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<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=Chen%2C+L&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Chen%2C+L&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Chen%2C+L&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Chen%2C+L&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Chen%2C+L&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> <li> <a href="/search/?searchtype=author&query=Chen%2C+L&start=200" class="pagination-link " aria-label="Page 5" aria-current="page">5 </a> </li> <li><span class="pagination-ellipsis">…</span></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/2502.20199">arXiv:2502.20199</a> <span> [<a href="https://arxiv.org/pdf/2502.20199">pdf</a>, <a href="https://arxiv.org/format/2502.20199">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"> Exploring experimental limit of deep quantum signal processing using a trapped-ion simulator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bu%2C+J+-">J. -T. Bu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Lei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Z">Zhan Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jing-Bo Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+W+-">W. -Q. Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+W+-">W. -F. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+B">B. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+H+-">H. -J. Du</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+W+-">W. -J. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">L. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J+-">J. -W. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J+-">J. -C. Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+F">F. Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+M">M. Feng</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="2502.20199v1-abstract-short" style="display: inline;"> Quantum signal processing (QSP), which enables systematic polynomial transformations on quantum data through sequences of qubit rotations, has emerged as a fundamental building block for quantum algorithms and data re-uploading quantum neural networks. While recent experiments have demonstrated the feasibility of shallow QSP circuits, the inherent limitations in scaling QSP to achieve complex tran… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.20199v1-abstract-full').style.display = 'inline'; document.getElementById('2502.20199v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.20199v1-abstract-full" style="display: none;"> Quantum signal processing (QSP), which enables systematic polynomial transformations on quantum data through sequences of qubit rotations, has emerged as a fundamental building block for quantum algorithms and data re-uploading quantum neural networks. While recent experiments have demonstrated the feasibility of shallow QSP circuits, the inherent limitations in scaling QSP to achieve complex transformations on quantum hardware remain an open and critical question. Here we report the first experimental realization of deep QSP circuits in a trapped-ion quantum simulator. By manipulating the qubit encoded in a trapped $^{43}\textrm{Ca}^{+}$ ion, we demonstrate high-precision simulation of some prominent functions used in quantum algorithms and machine learning, with circuit depths ranging from 15 to 360 layers and implementation time significantly longer than coherence time of the qubit. Our results reveal a crucial trade-off between the precision of function simulation and the concomitant accumulation of hardware noise, highlighting the importance of striking a balance between circuit depth and accuracy in practical QSP implementation. This work addresses a key gap in understanding the scalability and limitations of QSP-based algorithms on quantum hardware, providing valuable insights for developing quantum algorithms as well as practically realizing quantum singular value transformation and data re-uploading quantum machine learning models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.20199v1-abstract-full').style.display = 'none'; document.getElementById('2502.20199v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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, accepted by Physical Review Applied</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.16006">arXiv:2502.16006</a> <span> [<a href="https://arxiv.org/pdf/2502.16006">pdf</a>, <a href="https://arxiv.org/format/2502.16006">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="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Topological Computation by non-Abelian Braiding in Classical Metamaterials </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liyuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Fuertes%2C+M">Matthew Fuertes</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+B">Bolei Deng</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="2502.16006v1-abstract-short" style="display: inline;"> We propose a realization of the one-dimensional Kitaev topological superconductor in classical mechanical metamaterials. By designing appropriate braiding protocols, we demonstrate that the system's mid-gap vibrational modes, termed classical Majorana zero modes (MZMs), accurately reproduce the braiding statistics predicted by quantum theory. Encoding four MZMs as a classical analog of a qubit, we… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.16006v1-abstract-full').style.display = 