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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.02105">arXiv:2108.02105</a> <span> [<a href="https://arxiv.org/pdf/2108.02105">pdf</a>, <a href="https://arxiv.org/format/2108.02105">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.17.024058">10.1103/PhysRevApplied.17.024058 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterisation of spatial charge sensitivity in a multi-mode superconducting qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">J. Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">G. Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">S. Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">S. D. Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">P. J. Leek</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.02105v1-abstract-short" style="display: inline;"> Understanding and suppressing sources of decoherence is a leading challenge in building practical quantum computers. In superconducting qubits, low frequency charge noise is a well-known decoherence mechanism that is effectively suppressed in the transmon qubit. Devices with multiple charge-sensitive modes can exhibit more complex behaviours, which can be exploited to study charge fluctuations in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.02105v1-abstract-full').style.display = 'inline'; document.getElementById('2108.02105v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.02105v1-abstract-full" style="display: none;"> Understanding and suppressing sources of decoherence is a leading challenge in building practical quantum computers. In superconducting qubits, low frequency charge noise is a well-known decoherence mechanism that is effectively suppressed in the transmon qubit. Devices with multiple charge-sensitive modes can exhibit more complex behaviours, which can be exploited to study charge fluctuations in superconducting qubits. Here we characterise charge-sensitivity in a superconducting qubit with two transmon-like modes, each of which is sensitive to multiple charge-parity configurations and charge-offset biases. Using Ramsey interferometry, we observe sensitivity to four charge-parity configurations and track two independent charge-offset drifts over hour timescales. We provide a predictive theory for charge sensitivity in such multi-mode qubits which agrees with our results. Finally, we demonstrate the utility of a multi-mode qubit as a charge detector by spatially tracking local-charge drift. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.02105v1-abstract-full').style.display = 'none'; document.getElementById('2108.02105v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main: 6 pages, 4 figures. Appendices: 3 pages, 3 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 17, 024058 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.11140">arXiv:2107.11140</a> <span> [<a href="https://arxiv.org/pdf/2107.11140">pdf</a>, <a href="https://arxiv.org/format/2107.11140">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> High Coherence in a Tileable 3D Integrated Superconducting Circuit Architecture </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Spring%2C+P+A">Peter A. Spring</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Tsunoda%2C+T">Takahiro Tsunoda</a>, <a href="/search/quant-ph?searchtype=author&query=Campanaro%2C+G">Giulio Campanaro</a>, <a href="/search/quant-ph?searchtype=author&query=Fasciati%2C+S+D">Simone D. Fasciati</a>, <a href="/search/quant-ph?searchtype=author&query=Wills%2C+J">James Wills</a>, <a href="/search/quant-ph?searchtype=author&query=Chidambaram%2C+V">Vivek Chidambaram</a>, <a href="/search/quant-ph?searchtype=author&query=Shteynas%2C+B">Boris Shteynas</a>, <a href="/search/quant-ph?searchtype=author&query=Bakr%2C+M">Mustafa Bakr</a>, <a href="/search/quant-ph?searchtype=author&query=Gow%2C+P">Paul Gow</a>, <a href="/search/quant-ph?searchtype=author&query=Carpenter%2C+L">Lewis Carpenter</a>, <a href="/search/quant-ph?searchtype=author&query=Gates%2C+J">James Gates</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">Peter J. Leek</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.11140v1-abstract-short" style="display: inline;"> We report high qubit coherence as well as low crosstalk and single-qubit gate errors in a superconducting circuit architecture that promises to be tileable to 2D lattices of qubits. The architecture integrates an inductively shunted cavity enclosure into a design featuring non-galvanic out-of-plane control wiring and qubits and resonators fabricated on opposing sides of a substrate. The proof-of-p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.11140v1-abstract-full').style.display = 'inline'; document.getElementById('2107.11140v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.11140v1-abstract-full" style="display: none;"> We report high qubit coherence as well as low crosstalk and single-qubit gate errors in a superconducting circuit architecture that promises to be tileable to 2D lattices of qubits. The architecture integrates an inductively shunted cavity enclosure into a design featuring non-galvanic out-of-plane control wiring and qubits and resonators fabricated on opposing sides of a substrate. The proof-of-principle device features four uncoupled transmon qubits and exhibits average energy relaxation times $T_1=149(38)~渭$s, pure echoed dephasing times $T_{蠁,e}=189(34)~渭$s, and single-qubit gate fidelities $F=99.982(4)\%$ as measured by simultaneous randomized benchmarking. The 3D integrated nature of the control wiring means that qubits will remain addressable as the architecture is tiled to form larger qubit lattices. Band structure simulations are used to predict that the tiled enclosure will still provide a clean electromagnetic environment to enclosed qubits at arbitrary scale. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.11140v1-abstract-full').style.display = 'none'; document.getElementById('2107.11140v1-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main: 8 pages, 7 figures, 3 tables. Appendices: 8 pages, 9 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/1910.03902">arXiv:1910.03902</a> <span> [<a href="https://arxiv.org/pdf/1910.03902">pdf</a>, <a href="https://arxiv.org/format/1910.03902">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.101.052309">10.1103/PhysRevA.101.052309 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cost function embedding and dataset encoding for machine learning with parameterized quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+S">Shuxiang Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wossnig%2C+L">Leonard Wossnig</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P">Peter Leek</a>, <a href="/search/quant-ph?searchtype=author&query=Grant%2C+E">Edward Grant</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="1910.03902v1-abstract-short" style="display: inline;"> Machine learning is seen as a promising application of quantum computation. For near-term noisy intermediate-scale quantum (NISQ) devices, parametrized quantum circuits (PQCs) have been proposed as machine learning models due to their robustness and ease of implementation. However, the cost function is normally calculated classically