could be built today, should be capable of achieving quantum speedup relative to a petaflop supercomputer. We speculate on the utility and practicality of such a universal quantum simulator. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1210.5260v2-abstract-full').style.display = 'none'; document.getElementById('1210.5260v2-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 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2012. </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">Superseded by arXiv:1505.04990</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1209.1781">arXiv:1209.1781</a> <span> [<a href="https://arxiv.org/pdf/1209.1781">pdf</a>, <a href="https://arxiv.org/ps/1209.1781">ps</a>, <a href="https://arxiv.org/format/1209.1781">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/10.1063/1.4764940">10.1063/1.4764940 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiplexed dispersive readout of superconducting phase qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P">P. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T">T. White</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">M. Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</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="1209.1781v1-abstract-short" style="display: inline;"> We introduce a frequency-multiplexed readout scheme for superconducting phase qubits. Using a quantum circuit with four phase qubits, we couple each qubit to a separate lumped-element superconducting readout resonator, with the readout resonators connected in parallel to a single measurement line. The readout resonators and control electronics are designed so that all four qubits can be read out s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1209.1781v1-abstract-full').style.display = 'inline'; document.getElementById('1209.1781v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1209.1781v1-abstract-full" style="display: none;"> We introduce a frequency-multiplexed readout scheme for superconducting phase qubits. Using a quantum circuit with four phase qubits, we couple each qubit to a separate lumped-element superconducting readout resonator, with the readout resonators connected in parallel to a single measurement line. The readout resonators and control electronics are designed so that all four qubits can be read out simultaneously using frequency multiplexing on the one measurement line. This technology provides a highly efficient and compact means for reading out multiple qubits, a significant advantage for scaling up to larger numbers of qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1209.1781v1-abstract-full').style.display = 'none'; document.getElementById('1209.1781v1-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 September, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2012. </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/1209.1674">arXiv:1209.1674</a> <span> [<a href="https://arxiv.org/pdf/1209.1674">pdf</a>, <a href="https://arxiv.org/ps/1209.1674">ps</a>, <a href="https://arxiv.org/format/1209.1674">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/10.1103/PhysRevLett.110.150502">10.1103/PhysRevLett.110.150502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Excitation of superconducting qubits from hot non-equilibrium quasiparticles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lenander%2C+M">M. Lenander</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</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="1209.1674v2-abstract-short" style="display: inline;"> Superconducting qubits probe environmental defects such as non-equilibrium quasiparticles, an important source of decoherence. We show that "hot" non-equilibrium quasiparticles, with energies above the superconducting gap, affect qubits differently from quasiparticles at the gap, implying qubits can probe the dynamic quasiparticle energy distribution. For hot quasiparticles, we predict a non-nelig… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1209.1674v2-abstract-full').style.display = 'inline'; document.getElementById('1209.1674v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1209.1674v2-abstract-full" style="display: none;"> Superconducting qubits probe environmental defects such as non-equilibrium quasiparticles, an important source of decoherence. We show that "hot" non-equilibrium quasiparticles, with energies above the superconducting gap, affect qubits differently from quasiparticles at the gap, implying qubits can probe the dynamic quasiparticle energy distribution. For hot quasiparticles, we predict a non-neligable increase in the qubit excited state probability P_e. By injecting hot quasiparticles into a qubit, we experimentally measure an increase of P_e in semi-quantitative agreement with the model and rule out the typically assumed thermal distribution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1209.1674v2-abstract-full').style.display = 'none'; document.getElementById('1209.1674v2-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, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 September, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2012. </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 paper: 5 pages, 5 figures. Supplement: 1 page, 1 figure, 1 table. Updated to user-prepared accepted version. Key changes: Supplement added, Introduction rewritten, Figs.2,3,5 revised, Fig.4 added</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 110, 150502 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1208.2950">arXiv:1208.2950</a> <span> [<a href="https://arxiv.org/pdf/1208.2950">pdf</a>, <a href="https://arxiv.org/format/1208.2950">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.110.107001">10.1103/PhysRevLett.110.107001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Controlled catch and release of microwave photon states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">Alexander