'inline'; document.getElementById('2502.16006v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.16006v1-abstract-full" style="display: none;"> We propose a realization of the one-dimensional Kitaev topological superconductor in classical mechanical metamaterials. By designing appropriate braiding protocols, we demonstrate that the system's mid-gap vibrational modes, termed classical Majorana zero modes (MZMs), accurately reproduce the braiding statistics predicted by quantum theory. Encoding four MZMs as a classical analog of a qubit, we implement all single-qubit Clifford gates through braiding, enabling the simulation of topological quantum computation in a classical system. Furthermore, we establish the system's topological protection by demonstrating its robustness against mechanical defects. This work provides a novel framework for exploring topological quantum computation using classical metamaterials and offers a pathway to realizing stable vibrational systems protected by topology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.16006v1-abstract-full').style.display = 'none'; document.getElementById('2502.16006v1-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, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 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/2502.07468">arXiv:2502.07468</a> <span> [<a href="https://arxiv.org/pdf/2502.07468">pdf</a>, <a href="https://arxiv.org/format/2502.07468">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Scrambling Enabled Entropy Accumulation in Open Quantum Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yuke Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zeyu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Langxuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+P">Pengfei Zhang</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="2502.07468v1-abstract-short" style="display: inline;"> In closed quantum many-body systems, initially localized information spreads throughout the system and becomes highly complex. This phenomenon, known as information scrambling, is closely related to entropy growth and quantum thermalization. Recent studies have shown that dissipation in open systems can hinder information scrambling, driving the system into a dissipative phase when the system-bath… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.07468v1-abstract-full').style.display = 'inline'; document.getElementById('2502.07468v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.07468v1-abstract-full" style="display: none;"> In closed quantum many-body systems, initially localized information spreads throughout the system and becomes highly complex. This phenomenon, known as information scrambling, is closely related to entropy growth and quantum thermalization. Recent studies have shown that dissipation in open systems can hinder information scrambling, driving the system into a dissipative phase when the system-bath coupling is strong. However, the signature of this scrambling transition in entropy dynamics remains unexplored. In this work, we unveil a novel phenomenon in open quantum systems, termed entropy accumulation, which occurs exclusively within the scrambling phase. We consider a setup in which a probe is weakly coupled to a system that is already interacting with a bath. We calculate the increase in the second R茅nyi entropy induced by an external impulse on the system, after tracing out the probe. Despite the system-probe coupling being weak, the entropy continues to increase and eventually saturates at a finite value due to operator growth. In contrast, the entropy increase is limited by the coupling strength in the dissipative phase. The theoretical prediction is derived from both general arguments and an explicit example using generalized Boltzmann equations. Our results offer new insights into the intriguing relationship between entropy dynamics and information scrambling in open quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.07468v1-abstract-full').style.display = 'none'; document.getElementById('2502.07468v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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, 2 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/2502.06411">arXiv:2502.06411</a> <span> [<a href="https://arxiv.org/pdf/2502.06411">pdf</a>, <a href="https://arxiv.org/format/2502.06411">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="General Relativity and Quantum Cosmology">gr-qc</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</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"> The reliable quantum master equation of the Unruh-DeWitt detector </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Han%2C+S">Si-Wei Han</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+W">Wenjing Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Langxuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ouyang%2C+Z">Zhichun Ouyang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+J">Jun Feng</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="2502.06411v1-abstract-short" style="display: inline;"> In this paper, we present a method for estimating the validity range of the quantum Markovian master equation as applied to the Unruh-DeWitt (UDW) detector within a broader context, particularly without necessitating an exact solution for the detector's evolution. We propose a relaxed van Hove limit (i.e., late-time limit) and offer a perturbative estimate of the error order resulting from the sta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.06411v1-abstract-full').style.display = 