from repeated measurement outcomes, such that it is no longer en… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03902v1-abstract-full').style.display = 'inline'; document.getElementById('1910.03902v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.03902v1-abstract-full" style="display: none;"> Machine learning is seen as a promising application of quantum computation. For near-term noisy intermediate-scale quantum (NISQ) devices, parametrized quantum circuits (PQCs) have been proposed as machine learning models due to their robustness and ease of implementation. However, the cost function is normally calculated classically from repeated measurement outcomes, such that it is no longer encoded in a quantum state. This prevents the value from being directly manipulated by a quantum computer. To solve this problem, we give a routine to embed the cost function for machine learning into a quantum circuit, which accepts a training dataset encoded in superposition or an easily preparable mixed state. We also demonstrate the ability to evaluate the gradient of the encoded cost function in a quantum state. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03902v1-abstract-full').style.display = 'none'; document.getElementById('1910.03902v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 101, 052309 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1909.02104">arXiv:1909.02104</a> <span> [<a href="https://arxiv.org/pdf/1909.02104">pdf</a>, <a href="https://arxiv.org/format/1909.02104">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/10.1103/PhysRevApplied.14.024061">10.1103/PhysRevApplied.14.024061 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Modelling Enclosures for Large-Scale Superconducting Quantum Circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Spring%2C+P+A">P. A. Spring</a>, <a href="/search/quant-ph?searchtype=author&query=Tsunoda%2C+T">T. Tsunoda</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">P. J. Leek</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="1909.02104v2-abstract-short" style="display: inline;"> Superconducting quantum circuits are typically housed in conducting enclosures in order to control their electromagnetic environment. As devices grow in physical size, the electromagnetic modes of the enclosure come down in frequency and can introduce unwanted long-range cross-talk between distant elements of the enclosed circuit. Incorporating arrays of inductive shunts such as through-substrate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.02104v2-abstract-full').style.display = 'inline'; document.getElementById('1909.02104v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1909.02104v2-abstract-full" style="display: none;"> Superconducting quantum circuits are typically housed in conducting enclosures in order to control their electromagnetic environment. As devices grow in physical size, the electromagnetic modes of the enclosure come down in frequency and can introduce unwanted long-range cross-talk between distant elements of the enclosed circuit. Incorporating arrays of inductive shunts such as through-substrate vias or machined pillars can suppress these effects by raising these mode frequencies. Here, we derive simple, accurate models for the modes of enclosures that incorporate such inductive-shunt arrays. We use these models to predict that cavity-mediated inter-qubit couplings and drive-line cross-talk are exponentially suppressed with distance for arbitrarily large quantum circuits housed in such enclosures, indicating the promise of this approach for quantum computing. We find good agreement with a finite-element simulation of an example device containing more than 400 qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.02104v2-abstract-full').style.display = 'none'; document.getElementById('1909.02104v2-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 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 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">6 pages + appendix, 6 figures in main text + 4 in appendix</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 14, 024061 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.05670">arXiv:1905.05670</a> <span> [<a href="https://arxiv.org/pdf/1905.05670">pdf</a>, <a href="https://arxiv.org/format/1905.05670">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.12.064013">10.1103/PhysRevApplied.12.064013 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Calibration of the cross-resonance two-qubit gate between directly-coupled transmons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Patterson%2C+A+D">A. D. Patterson</a>, <a href="/search/quant-ph?searchtype=author&query=Rahamim%2C+J">J. Rahamim</a>, <a href="/search/quant-ph?searchtype=author&query=Tsunoda%2C+T">T. Tsunoda</a>, <a href="/search/quant-ph?searchtype=author&query=Spring%2C+P">P. Spring</a>, <a href="/search/quant-ph?searchtype=author&query=Jebari%2C+S">S. Jebari</a>, <a href="/search/quant-ph?searchtype=author&query=Ratter%2C+K">K. Ratter</a>, <a href="/search/quant-ph?searchtype=author&query=Mergenthaler%2C+M">M. Mergenthaler</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">G. Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Esposito%2C+M">M. Esposito</a>, <a href="/search/quant-ph?searchtype=author&query=Leek%2C+P+J">P. J. Leek</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="1905.05670v1-abstract-short" style="display: inline;"> Quantum computation requires the precise control of the evolution of a quantum system, typically through application of discrete quantum logic gates on a set of qubits. Here, we use the cross-resonance interaction to implement a gate between two superconducting transmon qubits with a direct static dispersive coupling. We demonstrate a practical calibration procedure for the optimization of the gat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.05670v1-abstract-full').style.display = 'inline'; document.getElementById('1905.05670v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.05670v1-abstract-full" style="display: none;"> Quantum computation requires the precise control of the evolution of a quantum system, typically through application of discrete quantum logic gates on a set of qubits. Here, we use the cross-resonance interaction to implement a gate between two superconducting transmon qubits with a direct static dispersive coupling. We demonstrate a practical calibration procedure for the optimization of the gate, combining continuous and repeated-gate Hamiltonian tomography with step-wise reduction of dominant two-qubit coherent errors through mapping to microwave control parameters. We show experimentally that this procedure can enable a $\hat{ZX}_{-蟺/2}$ gate with a fidelity $F=97.0(7)\%$, measured with interleaved randomized benchmarking. We show this in a architecture with out-of-plane control and readout that is readily extensible to larger scale quantum circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.05670v1-abstract-full').style.display = 'none'; document.getElementById('1905.05670v1-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 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">8 pages, 6 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 12, 064013 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1606.00817">arXiv:1606.00817</a> <span> [<a href="https://arxiv.org/pdf/1606.00817">pdf</a>, <a href="https://arxiv.org/format/1606.00817">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevX.6.031041">10.1103/PhysRevX.6.031041 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Implementing and characterizing precise multi-qubit measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Blumoff%2C+J+Z">J. Z. Blumoff</a>, <a href="/search/quant-ph?searchtype=author&query=Chou%2C+K">K. Chou</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+C">C. Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Reagor%2C+M">M. Reagor</a>, <a href="/search/quant-ph?searchtype=author&query=Axline%2C+C">C. Axline</a>, <a href="/search/quant-ph?searchtype=author&query=Brierley%2C+R+T">R. T. Brierley</a>, <a href="/search/quant-ph?searchtype=author&query=Silveri%2C+M+P">M. P. Silveri</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">C. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Nigg%2C+S+E">S. E. Nigg</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">L. Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M+H">M. H. Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">L. Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Girvin%2C+S+M">S. M. Girvin</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">R. J. Schoelkopf</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="1606.00817v2-abstract-short" style="display: inline;"> There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. We realize such… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.00817v2-abstract-full').style.display = 'inline'; document.getElementById('1606.00817v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1606.00817v2-abstract-full" style="display: none;"> There are two general requirements to harness the computational power of quantum mechanics: the ability to manipulate the evolution of an isolated system and the ability to faithfully extract information from it. Quantum error correction and simulation often make a more exacting demand: the ability to perform non-destructive measurements of specific correlations within that system. We realize such measurements by employing a protocol adapted from [S. Nigg and S. M. Girvin, Phys. Rev. Lett. 110, 243604 (2013)], enabling real-time selection of arbitrary register-wide Pauli operators. Our implementation consists of a simple circuit quantum electrodynamics (cQED) module of four highly-coherent 3D transmon qubits, collectively coupled to a high-Q superconducting microwave cavity. As a demonstration, we enact all seven nontrivial subset-parity measurements on our three-qubit register. For each we fully characterize the realized measurement by analyzing the detector (observable operators) via quantum detector tomography and by analyzing the quantum back-action via conditioned process tomography. No single quantity completely encapsulates the performance of a measurement, and standard figures of merit have not yet emerged. Accordingly, we consider several new fidelity measures for both the detector and the complete measurement process. We measure all of these quantities and report high fidelities, indicating that we are measuring the desired quantities precisely and that the measurements are highly non-demolition. We further show that both results are improved significantly by an additional error-heralding measurement. The analyses presented here form a useful basis for the future characterization and validation of quantum measurements, anticipating the demands of emerging quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.00817v2-abstract-full').style.display = 'none'; document.getElementById('1606.00817v2-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 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">10 pages, 5 figures, plus supplement</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. X 6, 031041 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1602.04768">arXiv:1602.04768</a> <span> [<a href="https://arxiv.org/pdf/1602.04768">pdf</a>, <a href="https://arxiv.org/format/1602.04768">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Demonstrating Quantum Error Correction that Extends the Lifetime of Quantum Information </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ofek%2C+N">Nissim Ofek</a>, <a href="/search/quant-ph?searchtype=author&query=Petrenko%2C+A">Andrei Petrenko</a>, <a href="/search/quant-ph?searchtype=author&query=Heeres%2C+R">Reinier Heeres</a>, <a href="/search/quant-ph?searchtype=author&query=Reinhold%2C+P">Philip Reinhold</a>, <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Zaki Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yehan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">Luigi Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Girvin%2C+S+M">S. M. Girvin</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">Mazyar Mirrahimi</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M+H">M. H. Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">R. J. Schoelkopf</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="1602.04768v1-abstract-short" style="display: inline;"> The remarkable discovery of Quantum Error Correction (QEC), which can overcome the errors experienced by a bit of quantum information (qubit), was a critical advance that gives hope for eventually realizing practical quantum computers. In principle, a system that implements QEC can actually pass a "break-even" point and preserve quantum information for longer than the lifetime of its constituent p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.04768v1-abstract-full').style.display = 'inline'; document.getElementById('1602.04768v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1602.04768v1-abstract-full" style="display: none;"> The remarkable discovery of Quantum Error Correction (QEC), which can overcome the errors experienced by a bit of quantum information (qubit), was a critical advance that gives hope for eventually realizing practical quantum computers. In principle, a system that implements QEC can actually pass a "break-even" point and preserve quantum information for longer than the lifetime of its constituent parts. Reaching the break-even point, however, has thus far remained an outstanding and challenging goal. Several previous works have demonstrated elements of QEC in NMR, ions, nitrogen vacancy (NV) centers, photons, and superconducting transmons. However, these works primarily illustrate the signatures or scaling properties of QEC codes rather than test the capacity of the system to extend the lifetime of quantum information over time. Here we demonstrate a QEC system that reaches the break-even point by suppressing the natural errors due to energy loss for a qubit logically encoded in superpositions of coherent states, or cat states of a superconducting resonator. Moreover, the experiment implements a full QEC protocol by using real-time feedback to encode, monitor naturally occurring errors, decode, and correct. As measured by full process tomography, the enhanced lifetime of the encoded information is 320 microseconds without any post-selection. This is 20 times greater than that of the system's transmon, over twice as long as an uncorrected logical encoding, and 10% longer than the highest quality element of the system (the resonator's 0, 1 Fock states). Our results illustrate the power of novel, hardware efficient qubit encodings over traditional QEC schemes. Furthermore, they advance the field of experimental error correction from confirming the basic concepts to exploring the metrics that drive system performance and the challenges in implementing a fault-tolerant system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.04768v1-abstract-full').style.display = 'none'; document.getElementById('1602.04768v1-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 February, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2016. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1504.03382">arXiv:1504.03382</a> <span> [<a href="https://arxiv.org/pdf/1504.03382">pdf</a>, <a href="https://arxiv.org/format/1504.03382">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.115.180501">10.1103/PhysRevLett.115.180501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Single-photon Resolved Cross-Kerr Interaction for Autonomous Stabilization of Photon-number States </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Holland%2C+E+T">E. T. Holland</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Heeres%2C+R+W">R. W. Heeres</a>, <a href="/search/quant-ph?searchtype=author&query=Reagor%2C+M+J">M. J. Reagor</a>, <a href="/search/quant-ph?searchtype=author&query=Vool%2C+U">U. Vool</a>, <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Z. Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">L. Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Kirchmair%2C+G">G. Kirchmair</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M+H">M. H. Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">M. Mirrahimi</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">R. J. Schoelkopf</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="1504.03382v1-abstract-short" style="display: inline;"> Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying active feedback conditioned on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state through a combination of drives and designed entropy evacuation. We propose and implement a quantum reservoir engineering protocol that stabilizes Fock s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.03382v1-abstract-full').style.display = 'inline'; document.getElementById('1504.03382v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1504.03382v1-abstract-full" style="display: none;"> Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying active feedback conditioned on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state through a combination of drives and designed entropy evacuation. We propose and implement a quantum reservoir engineering protocol that stabilizes Fock states in a microwave cavity. This protocol is realized with a circuit quantum electrodynamics platform where a Josephson junction provides direct, nonlinear coupling between two superconducting waveguide cavities. The nonlinear coupling results in a single photon resolved cross-Kerr effect between the two cavities enabling a photon number dependent coupling to a lossy environment. The quantum state of the microwave cavity is discussed in terms of a net polarization and is analyzed by a measurement of its steady state Wigner function. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.03382v1-abstract-full').style.display = 'none'; document.getElementById('1504.03382v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">8 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 115, 180501 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1504.02512">arXiv:1504.02512</a> <span> [<a href="https://arxiv.org/pdf/1504.02512">pdf</a>, <a href="https://arxiv.org/format/1504.02512">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Violating Bell's inequality with an artificial atom and a cat state in a cavity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Petrenko%2C+A">Andrei Petrenko</a>, <a href="/search/quant-ph?searchtype=author&query=Ofek%2C+N">Nissim Ofek</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">Luayn Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Zaki Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Sliwa%2C+K">Katrina Sliwa</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yehan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Hatridge%2C+M">Michael Hatridge</a>, <a href="/search/quant-ph?searchtype=author&query=Blumoff%2C+J">Jacob Blumoff</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">Luigi Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">Mazyar Mirrahimi</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M+H">M. H. Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">R. J. Schoelkopf</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="1504.02512v1-abstract-short" style="display: inline;"> The `Schr枚dinger's cat' thought experiment highlights the counterintuitive facet of quantum theory that entanglement can exist between microscopic and macroscopic systems, producing a superposition of distinguishable states like the fictitious cat that is both alive and dead. The hallmark of entanglement is the detection of strong correlations between systems, for example by the violation of Bell'… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.02512v1-abstract-full').style.display = 'inline'; document.getElementById('1504.02512v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1504.02512v1-abstract-full" style="display: none;"> The `Schr枚dinger's cat' thought experiment highlights the counterintuitive facet of quantum theory that entanglement can exist between microscopic and macroscopic systems, producing a superposition of distinguishable states like the fictitious cat that is both alive and dead. The hallmark of entanglement is the detection of strong correlations between systems, for example by the violation of Bell's inequality. Using the CHSH variant of the Bell test, this violation has been observed with photons, atoms, solid state spins, and artificial atoms in superconducting circuits. For larger, more distinguishable states, the conflict between quantum predictions and our classical expectations is typically resolved due to the rapid onset of decoherence. To investigate this reconciliation, one can employ a superposition of coherent states in an oscillator, known as a cat state. In contrast to discrete systems, one can continuously vary the size of the prepared cat state and therefore its dependence on decoherence. Here we demonstrate and quantify entanglement between an artificial atom and a cat state in a cavity, which we call a `Bell-cat' state. We use a circuit QED architecture, high-fidelity measurements, and real-time feedback control to violate Bell's inequality without post-selection or corrections for measurement inefficiencies. Furthermore, we investigate the influence of decoherence by continuously varying the size of created Bell-cat states and characterize the entangled system by joint Wigner tomography. These techniques provide a toolset for quantum information processing with entangled qubits and resonators. While recent results have