N. Korotkov</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="1208.2950v1-abstract-short" style="display: inline;"> The quantum behavior of superconducting qubits coupled to resonators is very similar to that of atoms in optical cavities [1, 2], in which the resonant cavity confines photons and promotes strong light-matter interactions. The cavity end-mirrors determine the performance of the coupled system, with higher mirror reflectivity yielding better quantum coherence, but higher mirror transparency giving… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1208.2950v1-abstract-full').style.display = 'inline'; document.getElementById('1208.2950v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1208.2950v1-abstract-full" style="display: none;"> The quantum behavior of superconducting qubits coupled to resonators is very similar to that of atoms in optical cavities [1, 2], in which the resonant cavity confines photons and promotes strong light-matter interactions. The cavity end-mirrors determine the performance of the coupled system, with higher mirror reflectivity yielding better quantum coherence, but higher mirror transparency giving improved measurement and control, forcing a compromise. An alternative is to control the mirror transparency, enabling switching between long photon lifetime during quantum interactions and large signal strength when performing measurements. Here we demonstrate the superconducting analogue, using a quantum system comprising a resonator and a qubit, with variable coupling to a measurement transmission line. The coupling can be adjusted through zero to a photon emission rate 1,000 times the intrinsic photon decay rate. We use this system to control photons in coherent states as well as in non-classical Fock states, and dynamically shape the waveform of released photons. This has direct applications to circuit quantum electrodynamics [3], and may enable high-fidelity quantum state transfer between distant qubits, for which precisely-controlled waveform shaping is a critical and non-trivial requirement [4, 5]. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1208.2950v1-abstract-full').style.display = 'none'; document.getElementById('1208.2950v1-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 August, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2012. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1208.2441">arXiv:1208.2441</a> <span> [<a href="https://arxiv.org/pdf/1208.2441">pdf</a>, <a href="https://arxiv.org/ps/1208.2441">ps</a>, <a href="https://arxiv.org/format/1208.2441">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.110.100404">10.1103/PhysRevLett.110.100404 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Direct Wigner tomography of a superconducting anharmonic oscillator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Shalibo%2C+Y">Yoni Shalibo</a>, <a href="/search/cond-mat?searchtype=author&query=Resh%2C+R">Roy Resh</a>, <a href="/search/cond-mat?searchtype=author&query=Fogel%2C+O">Ofer Fogel</a>, <a href="/search/cond-mat?searchtype=author&query=Shwa%2C+D">David Shwa</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczak%2C+R">Radoslaw Bialczak</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=Katz%2C+N">Nadav Katz</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="1208.2441v1-abstract-short" style="display: inline;"> The analysis of wave-packet dynamics may be greatly simplified when viewed in phase-space. While harmonic oscillators are often used as a convenient platform to study wave-packets, arbitrary state preparation in these systems is more challenging. Here, we demonstrate a direct measurement of the Wigner distribution of complex photon states in an anharmonic oscillator - a superconducting phase circu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1208.2441v1-abstract-full').style.display = 'inline'; document.getElementById('1208.2441v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1208.2441v1-abstract-full" style="display: none;"> The analysis of wave-packet dynamics may be greatly simplified when viewed in phase-space. While harmonic oscillators are often used as a convenient platform to study wave-packets, arbitrary state preparation in these systems is more challenging. Here, we demonstrate a direct measurement of the Wigner distribution of complex photon states in an anharmonic oscillator - a superconducting phase circuit, biased in the small anharmonicity regime. We test our method on both non-classical states composed of two energy eigenstates and on the dynamics of a phase-locked wavepacket. This method requires a simple calibration, and is easily applicable in our system out to the fifth level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1208.2441v1-abstract-full').style.display = 'none'; document.getElementById('1208.2441v1-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 August, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2012. </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">5 figures, 1 table and supplementary material</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1202.5707">arXiv:1202.5707</a> <span> [<a href="https://arxiv.org/pdf/1202.5707">pdf</a>, <a href="https://arxiv.org/format/1202.5707">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/10.1038/nphys2385">10.1038/nphys2385 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Computing prime factors with a Josephson phase qubit quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">Rami Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">Julian Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">Anthony Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P">Peter O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">Amit Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">James Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T">Ted White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Cleland%2C+A+N">Andrew 