'inline'; document.getElementById('2502.06411v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.06411v1-abstract-full" style="display: none;"> In this paper, we present a method for estimating the validity range of the quantum Markovian master equation as applied to the Unruh-DeWitt (UDW) detector within a broader context, particularly without necessitating an exact solution for the detector's evolution. We propose a relaxed van Hove limit (i.e., late-time limit) and offer a perturbative estimate of the error order resulting from the standard derivation procedure of open quantum dynamics. Our primary findings include reliability criteria for the Markov approximation and conditions for the applicability of the rotating wave approximation (RWA). Nevertheless, the specific forms of these validity conditions rely on the details of the detector-field system, such as the spacetime background, the trajectory of the detector, and the type of quantum field being analyzed. Finally, we illustrate our results by re-examining the open dynamics of an accelerating UDW detector undergoing the Unruh effect, where the validity conditions narrow the parameter space to ensure the solution's reliability regarding the quantum Markovian master equation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.06411v1-abstract-full').style.display = 'none'; document.getElementById('2502.06411v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 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/2502.02855">arXiv:2502.02855</a> <span> [<a href="https://arxiv.org/pdf/2502.02855">pdf</a>, <a href="https://arxiv.org/ps/2502.02855">ps</a>, <a href="https://arxiv.org/format/2502.02855">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"> Holevo Cram茅r-Rao bound for multi-parameter estimation in nonlinear interferometers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+M">Mengyao Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+H">Hongmei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liqing Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weiping Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chun-Hua Yuan</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="2502.02855v1-abstract-short" style="display: inline;"> Due to the potential of quantum advantage to surpass the standard quantum limit (SQL), the nonlinear interferometers have garnered significant attention from researchers in the field of precision measurement. However, many practical applications require multi-parameter estimation. In this work, we discuss the precision limit of multi-parameter estimation of pure Gaussian states based on nonlinear… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.02855v1-abstract-full').style.display = 'inline'; document.getElementById('2502.02855v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.02855v1-abstract-full" style="display: none;"> Due to the potential of quantum advantage to surpass the standard quantum limit (SQL), the nonlinear interferometers have garnered significant attention from researchers in the field of precision measurement. However, many practical applications require multi-parameter estimation. In this work, we discuss the precision limit of multi-parameter estimation of pure Gaussian states based on nonlinear interferometers, and derive the Holevo Cram茅r-Rao Bound (HCRB) for the case where both modes undergo displacement estimation. Furthermore, we compare our analytical results with the quantum Cram茅r-Rao Bound based on the symmetric logarithmic derivative (SLD-CRB), and with the result of the dual homodyne measurement. Through numerical analysis, we find that the HCRB equals the result of the dual homodyne measurement, whereas SLD-CRB is not saturable at small squeezed parameters. Therefore, this indicates that the HCRB is tight. Additionally, we provide intuitive analysis and visual representation of our numerical results in phase space. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.02855v1-abstract-full').style.display = 'none'; document.getElementById('2502.02855v1-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </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, 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/2501.04327">arXiv:2501.04327</a> <span> [<a href="https://arxiv.org/pdf/2501.04327">pdf</a>, <a href="https://arxiv.org/format/2501.04327">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"> Machine Learning Enhanced Quantum State Tomography on FPGA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hsun-Chung Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Hsieh%2C+H">Hsien-Yi Hsieh</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zhi-Kai Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H+L">Hua Li Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+Z">Zi-Hao Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Po-Han Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+P">Popo Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Steuernagel%2C+O">Ole Steuernagel</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+C">Chien-Ming Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+R">Ray-Kuang Lee</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="2501.04327v1-abstract-short" style="display: inline;"> Machine learning techniques have opened new avenues for real-time quantum state tomography (QST). In this work, we demonstrate the deployment of machine learning-based QST onto edge devices, specifically utilizing field programmable gate arrays (FPGAs). This implementation is realized using the {\it Vitis AI