demonstrated a high level of control of such systems, this experiment demonstrates that information can be extracted efficiently and with high fidelity, a crucial requirement for quantum computing with resonators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.02512v1-abstract-full').style.display = 'none'; document.getElementById('1504.02512v1-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 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/1503.01496">arXiv:1503.01496</a> <span> [<a href="https://arxiv.org/pdf/1503.01496">pdf</a>, <a href="https://arxiv.org/format/1503.01496">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.115.137002">10.1103/PhysRevLett.115.137002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cavity State Manipulation Using Photon-Number Selective Phase Gates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Heeres%2C+R+W">Reinier W. Heeres</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Holland%2C+E">Eric Holland</a>, <a href="/search/quant-ph?searchtype=author&query=Krastanov%2C+S">Stefan Krastanov</a>, <a href="/search/quant-ph?searchtype=author&query=Albert%2C+V+V">Victor V. Albert</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">Luigi Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">Robert J. Schoelkopf</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="1503.01496v1-abstract-short" style="display: inline;"> The large available Hilbert space and high coherence of cavity resonators makes these systems an interesting resource for storing encoded quantum bits. To perform a quantum gate on this encoded information, however, complex nonlinear operations must be applied to the many levels of the oscillator simultaneously. In this work, we introduce the Selective Number-dependent Arbitrary Phase (SNAP) gate,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.01496v1-abstract-full').style.display = 'inline'; document.getElementById('1503.01496v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1503.01496v1-abstract-full" style="display: none;"> The large available Hilbert space and high coherence of cavity resonators makes these systems an interesting resource for storing encoded quantum bits. To perform a quantum gate on this encoded information, however, complex nonlinear operations must be applied to the many levels of the oscillator simultaneously. In this work, we introduce the Selective Number-dependent Arbitrary Phase (SNAP) gate, which imparts a different phase to each Fock state component using an off-resonantly coupled qubit. We show that the SNAP gate allows control over the quantum phases by correcting the unwanted phase evolution due to the Kerr effect. Furthermore, by combining the SNAP gate with oscillator displacements, we create a one-photon Fock state with high fidelity. Using just these two controls, one can construct arbitrary unitary operations, offering a scalable route to performing logical manipulations on oscillator-encoded qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.01496v1-abstract-full').style.display = 'none'; document.getElementById('1503.01496v1-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 March, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">9 pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 115, 137002 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1502.08015">arXiv:1502.08015</a> <span> [<a href="https://arxiv.org/pdf/1502.08015">pdf</a>, <a href="https://arxiv.org/format/1502.08015">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/PhysRevA.92.040303">10.1103/PhysRevA.92.040303 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Universal Control of an Oscillator with Dispersive Coupling to a Qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Krastanov%2C+S">Stefan Krastanov</a>, <a href="/search/quant-ph?searchtype=author&query=Albert%2C+V+V">Victor V. Albert</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+C">Chao Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Heeres%2C+R+W">Reinier W. Heeres</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">Robert J. Schoelkopf</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</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="1502.08015v2-abstract-short" style="display: inline;"> We investigate quantum control of an oscillator mode off-resonantly coupled to an ancillary qubit. In the strong dispersive regime, we may drive the qubit conditioned on number states of the oscillator, which together with displacement operations can achieve universal control of the oscillator. Based on our proof of universal control, we provide explicit constructions for arbitrary state preparati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.08015v2-abstract-full').style.display = 'inline'; document.getElementById('1502.08015v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1502.08015v2-abstract-full" style="display: none;"> We investigate quantum control of an oscillator mode off-resonantly coupled to an ancillary qubit. In the strong dispersive regime, we may drive the qubit conditioned on number states of the oscillator, which together with displacement operations can achieve universal control of the oscillator. Based on our proof of universal control, we provide explicit constructions for arbitrary state preparation and arbitrary unitary operation of the oscillator. Moreover, we present an efficient procedure to prepare the number state $\left|n\right\rangle$ using only $O\left(\sqrt{n}\right)$ operations. We also compare our scheme with known quantum control protocols for coupled qubit-oscillator systems. This universal control scheme of the oscillator can readily be implemented using superconducting circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.08015v2-abstract-full').style.display = 'none'; document.getElementById('1502.08015v2-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 March, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 February, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">5 pages, 3 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 92, 040303(R) (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1412.4633">arXiv:1412.4633</a> <span> [<a href="https://arxiv.org/pdf/1412.4633">pdf</a>, <a href="https://arxiv.org/format/1412.4633">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.aaa2085">10.1126/science.aaa2085 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Confining the state of light to a quantum manifold by engineered two-photon loss </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Zaki Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Touzard%2C+S">Steven Touzard</a>, <a href="/search/quant-ph?searchtype=author&query=Pop%2C+I+M">Ioan M. Pop</a>, <a href="/search/quant-ph?searchtype=author&query=Kou%2C+A">Angela Kou</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Petrenko%2C+A">Andrei Petrenko</a>, <a href="/search/quant-ph?searchtype=author&query=Sliwa%2C+K+M">Katrina M. Sliwa</a>, <a href="/search/quant-ph?searchtype=author&query=Narla%2C+A">Anirudh Narla</a>, <a href="/search/quant-ph?searchtype=author&query=Shankar%2C+S">Shyam Shankar</a>, <a href="/search/quant-ph?searchtype=author&query=Hatridge%2C+M+J">Michael J. Hatridge</a>, <a href="/search/quant-ph?searchtype=author&query=Reagor%2C+M">Matthew