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="1202.5707v1-abstract-short" style="display: inline;"> A quantum processor (QuP) can be used to exploit quantum mechanics to find the prime factors of composite numbers[1]. Compiled versions of Shor's algorithm have been demonstrated on ensemble quantum systems[2] and photonic systems[3-5], however this has yet to be shown using solid state quantum bits (qubits). Two advantages of superconducting qubit architectures are the use of conventional microfa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1202.5707v1-abstract-full').style.display = 'inline'; document.getElementById('1202.5707v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1202.5707v1-abstract-full" style="display: none;"> A quantum processor (QuP) can be used to exploit quantum mechanics to find the prime factors of composite numbers[1]. Compiled versions of Shor's algorithm have been demonstrated on ensemble quantum systems[2] and photonic systems[3-5], however this has yet to be shown using solid state quantum bits (qubits). Two advantages of superconducting qubit architectures are the use of conventional microfabrication techniques, which allow straightforward scaling to large numbers of qubits, and a toolkit of circuit elements that can be used to engineer a variety of qubit types and interactions[6, 7]. Using a number of recent qubit control and hardware advances [7-13], here we demonstrate a nine-quantum-element solid-state QuP and show three experiments to highlight its capabilities. We begin by characterizing the device with spectroscopy. Next, we produces coherent interactions between five qubits and verify bi- and tripartite entanglement via quantum state tomography (QST) [8, 12, 14, 15]. In the final experiment, we run a three-qubit compiled version of Shor's algorithm to factor the number 15, and successfully find the prime factors 48% of the time. Improvements in the superconducting qubit coherence times and more complex circuits should provide the resources necessary to factor larger composite numbers and run more intricate quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1202.5707v1-abstract-full').style.display = 'none'; document.getElementById('1202.5707v1-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 February, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2012. </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">5 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/1201.3384">arXiv:1201.3384</a> <span> [<a href="https://arxiv.org/pdf/1201.3384">pdf</a>, <a href="https://arxiv.org/ps/1201.3384">ps</a>, <a href="https://arxiv.org/format/1201.3384">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="Materials Science">cond-mat.mtrl-sci</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/10.1063/1.3693409">10.1063/1.3693409 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Planar Superconducting Resonators with Internal Quality Factors above One Million </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=Neill%2C+C">C. Neill</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chiaro%2C+B">B. Chiaro</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Feigl%2C+L">L. Feigl</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Palmstr%C3%B8m%2C+C+J">C. J. Palmstr酶m</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=Cleland%2C+A+N">A. N. Cleland</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="1201.3384v1-abstract-short" style="display: inline;"> We describe the fabrication and measurement of microwave coplanar waveguide resonators with internal quality factors above 10 million at high microwave powers and over 1 million at low powers, with the best low power results approaching 2 million, corresponding to ~1 photon in the resonator. These quality factors are achieved by controllably producing very smooth and clean interfaces between the r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1201.3384v1-abstract-full').style.display = 'inline'; document.getElementById('1201.3384v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1201.3384v1-abstract-full" style="display: none;"> We describe the fabrication and measurement of microwave coplanar waveguide resonators with internal quality factors above 10 million at high microwave powers and over 1 million at low powers, with the best low power results approaching 2 million, corresponding to ~1 photon in the resonator. These quality factors are achieved by controllably producing very smooth and clean interfaces between the resonators' aluminum metallization and the underlying single crystal sapphire substrate. Additionally, we describe a method for analyzing the resonator microwave response, with which we can directly determine the internal quality factor and frequency of a resonator embedded in an imperfect measurement circuit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1201.3384v1-abstract-full').style.display = 'none'; document.getElementById('1201.3384v1-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> 16 January, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2012. </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, 1 table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1112.2458">arXiv:1112.2458</a> <span> [<a href="https://arxiv.org/pdf/1112.2458">pdf</a>, <a href="https://arxiv.org/ps/1112.2458">ps</a>, <a href="https://arxiv.org/format/1112.2458">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.110.107001">10.1103/PhysRevLett.110.107001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dynamic quantum Kerr effect in circuit quantum electrodynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">M. Mariantoni</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=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</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=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=Zhao%2C+J">J. Zhao</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="1112.2458v1-abstract-short" style="display: inline;"> A superconducting qubit coupled to a microwave resonator provides a controllable system that enables fundamental studies of light-matter interactions. In the dispersive regime, photons in the resonator exhibit induced frequency and phase shifts which are revealed in the resonator transmission spectrum measured with fixed qubit-resonator detuning. In this static detuning scheme, the phase shift is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1112.2458v1-abstract-full').style.display = 'inline'; document.getElementById('1112.2458v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1112.2458v1-abstract-full" style="display: none;"> A superconducting qubit coupled to a microwave resonator provides a controllable system that enables fundamental studies of light-matter interactions. In the dispersive regime, photons in the resonator exhibit induced frequency and phase shifts which are revealed in the resonator transmission spectrum measured with fixed qubit-resonator detuning. In this static detuning scheme, the phase shift is measured in the far-detuned, linear dispersion regime to avoid measurement-induced demolition of the qubit quantum state. Here we explore the qubit-resonator dispersive interaction over a much broader range of detunings, by using a dynamic procedure where the qubit transition is driven adiabatically. We use resonator Wigner tomography to monitor the interaction, revealing exotic non-linear effects on different photon states, e.g., Fock states, coherent states, and Schrodinger cat states, thereby demonstrating a quantum Kerr effect in the dynamic framework. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1112.2458v1-abstract-full').style.display = 'none'; document.getElementById('1112.2458v1-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 December, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2011. </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, 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/1111.2890">arXiv:1111.2890</a> <span> [<a href="https://arxiv.org/pdf/1111.2890">pdf</a>, <a href="https://arxiv.org/ps/1111.2890">ps</a>, <a href="https://arxiv.org/format/1111.2890">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> </div> </div> <p class="title is-5 mathjax"> Surface spin fluctuations probed with flux noise and coherence in Josephson phase qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">Daniel Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</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=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</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=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Vaisencher%2C+A">A. Vaisencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yamamoto%2C+T">T. Yamamoto</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Yi Yin</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="1111.2890v1-abstract-short" style="display: inline;"> We measure the dependence of qubit phase coherence and surface spin induced flux noise on inductor loop geometry. While wider inductor traces change neither the flux noise power spectrum nor the qubit dephasing time, increased inductance leads to a simultaneous increase in both. Using our protocol for measuring low frequency flux noise, we make a direct comparison between the flux noise spectrum a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1111.2890v1-abstract-full').style.display = 'inline'; document.getElementById('1111.2890v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1111.2890v1-abstract-full" style="display: none;"> We measure the dependence of qubit phase coherence and surface spin induced flux noise on inductor loop geometry. While wider inductor traces change neither the flux noise power spectrum nor the qubit dephasing time, increased inductance leads to a simultaneous increase in both. Using our protocol for measuring low frequency flux noise, we make a direct comparison between the flux noise spectrum and qubit phase decay, finding agreement within 10% of theory. The dependence of the measured flux noise on inductor geometry is consistent with a noise source correlation length between 6 and 400 um. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1111.2890v1-abstract-full').style.display = 'none'; document.getElementById('1111.2890v1-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 November, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1109.3743">arXiv:1109.3743</a> <span> [<a href="https://arxiv.org/pdf/1109.3743">pdf</a>, <a href="https://arxiv.org/format/1109.3743">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="Atomic Physics">physics.atom-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/10.1126/science.1208517">10.1126/science.1208517 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Implementing the Quantum von Neumann Architecture with Superconducting Circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Yamamoto%2C+T">T. Yamamoto</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</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=Chen%2C+Y">Y. Chen</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=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=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Korotkov%2C+A+N">A. N. Korotkov</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="1109.3743v1-abstract-short" style="display: inline;"> The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1109.3743v1-abstract-full').style.display = 'inline'; document.getElementById('1109.3743v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1109.3743v1-abstract-full" style="display: none;"> The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two superconducting qubits coupled through a quantum bus, two quantum memories, and two zeroing registers. Two vital algorithms for quantum computing are demonstrated, the quantum Fourier transform, with 66% process fidelity, and the three-qubit Toffoli OR phase gate, with 98% phase fidelity. Our results, in combination especially with longer qubit coherence, illustrate a potentially viable approach to factoring numbers and implementing simple quantum error correction codes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1109.3743v1-abstract-full').style.display = 'none'; document.getElementById('1109.3743v1-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> 16 September, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2011. </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">To be published in Science (submitted version); 9 pages+4 figs. (main), 34 pages+12 figs.