Integrated Development Environment} provided by AMD\textsuperscript \textregistered~Inc. C… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.04327v1-abstract-full').style.display = 'inline'; document.getElementById('2501.04327v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.04327v1-abstract-full" style="display: none;"> Machine learning techniques have opened new avenues for real-time quantum state tomography (QST). In this work, we demonstrate the deployment of machine learning-based QST onto edge devices, specifically utilizing field programmable gate arrays (FPGAs). This implementation is realized using the {\it Vitis AI Integrated Development Environment} provided by AMD\textsuperscript \textregistered~Inc. Compared to the Graphics Processing Unit (GPU)-based machine learning QST, our FPGA-based one reduces the average inference time by an order of magnitude, from 38 ms to 2.94 ms, but only sacrifices the average fidelity about $1\% $ reduction (from 0.99 to 0.98). The FPGA-based QST offers a highly efficient and precise tool for diagnosing quantum states, marking a significant advancement in the practical applications for quantum information processing and quantum sensing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.04327v1-abstract-full').style.display = 'none'; document.getElementById('2501.04327v1-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, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </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, 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/2501.03123">arXiv:2501.03123</a> <span> [<a href="https://arxiv.org/pdf/2501.03123">pdf</a>, <a href="https://arxiv.org/format/2501.03123">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="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Crypto-nonlocality in arbitrarily dimensional systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sheng%2C+J">Jianqi Sheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+D">Dongkai Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lixiang Chen</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="2501.03123v1-abstract-short" style="display: inline;"> According to Bell's theorem, any model based on local variables cannot reproduce certain quantum correlations. A critical question is whether one could devise an alternative framework, based on nonlocal variables, to reproduce quantum correlations while adhering to fundamental principles. Leggett proposed a nonlocal model, termed crypto-nonlocality, rooted in considerations of the reality of photo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.03123v1-abstract-full').style.display = 'inline'; document.getElementById('2501.03123v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.03123v1-abstract-full" style="display: none;"> According to Bell's theorem, any model based on local variables cannot reproduce certain quantum correlations. A critical question is whether one could devise an alternative framework, based on nonlocal variables, to reproduce quantum correlations while adhering to fundamental principles. Leggett proposed a nonlocal model, termed crypto-nonlocality, rooted in considerations of the reality of photon polarization, but this property restricted it to being bi-dimensional. In this Letter, we extend the crypto-nonlocal model to higher dimensions and develop a framework for constructing experimentally testable Leggett-type inequalities for arbitrary dimensions. Our investigation into models that yield specific predictions exceeding those of quantum mechanics is intriguing from an information-theoretic perspective and is expected to deepen our understanding of quantum correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.03123v1-abstract-full').style.display = 'none'; document.getElementById('2501.03123v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to PRA</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.03109">arXiv:2501.03109</a> <span> [<a href="https://arxiv.org/pdf/2501.03109">pdf</a>, <a href="https://arxiv.org/format/2501.03109">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="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Orbital Angular Momentum Experimental Bound on the Maximum Predictive Power of Physical Theories in Multi-Dimensional Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sheng%2C+J">Jianqi Sheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+D">Dongkai Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lixiang Chen</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="2501.03109v1-abstract-short" style="display: inline;"> The completeness of quantum mechanics in predictive power is a central question in its foundational study. While most investigations focus on two-dimensional systems, high-dimensional systems are more general and widely applicable. Building on the non-extensibility theorem by Colbeck and Renner [Phys. Rev. Lett. 101, 050403 (2008)], which established that no higher theory can enhance the predictiv… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.03109v1-abstract-full').style.display = 'inline'; document.getElementById('2501.03109v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.03109v1-abstract-full" style="display: none;"> The completeness of quantum mechanics in predictive power is a central question in its foundational study. While most investigations focus on two-dimensional systems, high-dimensional systems are more general and widely applicable. Building on the non-extensibility theorem by Colbeck and Renner [Phys. Rev. Lett. 101, 050403 (2008)], which established that no higher theory can enhance the predictive power of quantum mechanics for two-dimensional systems, we extend this result to arbitrarily dimensional systems. We connect maximum potential predictive power achievable by any alternative theory to experimentally observable correlations, and establish optimal experimental bounds across varying dimensions by exploiting two-photon orbital angular momentum entangled states with entanglement concentration. These bounds falsify a broader class of alternative theories, including Bell's and Leggett's models, and those that remain theoretically ambiguous or experimentally unverified. Our findings not only deepen the foundational understanding of quantum mechanics but also hold significant potential for high-dimensional quantum cryptography. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.03109v1-abstract-full').style.display = 'none'; document.getElementById('2501.03109v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to PRX Quantum</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.02764">arXiv:2501.02764</a> <span> [<a href="https://arxiv.org/pdf/2501.02764">pdf</a>, <a href="https://arxiv.org/ps/2501.02764">ps</a>, <a href="https://arxiv.org/format/2501.02764">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</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"> Floquet geometric squeezing in fast-rotating condensates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Li Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+F">Fei Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yunbo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pu%2C+H">Han Pu</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="2501.02764v1-abstract-short" style="display: inline;"> Constructing and manipulating quantum states in fast-rotating Bose-Einstein condensates (BEC) has long stood as a significant challenge as the rotating speed approaching the critical velocity. Although the recent experiment [Science, 372, 1318 (2021)] has realized the geometrically squeezed state of the guiding-center mode, the remaining degree of freedom, the cyclotron mode, remains unsqueezed du… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.02764v1-abstract-full').style.display = 'inline'; document.getElementById('2501.02764v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.02764v1-abstract-full" style="display: none;"> Constructing and manipulating quantum states in fast-rotating Bose-Einstein condensates (BEC) has long stood as a significant challenge as the rotating speed approaching the critical velocity. Although the recent experiment [Science, 372, 1318 (2021)] has realized the geometrically squeezed state of the guiding-center mode, the remaining degree of freedom, the cyclotron mode, remains unsqueezed due to the large energy gap of Landau levels. To overcome this limitation, in this paper, we propose a Floquet-based state-preparation protocol by periodically driving an anisotropic potential. This protocol not only facilitates the single cyclotron-mode squeezing, but also enables a two-mode squeezing. Such two-mode squeezing offers a richer set of dynamics compared to single-mode squeezing and can achieve wavepacket width well below the lowest Landau level limit. Our work provides a highly controllable knob for realizing diverse geometrically squeezed states in ultracold quantum gases within the quantum Hall regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.02764v1-abstract-full').style.display = 'none'; document.getElementById('2501.02764v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </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 + 6 pages, 4 figures, 7 animations. To appear as a Letter in PRA</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.19019">arXiv:2412.19019</a> <span> [<a href="https://arxiv.org/pdf/2412.19019">pdf</a>, <a href="https://arxiv.org/format/2412.19019">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"> Harnessing high-dimensional symmetric and anti-symmetric Bell states through quantum interference </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hong%2C+L">Ling Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yuning Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yuanyuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lixiang Chen</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="2412.19019v1-abstract-short" style="display: inline;"> High-dimensional quantum entanglement is an essential resource in quantum technology since it provides benefits in increasing the information capacity and processing speed. Thus, the controlled harnessing of high-dimensional entanglement has long been hailed as a necessary prerequisite towards practical quantum applications. By using a deterministic quantum state filter that implemented through qu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.19019v1-abstract-full').style.display = 'inline'; document.getElementById('2412.19019v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.19019v1-abstract-full" style="display: none;"> High-dimensional quantum entanglement is an essential resource in quantum technology since it provides benefits in increasing the information capacity and processing speed. Thus, the controlled harnessing of high-dimensional entanglement has long been hailed as a necessary prerequisite towards practical quantum applications. By using a deterministic quantum state filter that implemented through quantum interference, we present a generalised formulation for the