Reagor</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">Luigi Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">Robert J. Schoelkopf</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">Mazyar Mirrahimi</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M+H">Michel H. Devoret</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="1412.4633v1-abstract-short" style="display: inline;"> Physical systems usually exhibit quantum behavior, such as superpositions and entanglement, only when they are sufficiently decoupled from a lossy environment. Paradoxically, a specially engineered interaction with the environment can become a resource for the generation and protection of quantum states. This notion can be generalized to the confinement of a system into a manifold of quantum state… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1412.4633v1-abstract-full').style.display = 'inline'; document.getElementById('1412.4633v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1412.4633v1-abstract-full" style="display: none;"> Physical systems usually exhibit quantum behavior, such as superpositions and entanglement, only when they are sufficiently decoupled from a lossy environment. Paradoxically, a specially engineered interaction with the environment can become a resource for the generation and protection of quantum states. This notion can be generalized to the confinement of a system into a manifold of quantum states, consisting of all coherent superpositions of multiple stable steady states. We have experimentally confined the state of a harmonic oscillator to the quantum manifold spanned by two coherent states of opposite phases. In particular, we have observed a Schrodinger cat state spontaneously squeeze out of vacuum, before decaying into a classical mixture. This was accomplished by designing a superconducting microwave resonator whose coupling to a cold bath is dominated by photon pair exchange. This experiment opens new avenues in the fields of nonlinear quantum optics and quantum information, where systems with multi-dimensional steady state manifolds can be used as error corrected logical qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1412.4633v1-abstract-full').style.display = 'none'; document.getElementById('1412.4633v1-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 December, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science (2015), Vol. 347, No. 6224 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1311.2534">arXiv:1311.2534</a> <span> [<a href="https://arxiv.org/pdf/1311.2534">pdf</a>, <a href="https://arxiv.org/ps/1311.2534">ps</a>, <a href="https://arxiv.org/format/1311.2534">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/10.1038/nature13436">10.1038/nature13436 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tracking Photon Jumps with Repeated Quantum Non-Demolition Parity Measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sun%2C+L">L. Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Petrenko%2C+A">A. Petrenko</a>, <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Z. Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">B. Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Kirchmair%2C+G">G. Kirchmair</a>, <a href="/search/quant-ph?searchtype=author&query=Sliwa%2C+K+M">K. M. Sliwa</a>, <a href="/search/quant-ph?searchtype=author&query=Narla%2C+A">A. Narla</a>, <a href="/search/quant-ph?searchtype=author&query=Hatridge%2C+M">M. Hatridge</a>, <a href="/search/quant-ph?searchtype=author&query=Shankar%2C+S">S. Shankar</a>, <a href="/search/quant-ph?searchtype=author&query=Blumoff%2C+J">J. Blumoff</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">L. Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">M. Mirrahimi</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M+H">M. H. Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">R. J. Schoelkopf</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="1311.2534v1-abstract-short" style="display: inline;"> Quantum error correction (QEC) is required for a practical quantum computer because of the fragile nature of quantum information. In QEC, information is redundantly stored in a large Hilbert space and one or more observables must be monitored to reveal the occurrence of an error, without disturbing the information encoded in an unknown quantum state. Such observables, typically multi-qubit paritie… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1311.2534v1-abstract-full').style.display = 'inline'; document.getElementById('1311.2534v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1311.2534v1-abstract-full" style="display: none;"> Quantum error correction (QEC) is required for a practical quantum computer because of the fragile nature of quantum information. In QEC, information is redundantly stored in a large Hilbert space and one or more observables must be monitored to reveal the occurrence of an error, without disturbing the information encoded in an unknown quantum state. Such observables, typically multi-qubit parities such as <XXXX>, must correspond to a special symmetry property inherent to the encoding scheme. Measurements of these observables, or error syndromes, must also be performed in a quantum non-demolition (QND) way and faster than the rate at which errors occur. Previously, QND measurements of quantum jumps between energy eigenstates have been performed in systems such as trapped ions, electrons, cavity quantum electrodynamics (QED), nitrogen-vacancy (NV) centers, and superconducting qubits. So far, however, no fast and repeated monitoring of an error syndrome has been realized. Here, we track the quantum jumps of a possible error syndrome, the photon number parity of a microwave cavity, by mapping this property onto an ancilla qubit. This quantity is just the error syndrome required in a recently proposed scheme for a hardware-efficient protected quantum memory using Schr枚dinger cat states in a harmonic oscillator. We demonstrate the projective nature of this measurement onto a parity eigenspace by observing the collapse of a coherent state onto even or odd cat states. The measurement is fast compared to the cavity lifetime, has a high single-shot fidelity, and has a 99.8% probability per single measurement of leaving the parity unchanged. In combination with the deterministic encoding of quantum information in cat states realized earlier, our demonstrated QND parity tracking represents a significant step towards implementing an active system that extends the lifetime of a quantum bit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1311.2534v1-abstract-full').style.display = 'none'; document.getElementById('1311.2534v1-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, 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">6 pages with 4 figures for the main text, 14 pages with 9 figures for supplementary material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 511, 444-448 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1211.2228">arXiv:1211.2228</a> <span> [<a href="https://arxiv.org/pdf/1211.2228">pdf</a>, <a href="https://arxiv.org/format/1211.2228">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/nature11902">10.1038/nature11902 