+3 tables (supplementary); includes Toffoli gate+quantum Fourier transform</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 334, 61-65 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1107.5526">arXiv:1107.5526</a> <span> [<a href="https://arxiv.org/pdf/1107.5526">pdf</a>, <a href="https://arxiv.org/ps/1107.5526">ps</a>, <a href="https://arxiv.org/format/1107.5526">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.108.037701">10.1103/PhysRevLett.108.037701 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum and Classical Chirps in an Anharmonic Oscillator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Shalibo%2C+Y">Yoni Shalibo</a>, <a href="/search/cond-mat?searchtype=author&query=Rofe%2C+Y">Ya'ara Rofe</a>, <a href="/search/cond-mat?searchtype=author&query=Barth%2C+I">Ido Barth</a>, <a href="/search/cond-mat?searchtype=author&query=Friedland%2C+L">Lazar Friedland</a>, <a href="/search/cond-mat?searchtype=author&query=Bialczack%2C+R">Radoslaw Bialczack</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=Katz%2C+N">Nadav Katz</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="1107.5526v2-abstract-short" style="display: inline;"> We measure the state dynamics of a tunable anharmonic quantum system, the Josephson phase circuit, under the excitation of a frequency-chirped drive. At small anharmonicity, the state evolves like a wavepacket - a characteristic response in classical oscillators; in this regime we report exponentially enhanced lifetimes of highly excited states, held by the drive. At large anharmonicity, we observ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1107.5526v2-abstract-full').style.display = 'inline'; document.getElementById('1107.5526v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1107.5526v2-abstract-full" style="display: none;"> We measure the state dynamics of a tunable anharmonic quantum system, the Josephson phase circuit, under the excitation of a frequency-chirped drive. At small anharmonicity, the state evolves like a wavepacket - a characteristic response in classical oscillators; in this regime we report exponentially enhanced lifetimes of highly excited states, held by the drive. At large anharmonicity, we observe sharp steps, corresponding to the excitation of discrete energy levels. The continuous transition between the two regimes is mapped by measuring the threshold of these two effects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1107.5526v2-abstract-full').style.display = 'none'; document.getElementById('1107.5526v2-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 December, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 July, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2011. </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 material</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1107.4698">arXiv:1107.4698</a> <span> [<a href="https://arxiv.org/pdf/1107.4698">pdf</a>, <a href="https://arxiv.org/ps/1107.4698">ps</a>, <a href="https://arxiv.org/format/1107.4698">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> </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/10.1063/1.3637047">10.1063/1.3637047 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Surface loss simulations of superconducting coplanar waveguide resonators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</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=Chen%2C+Y">Yu Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">Erik Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Megrant%2C+A">A. Megrant</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P+J+J">P. J. J. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Sank%2C+D">D. Sank</a>, <a href="/search/cond-mat?searchtype=author&query=Vainsencher%2C+A">A. Vainsencher</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</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="1107.4698v1-abstract-short" style="display: inline;"> Losses in superconducting planar resonators are presently assumed to predominantly arise from surface-oxide dissipation, due to experimental losses varying with choice of materials. We model and simulate the magnitude of the loss from interface surfaces in the resonator, and investigate the dependence on power, resonator geometry, and dimensions. Surprisingly, the dominant surface loss is found to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1107.4698v1-abstract-full').style.display = 'inline'; document.getElementById('1107.4698v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1107.4698v1-abstract-full" style="display: none;"> Losses in superconducting planar resonators are presently assumed to predominantly arise from surface-oxide dissipation, due to experimental losses varying with choice of materials. We model and simulate the magnitude of the loss from interface surfaces in the resonator, and investigate the dependence on power, resonator geometry, and dimensions. Surprisingly, the dominant surface loss is found to arise from the metal-substrate and substrate-air interfaces. This result will be useful in guiding device optimization, even with conventional materials. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1107.4698v1-abstract-full').style.display = 'none'; document.getElementById('1107.4698v1-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> 23 July, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2011. </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 paper: 4 pages, 4 figures, 1 table. Supplementary material: 4 pages, 2 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 99, 113513 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1105.4642">arXiv:1105.4642</a> <span> [<a href="https://arxiv.org/pdf/1105.4642">pdf</a>, <a href="https://arxiv.org/ps/1105.4642">ps</a>, <a href="https://arxiv.org/format/1105.4642">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/10.1063/1.3638063">10.1063/1.3638063 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Loss and decoherence due to stray infrared light in superconducting quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barends%2C+R">R. Barends</a>, <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Lenander%2C+M">M. Lenander</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</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=Kelly%2C+J">J. Kelly</a>, <a href="/search/cond-mat?searchtype=author&query=Lucero%2C+E">E. Lucero</a>, <a href="/search/cond-mat?searchtype=author&query=O%27Malley%2C+P">P. O'Malley</a>, <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">M. Mariantoni</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=White%2C+T+C">T. C. White</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</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=Baselmans%2C+J+J+A">J. J. A. Baselmans</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="1105.4642v1-abstract-short" style="display: inline;"> We find that stray infrared light from the 4 K stage in a cryostat can cause significant loss in superconducting resonators and qubits. For devices shielded in only a metal box, we measured resonators with quality factors Q = 10^5 and qubits with energy relaxation times T_1=120 ns, consistent with a stray light-induced quasiparticle density of 170-230 渭m^{-3}. By adding a second black shield at th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1105.4642v1-abstract-full').style.display = 'inline'; document.getElementById('1105.4642v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1105.4642v1-abstract-full" style="display: none;"> We find that stray infrared light from the 4 K stage in a cryostat can cause significant loss in superconducting resonators and qubits. For devices shielded in only a metal box, we measured resonators with quality factors Q = 10^5 and qubits with energy relaxation times T_1=120 ns, consistent with a stray light-induced quasiparticle density of 170-230 渭m^{-3}. By adding a second black shield at the sample temperature, we found about an order of magnitude improvement in performance and no sensitivity to the 4 K radiation. We also tested various shielding methods, implying a lower limit of Q = 10^8 due to stray light in the light-tight configuration. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1105.4642v1-abstract-full').style.display = 'none'; document.getElementById('1105.4642v1-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> 23 May, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2011. </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> Appl. Phys. Lett. 99, 113507 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1103.6094">arXiv:1103.6094</a> <span> [<a href="https://arxiv.org/pdf/1103.6094">pdf</a>, <a href="https://arxiv.org/format/1103.6094">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="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/10.1063/1.3595942">10.1063/1.3595942 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High Q-factor Sapphire Whispering Gallery Mode Microwave Resonator at Single Photon Energies and milli-Kelvin Temperatures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Creedon%2C+D+L">Daniel L. Creedon</a>, <a href="/search/cond-mat?searchtype=author&query=Reshitnyk%2C+Y">Yarema Reshitnyk</a>, <a href="/search/cond-mat?searchtype=author&query=Farr%2C+W">Warrick Farr</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=Duty%2C+T+L">Timothy L. Duty</a>, <a href="/search/cond-mat?searchtype=author&query=Tobar%2C+M+E">Michael E. Tobar</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="1103.6094v2-abstract-short" style="display: inline;"> The microwave properties of a crystalline sapphire dielectric whispering gallery mode resonator have been measured at very low excitation strength (E/hf=1) and low temperatures (T = 30 mK). The measurements were sensitive enough to observe saturation due to a highly detuned electron spin resonance, which limited the loss tangent of the material to about 2e-8 measured at 13.868 and 13.259 GHz. Smal… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1103.6094v2-abstract-full').style.display = 'inline'; document.getElementById('1103.6094v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1103.6094v2-abstract-full" style="display: none;"> The microwave properties of a crystalline sapphire dielectric whispering gallery mode resonator have been measured at very low excitation strength (E/hf=1) and low temperatures (T = 30 mK). The measurements were sensitive enough to observe saturation due to a highly detuned electron spin resonance, which limited the loss tangent of the material to about 2e-8 measured at 13.868 and 13.259 GHz. Small power dependent frequency shifts were also measured which correspond to an added magnetic susceptibility of order 1e-9. This work shows that quantum limited microwave resonators with Q-factors > 1e8 are possible with the implementation of a sapphire whispering gallery mode system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1103.6094v2-abstract-full').style.display = 'none'; document.getElementById('1103.6094v2-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 March, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 March, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2011. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1101.0862">arXiv:1101.0862</a> <span> [<a href="https://arxiv.org/pdf/1101.0862">pdf</a>, <a href="https://arxiv.org/ps/1101.0862">ps</a>, <a href="https://arxiv.org/format/1101.0862">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/PhysRevB.84.024501">10.1103/PhysRevB.84.024501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Energy decay and frequency shift of a superconducting qubit from non-equilibrium quasiparticles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lenander%2C+M">M. Lenander</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</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=Mariantoni%2C+M">Matteo Mariantoni</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=Yamamoto%2C+T">T. Yamamoto</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</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="1101.0862v1-abstract-short" style="display: inline;"> Quasiparticles are an important decoherence mechanism in superconducting qubits, and can be described with a complex admittance that is a generalization of the Mattis-Bardeen theory. By injecting non-equilibrium quasiparticles with a tunnel junction, we verify qualitatively the expected change of the decay rate and frequency in a phase qubit. With their relative change in agreement to within 4% of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.0862v1-abstract-full').style.display = 'inline'; document.getElementById('1101.0862v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1101.0862v1-abstract-full" style="display: none;"> Quasiparticles are an important decoherence mechanism in superconducting qubits, and can be described with a complex admittance that is a generalization of the Mattis-Bardeen theory. By injecting non-equilibrium quasiparticles with a tunnel junction, we verify qualitatively the expected change of the decay rate and frequency in a phase qubit. With their relative change in agreement to within 4% of prediction, the theory can be reliably used to infer quasiparticle density. We describe how settling of the decay rate may allow determination of whether qubit energy relaxation is limited by non-equilibrium quasiparticles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1101.0862v1-abstract-full').style.display = 'none'; document.getElementById('1101.0862v1-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 January, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2011. </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 paper: 4 pages, 3 figures, 1 table. Supplementary material: 8 pages, 3 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 84, 024501 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1011.4982">arXiv:1011.4982</a> <span> [<a href="https://arxiv.org/pdf/1011.4982">pdf</a>, <a href="https://arxiv.org/ps/1011.4982">ps</a>, <a href="https://arxiv.org/format/1011.4982">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/10.1088/0953-2048/24/6/065001">10.1088/0953-2048/24/6/065001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Wirebond crosstalk and cavity modes in large chip mounts for superconducting qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wenner%2C+J">J. Wenner</a>, <a href="/search/cond-mat?searchtype=author&query=Neeley%2C+M">M. Neeley</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=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=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=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="1011.4982v1-abstract-short" style="display: inline;"> We analyze the performance of a microwave chip mount that uses wirebonds to connect the chip and mount grounds. A simple impedance ladder model predicts that transmission crosstalk between two feedlines falls off exponentially with distance at low frequencies, but rises to near unity above a resonance frequency set by the chip to ground capacitance. Using SPICE simulations and experimental measure… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1011.4982v1-abstract-full').style.display = 'inline'; document.getElementById('1011.4982v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1011.4982v1-abstract-full" style="display: none;"> We analyze the performance of a microwave chip mount that uses wirebonds to connect the chip and mount grounds. A simple impedance ladder model predicts that transmission crosstalk between two feedlines falls off exponentially with distance at low frequencies, but rises to near unity above a resonance frequency set by the chip to ground capacitance. Using SPICE simulations and experimental measurements of a scale model, the basic predictions of the ladder model were verified. In particular, by decreasing the capacitance between the chip and box grounds, the resonance frequency increased and transmission decreased. This model then influenced the design of a new mount that improved the isolation to -65 dB at 6 GHz, even though the chip dimensions were increased to 1 cm by 1 cm, 3 times as large as our previous devices. We measured a coplanar resonator in this mount as preparation for larger qubit chips, and were able to identify cavity, slotline, and resonator modes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1011.4982v1-abstract-full').style.display = 'none'; document.getElementById('1011.4982v1-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, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">13 pages, 7 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Supercond. Sci. Technol. 