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of quantum state collapse and revival due to the single-photon Kerr effect </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kirchmair%2C+G">Gerhard Kirchmair</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Zaki Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Nigg%2C+S+E">Simon E. Nigg</a>, <a href="/search/quant-ph?searchtype=author&query=Paik%2C+H">Hanhee Paik</a>, <a href="/search/quant-ph?searchtype=author&query=Ginossar%2C+E">Eran Ginossar</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">Mazyar Mirrahimi</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">Luigi Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Girvin%2C+S+M">S. M. Girvin</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R+J">R. J. Schoelkopf</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="1211.2228v1-abstract-short" style="display: inline;"> Photons are ideal carriers for quantum information as they can have a long coherence time and can be transmitted over long distances. These properties are a consequence of their weak interactions within a nearly linear medium. To create and manipulate nonclassical states of light, however, one requires a strong, nonlinear interaction at the single photon level. One approach to generate suitable in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.2228v1-abstract-full').style.display = 'inline'; document.getElementById('1211.2228v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1211.2228v1-abstract-full" style="display: none;"> Photons are ideal carriers for quantum information as they can have a long coherence time and can be transmitted over long distances. These properties are a consequence of their weak interactions within a nearly linear medium. To create and manipulate nonclassical states of light, however, one requires a strong, nonlinear interaction at the single photon level. One approach to generate suitable interactions is to couple photons to atoms, as in the strong coupling regime of cavity QED systems. In these systems, however, one only indirectly controls the quantum state of the light by manipulating the atoms. A direct photon-photon interaction occurs in so-called Kerr media, which typically induce only weak nonlinearity at the cost of significant loss. So far, it has not been possible to reach the single-photon Kerr regime, where the interaction strength between individual photons exceeds the loss rate. Here, using a 3D circuit QED architecture, we engineer an artificial Kerr medium which enters this regime and allows the observation of new quantum effects. We realize a Gedankenexperiment proposed by Yurke and Stoler, in which the collapse and revival of a coherent state can be observed. This time evolution is a consequence of the quantization of the light field in the cavity and the nonlinear interaction between individual photons. During this evolution non-classical superpositions of coherent states, i.e. multi-component Schroedinger cat states, are formed. We visualize this evolution by measuring the Husimi Q-function and confirm the non-classical properties of these transient states by Wigner tomography. The single-photon Kerr effect could be employed in QND measurement of photons, single photon generation, autonomous quantum feedback schemes and quantum logic operations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1211.2228v1-abstract-full').style.display = 'none'; document.getElementById('1211.2228v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 November, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">6 pages, 4 figures, 5 pages supplementary Material, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 495, 205 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1207.0679">arXiv:1207.0679</a> <span> [<a href="https://arxiv.org/pdf/1207.0679">pdf</a>, <a href="https://arxiv.org/format/1207.0679">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.111.120501">10.1103/PhysRevLett.111.120501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hardware-efficient autonomous quantum error correction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Zaki Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Kirchmair%2C+G">Gerhard Kirchmair</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R">Robert Schoelkopf</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M">Michel Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">Mazyar Mirrahimi</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="1207.0679v2-abstract-short" style="display: inline;"> We propose a new method to autonomously correct for errors of a logical qubit induced by energy relaxation. This scheme encodes the logical qubit as a multi-component superposition of coherent states in a harmonic oscillator, more specifically a cavity mode. The sequences of encoding, decoding and correction operations employ the non-linearity provided by a single physical qubit coupled to the cav… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1207.0679v2-abstract-full').style.display = 'inline'; document.getElementById('1207.0679v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1207.0679v2-abstract-full" style="display: none;"> We propose a new method to autonomously correct for errors of a logical qubit induced by energy relaxation. This scheme encodes the logical qubit as a multi-component superposition of coherent states in a harmonic oscillator, more specifically a cavity mode. The sequences of encoding, decoding and correction operations employ the non-linearity provided by a single physical qubit coupled to the cavity. We layout in detail how to implement these operations in a practical system. This proposal directly addresses the task of building a hardware-efficient and technically realizable quantum memory. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1207.0679v2-abstract-full').style.display = 'none'; document.getElementById('1207.0679v2-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, 2013; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 July, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">12 pages,6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRL 111, 120501 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1205.2401">arXiv:1205.2401</a> <span> [<a href="https://arxiv.org/pdf/1205.2401">pdf</a>, <a href="https://arxiv.org/format/1205.2401">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.87.042315">10.1103/PhysRevA.87.042315 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Deterministic protocol for mapping a qubit to coherent state superpositions in a cavity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Leghtas%2C+Z">Zaki Leghtas</a>, <a href="/search/quant-ph?searchtype=author&query=Kirchmair%2C+G">Gerhard Kirchmair</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M">Michel Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R">Rob Schoelkopf</a>, <a href="/search/quant-ph?searchtype=author&query=Mirrahimi%2C+M">Mazyar Mirrahimi</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="1205.2401v1-abstract-short" style="display: inline;"> We introduce a new gate that transfers an arbitrary state of a qubit into a superposition of two quasi-orthogonal coherent states of a cavity mode, with opposite phases. This qcMAP gate is based on conditional qubit and cavity operations exploiting the energy level dispersive shifts, in the regime where they are much stronger than the cavity and qubit linewidths. The generation of multi-component… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1205.2401v1-abstract-full').style.display = 'inline'; document.getElementById('1205.2401v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1205.2401v1-abstract-full" style="display: none;"> We introduce a new gate that transfers an arbitrary state of a qubit into a superposition of two quasi-orthogonal coherent states of a cavity mode, with opposite phases. This qcMAP gate is based on conditional qubit and cavity operations exploiting the energy level dispersive shifts, in the regime where they are much stronger than the cavity and qubit linewidths. The generation of multi-component superpositions of quasi-orthogonal coherent states, non-local entangled states of two resonators and multi-qubit GHZ states can be efficiently achieved by this gate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1205.2401v1-abstract-full').style.display = 'none'; document.getElementById('1205.2401v1-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 May, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2012. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 87, 042315 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1204.0587">arXiv:1204.0587</a> <span> [<a href="https://arxiv.org/pdf/1204.0587">pdf</a>, <a href="https://arxiv.org/ps/1204.0587">ps</a>, <a href="https://arxiv.org/format/1204.0587">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="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.108.240502">10.1103/PhysRevLett.108.240502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Black-box superconducting circuit quantization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Nigg%2C+S+E">Simon E. Nigg</a>, <a href="/search/quant-ph?searchtype=author&query=Paik%2C+H">Hanhee Paik</a>, <a href="/search/quant-ph?searchtype=author&query=Vlastakis%2C+B">Brian Vlastakis</a>, <a href="/search/quant-ph?searchtype=author&query=Kirchmair%2C+G">Gerhard Kirchmair</a>, <a href="/search/quant-ph?searchtype=author&query=Shankar%2C+S">Shyam Shankar</a>, <a href="/search/quant-ph?searchtype=author&query=Frunzio%2C+L">Luigi Frunzio</a>, <a href="/search/quant-ph?searchtype=author&query=Devoret%2C+M">Michel Devoret</a>, <a href="/search/quant-ph?searchtype=author&query=Schoelkopf%2C+R">Robert Schoelkopf</a>, <a href="/search/quant-ph?searchtype=author&query=Girvin%2C+S">Steven Girvin</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="1204.0587v1-abstract-short" style="display: inline;"> We present a semi-classical method for determining the effective low-energy quantum Hamiltonian of weakly anharmonic superconducting circuits containing mesoscopic Josephson junctions coupled to electromagnetic environments made of an arbitrary combination of distributed and lumped elements. A convenient basis, capturing the multi-mode physics, is given by the quantized eigenmodes of the linearize… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1204.0587v1-abstract-full').style.display = 'inline'; document.getElementById('1204.0587v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1204.0587v1-abstract-full" style="display: none;"> We present a semi-classical method for determining the effective low-energy quantum Hamiltonian of weakly anharmonic superconducting circuits containing mesoscopic Josephson junctions coupled to electromagnetic environments made of an arbitrary combination of distributed and lumped elements. A convenient basis, capturing the multi-mode physics, is given by the quantized eigenmodes of the linearized circuit and is fully determined by a classical linear response function. The method is used to calculate numerically the low-energy spectrum of a 3D-transmon system, and quantitative agreement with measurements is found. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1204.0587v1-abstract-full').style.display = 'none'; document.getElementById('1204.0587v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 April, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">10 pages, 6 figures, includes 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. 108, 240502 (2012) </p> </li> </ol> <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 class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg> <a href="https://info.arxiv.org/help/contact.html"> Contact</a> </li> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>subscribe to arXiv mailings</title><desc>Click here to subscribe</desc><path d="M476 3.2L12.5 270.6c-18.1 10.4-15.8 35.6 2.2 43.2L121 358.4l287.3-253.2c5.5-4.9 13.3 2.6 8.6 8.3L176 407v80.5c0 23.6 28.5 32.9 42.5 15.8L282 426l124.6 52.2c14.2 6 30.4-2.9 33-18.2l72-432C515 7.8 493.3-6.8 476 3.2z"/></svg> <a href="https://info.arxiv.org/help/subscribe"> Subscribe</a> </li> </ul> </div> </div> </div>   <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/license/index.html">Copyright</a></li> <li><a href="https://info.arxiv.org/help/policies/privacy_policy.html">Privacy Policy</a></li> </ul> </div> <div class="column sorry-app-links"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/web_accessibility.html">Web Accessibility Assistance</a></li> <li> <p class="help"> <a class="a11y-main-link" href="https://status.arxiv.org" target="_blank">arXiv Operational Status <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" class="icon filter-dark_grey" role="presentation"><path d="M224.3 273l-136 136c-9.4 9.4-24.6 9.4-33.9 0l-22.6-22.6c-9.4-9.4-9.4-24.6 0-33.9l96.4-96.4-96.4-96.4c-9.4-9.4-9.4-24.6 0-33.9L54.3 103c9.4-9.4 24.6-9.4 33.9 0l136 136c9.5 9.4 9.5 24.6.1 34z"/></svg></a><br> Get status notifications via <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/email/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg>email</a> or <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/slack/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" class="icon filter-black" role="presentation"><path d="M94.12 315.1c0 25.9-21.16 47.06-47.06 47.06S0 341 0 315.1c0-25.9 21.16-47.06 47.06-47.06h47.06v47.06zm23.72 0c0-25.9 21.16-47.06 47.06-47.06s47.06 21.16 47.06 47.06v117.84c0 25.9-21.16 47.06-47.06 47.06s-47.06-21.16-47.06-47.06V315.1zm47.06-188.98c-25.9 0-47.06-21.16-47.06-47.06S139 32 164.9 32s47.06 21.16 47.06 47.06v47.06H164.9zm0 23.72c25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06H47.06C21.16 243.96 0 222.8 0 196.9s21.16-47.06 47.06-47.06H164.9zm188.98 47.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06h-47.06V196.9zm-23.72 0c0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06V79.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06V196.9zM283.1 385.88c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06v-47.06h47.06zm0-23.72c-25.9 0-47.06-21.16-47.06-47.06 0-25.9 21.16-47.06 47.06-47.06h117.84c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06H283.1z"/></svg>slack</a> </p> </li> </ul> </div> </div> </div>  </div> </footer> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/member_acknowledgement.js"></script> </body> </html>

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