24, 065001 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1011.3080">arXiv:1011.3080</a> <span> [<a href="https://arxiv.org/pdf/1011.3080">pdf</a>, <a href="https://arxiv.org/format/1011.3080">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="Optics">physics.optics</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/nphys1885">10.1038/nphys1885 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Photon shell game in three-resonator circuit quantum electrodynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Mariantoni%2C+M">Matteo Mariantoni</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">H. Wang</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=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=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=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</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=Cleland%2C+A+N">A. N. Cleland</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="1011.3080v3-abstract-short" style="display: inline;"> The generation and control of quantum states of light constitute fundamental tasks in cavity quantum electrodynamics (QED). The superconducting realization of cavity QED, circuit QED, enables on-chip microwave photonics, where superconducting qubits control and measure individual photon states. A long-standing issue in cavity QED is the coherent transfer of photons between two or more resonators.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1011.3080v3-abstract-full').style.display = 'inline'; document.getElementById('1011.3080v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1011.3080v3-abstract-full" style="display: none;"> The generation and control of quantum states of light constitute fundamental tasks in cavity quantum electrodynamics (QED). The superconducting realization of cavity QED, circuit QED, enables on-chip microwave photonics, where superconducting qubits control and measure individual photon states. A long-standing issue in cavity QED is the coherent transfer of photons between two or more resonators. Here, we use circuit QED to implement a three-resonator architecture on a single chip, where the resonators are interconnected by two superconducting phase qubits. We use this circuit to shuffle one- and two-photon Fock states between the three resonators, and demonstrate qubit-mediated vacuum Rabi swaps between two resonators. This illustrates the potential for using multi-resonator circuits as photon quantum registries and for creating multipartite entanglement between delocalized bosonic modes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1011.3080v3-abstract-full').style.display = 'none'; document.getElementById('1011.3080v3-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> 16 March, 2011; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 November, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">18 pages, 10 figures, 1 table. DOI refers to published paper on Nature Physics, not to the pre-review version posted here</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1011.2862">arXiv:1011.2862</a> <span> [<a href="https://arxiv.org/pdf/1011.2862">pdf</a>, <a href="https://arxiv.org/ps/1011.2862">ps</a>, <a href="https://arxiv.org/format/1011.2862">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/PhysRevLett.106.060401">10.1103/PhysRevLett.106.060401 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Deterministic entanglement of photons in two superconducting microwave 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=Mariantoni%2C+M">Matteo Mariantoni</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=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">A. 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=Yamamoto%2C+T">T. Yamamoto</a>, <a href="/search/cond-mat?searchtype=author&query=Yin%2C+Y">Y. Yin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+J">J. Zhao</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=Cleland%2C+A+N">A. N. Cleland</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="1011.2862v1-abstract-short" style="display: inline;"> Quantum entanglement, one of the defining features of quantum mechanics, has been demonstrated in a variety of nonlinear spin-like systems. Quantum entanglement in linear systems has proven significantly more challenging, as the intrinsic energy level degeneracy associated with linearity makes quantum control more difficult. Here we demonstrate the quantum entanglement of photon states in two inde… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1011.2862v1-abstract-full').style.display = 'inline'; document.getElementById('1011.2862v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1011.2862v1-abstract-full" style="display: none;"> Quantum entanglement, one of the defining features of quantum mechanics, has been demonstrated in a variety of nonlinear spin-like systems. Quantum entanglement in linear systems has proven significantly more challenging, as the intrinsic energy level degeneracy associated with linearity makes quantum control more difficult. Here we demonstrate the quantum entanglement of photon states in two independent linear microwave resonators, creating N-photon NOON states as a benchmark demonstration. We use a superconducting quantum circuit that includes Josephson qubits to control and measure the two resonators, and we completely characterize the entangled states with bipartite Wigner tomography. These results demonstrate a significant advance in the quantum control of linear resonators in superconducting circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1011.2862v1-abstract-full').style.display = 'none'; document.getElementById('1011.2862v1-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 November, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">11 pages, 11 figures, and 3 tables including supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 106, 060401 (2011) </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=Martinis%2C+J+M&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Martinis%2C+J+M&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Martinis%2C+J+M&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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