complete high-dimensional symmetric and anti-symmetric Bell basis, and experimentally prepare four-dimensional orbital angular momentum Bell states that provide the well-behaved symmetric or anti-symmetric properties. Additionally, we use a concise yet efficient scan of temporal delay to directly observe high-dimensional two-photon interference effects in spatial modes. These results provide an alternative way for harnessing high-dimensional entanglement, and may facilitate the use of quantum interference for more complex quantum information processing tasks that beyond qubits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.19019v1-abstract-full').style.display = 'none'; document.getElementById('2412.19019v1-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Under Review</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.15022">arXiv:2412.15022</a> <span> [<a href="https://arxiv.org/pdf/2412.15022">pdf</a>, <a href="https://arxiv.org/ps/2412.15022">ps</a>, <a href="https://arxiv.org/format/2412.15022">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum SWAP gate realized with CZ and iSWAP gates in a superconducting architecture </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kri%C5%BEan%2C+C">Christian Kri啪an</a>, <a href="/search/quant-ph?searchtype=author&query=Bizn%C3%A1rov%C3%A1%2C+J">Janka Bizn谩rov谩</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liangyu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Hogedal%2C+E">Emil Hogedal</a>, <a href="/search/quant-ph?searchtype=author&query=Osman%2C+A">Amr Osman</a>, <a href="/search/quant-ph?searchtype=author&query=Warren%2C+C+W">Christopher W. Warren</a>, <a href="/search/quant-ph?searchtype=author&query=Kosen%2C+S">Sandoko Kosen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hang-Xi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Abad%2C+T">Tahereh Abad</a>, <a href="/search/quant-ph?searchtype=author&query=Aggarwal%2C+A">Anuj Aggarwal</a>, <a href="/search/quant-ph?searchtype=author&query=Caputo%2C+M">Marco Caputo</a>, <a href="/search/quant-ph?searchtype=author&query=Fern%C3%A1ndez-Pend%C3%A1s%2C+J">Jorge Fern谩ndez-Pend谩s</a>, <a href="/search/quant-ph?searchtype=author&query=Gaikwad%2C+A">Akshay Gaikwad</a>, <a href="/search/quant-ph?searchtype=author&query=Gr%C3%B6nberg%2C+L">Leif Gr枚nberg</a>, <a href="/search/quant-ph?searchtype=author&query=Nylander%2C+A">Andreas Nylander</a>, <a href="/search/quant-ph?searchtype=author&query=Rehammar%2C+R">Robert Rehammar</a>, <a href="/search/quant-ph?searchtype=author&query=Rommel%2C+M">Marcus Rommel</a>, <a href="/search/quant-ph?searchtype=author&query=Yuzephovich%2C+O+I">Olga I. Yuzephovich</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a>, <a href="/search/quant-ph?searchtype=author&query=Govenius%2C+J">Joonas Govenius</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">Giovanna Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Bylander%2C+J">Jonas Bylander</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.15022v1-abstract-short" style="display: inline;"> It is advantageous for any quantum processor to support different classes of two-qubit quantum logic gates when compiling quantum circuits, a property that is typically not seen with existing platforms. In particular, access to a gate set that includes support for the CZ-type, the iSWAP-type, and the SWAP-type families of gates, renders conversions between these gate families unnecessary during co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.15022v1-abstract-full').style.display = 'inline'; document.getElementById('2412.15022v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.15022v1-abstract-full" style="display: none;"> It is advantageous for any quantum processor to support different classes of two-qubit quantum logic gates when compiling quantum circuits, a property that is typically not seen with existing platforms. In particular, access to a gate set that includes support for the CZ-type, the iSWAP-type, and the SWAP-type families of gates, renders conversions between these gate families unnecessary during compilation as any two-qubit Clifford gate can be executed using at most one two-qubit gate from this set, plus additional single-qubit gates. We experimentally demonstrate that a SWAP gate can be decomposed into one iSWAP gate followed by one CZ gate, affirming a more efficient compilation strategy over the conventional approach that relies on three iSWAP or three CZ gates to replace a SWAP gate. Our implementation makes use of a superconducting quantum processor design based on fixed-frequency transmon qubits coupled together by a parametrically modulated tunable transmon coupler, extending this platform's native gate set so that any two-qubit Clifford unitary matrix can be realized using no more than two two-qubit gates and single-qubit gates. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.15022v1-abstract-full').style.display = 'none'; document.getElementById('2412.15022v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">29 pages, 13 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/2412.03802">arXiv:2412.03802</a> <span> [<a href="https://arxiv.org/pdf/2412.03802">pdf</a>, <a href="https://arxiv.org/format/2412.03802">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="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> On-Chip Enhanced Biphoton Generation with Incoherent Light </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yue-Wei Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+H">Heng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Li Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yin-Hai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wu-Zhen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+M">Ming-Yuan Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+R">Ren-Hui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zhao-Qi-Zhi Han</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+M">Meng-Yu Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zhi-Yuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</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="2412.03802v1-abstract-short" style="display: inline;"> On-chip quantum photon sources are pivotal components in integrated photonics, driving significant advancements in quantum information technologies over recent decades. Traditionally, the coherence of the pump beam has been considered a critical property in ensuring the quality of the source. In this work, we produce a photon-pair source via spontaneous four-wave mixing pumped by temporally incohe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03802v1-abstract-full').style.display = 'inline'; document.getElementById('2412.03802v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.03802v1-abstract-full" style="display: none;"> On-chip quantum photon sources are pivotal components in integrated photonics, driving significant advancements in quantum information technologies over recent decades. Traditionally, the coherence of the pump beam has been considered a critical property in ensuring the quality of the source. In this work, we produce a photon-pair source via spontaneous four-wave mixing pumped by temporally incoherent light in a standard silicon nanowire. Compared to a coherent laser, the incoherence improves pump utilization efficiency, which results in higher source brightness. Additionally, its spectrally uncorrelated nature of incoherent light is transferred to the generated photon source, allowing high-purity state preparation without the need for narrow filtering. Experimentally, we demonstrate the advantages using an amplified spontaneous emission source over a continuous-wave laser. With temporally incoherent pumping, the photon pair generation rate increases by 40%. The coincidence-to-accidental ratio and heralded second-order autocorrelation exhibit improved performance at low power. Our work expands the scope of incoherently pumped quantum states and provides a method for generating photon sources using a more readily accessible light. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03802v1-abstract-full').style.display = 'none'; document.getElementById('2412.03802v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.03022">arXiv:2412.03022</a> <span> [<a href="https://arxiv.org/pdf/2412.03022">pdf</a>, <a href="https://arxiv.org/format/2412.03022">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.133.233601">10.1103/PhysRevLett.133.233601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Entangling independent particles by path identity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+K">Kai Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+Z">Zhaohua Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+K">Kaiyi Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Leizhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Krenn%2C+M">Mario Krenn</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+S">Shining Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiao-song Ma</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="2412.03022v1-abstract-short" style="display: inline;"> Quantum entanglement -- correlations of particles that are stronger than any classical analogue -- is the basis for research on the foundations of quantum mechanics and for practical applications such as quantum networks. Traditionally, entanglement is achieved through local interactions or via entanglement swapping, where entanglement at a distance is generated through previously established enta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03022v1-abstract-full').style.display = 'inline'; document.getElementById('2412.03022v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.03022v1-abstract-full" style="display: none;"> Quantum entanglement -- correlations of particles that are stronger than any classical analogue -- is the basis for research on the foundations of quantum mechanics and for practical applications such as quantum networks. Traditionally, entanglement is achieved through local interactions or via entanglement swapping, where entanglement at a distance is generated through previously established entanglement and Bell-state measurements. However, the precise requirements enabling the generation of quantum entanglement without traditional local interactions remain less explored. Here we demonstrate that independent particles can be entangled without the need for direct interaction, prior established entanglement, or Bell-state measurements, by exploiting the indistinguishability of the origins of photon pairs. Our demonstrations challenge the long-standing belief that the prior generation and measurement of entanglement are necessary prerequisites for generating entanglement between independent particles that do not share a common past. In addition to its foundational interest, we show that this technique might lower the resource requirements in quantum networks, by reducing the complexity of photon sources and the overhead photon numbers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.03022v1-abstract-full').style.display = 'none'; document.getElementById('2412.03022v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 133, 233601 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.01334">arXiv:2412.01334</a> <span> [<a href="https://arxiv.org/pdf/2412.01334">pdf</a>, <a href="https://arxiv.org/ps/2412.01334">ps</a>, <a href="https://arxiv.org/format/2412.01334">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"> Order-six CHMs containing exactly three distinct elements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yanzu Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+M">Mengfan Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</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="2412.01334v1-abstract-short" style="display: inline;"> Complex Hadamard matrices (CHMs) are intimately related to the number of distinct matrix elements. We investigate CHMs containing exactly three distinct elements, which is also the least number of distinct elements. In this paper, we show that such CHMs can only be complex equivalent to two kind of matrices, one is $H_2$-reducible and the other is the Tao matrix. Using our result one can further n… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.01334v1-abstract-full').style.display = 'inline'; document.getElementById('2412.01334v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.01334v1-abstract-full" style="display: none;"> Complex Hadamard matrices (CHMs) are intimately related to the number of distinct matrix elements. We investigate CHMs containing exactly three distinct elements, which is also the least number of distinct elements. In this paper, we show that such CHMs can only be complex equivalent to two kind of matrices, one is $H_2$-reducible and the other is the Tao matrix. Using our result one can further narrow the range of MUB trio (a set of four MUBs in $\mathbb{C}^6$ consists of an MUB trio and the identity) since we find that the two CHMs neither belong to MUB trios. Our results may lead to the more complete classification of $6\times 6$ CHMs whose elements in the first row are all 1. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.01334v1-abstract-full').style.display = 'none'; document.getElementById('2412.01334v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">29 pages, 0 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/2411.12518">arXiv:2411.12518</a> <span> [<a href="https://arxiv.org/pdf/2411.12518">pdf</a>, <a href="https://arxiv.org/format/2411.12518">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Popular Physics">physics.pop-ph</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"> Quantum state tomography with muons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gao%2C+L">Leyun Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Ruzi%2C+A">Alim Ruzi</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qite Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+C">Chen Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liangwen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xueheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Z">Zhiyu Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qiang Li</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="2411.12518v1-abstract-short" style="display: inline;"> Entanglement is a fundamental pillar of quantum mechanics. Probing quantum entanglement and testing Bell inequality with muons can be a significant leap forward, as muon is arguably the only massive elementary particle that can be manipulated and detected over a wide range of energies, e.g., from approximately 0.3 to $10^2$ GeV, corresponding to velocities from 0.94 to nearly the speed of light. I… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.12518v1-abstract-full').style.display = 'inline'; document.getElementById('2411.12518v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.12518v1-abstract-full" style="display: none;"> Entanglement is a fundamental pillar of quantum mechanics. Probing quantum entanglement and testing Bell inequality with muons can be a significant leap forward, as muon is arguably the only massive elementary particle that can be manipulated and detected over a wide range of energies, e.g., from approximately 0.3 to $10^2$ GeV, corresponding to velocities from 0.94 to nearly the speed of light. In this work, we present a realistic proposal and a comprehensive study of quantum entanglement in a state composed of different-flavor fermions in muon-electron scattering. The polarization density matrix for the muon-electron system is derived using a kinematic approach within the relativistic quantum field theory framework. Entanglement in the resulting muon-electron qubit system and the violation of Bell inequalities can be observed with a high event rate. This paves the way for performing quantum tomography with muons. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.12518v1-abstract-full').style.display = 'none'; document.getElementById('2411.12518v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures; Probing and Knocking with Muon (PKMu) Experiment Proposal Series 3 for Quantum</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.10396">arXiv:2411.10396</a> <span> [<a href="https://arxiv.org/pdf/2411.10396">pdf</a>, <a href="https://arxiv.org/format/2411.10396">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"> Implementation of scalable suspended superinductors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=J%C3%BCnger%2C+C">Christian J眉nger</a>, <a href="/search/quant-ph?searchtype=author&query=Chistolini%2C+T">Trevor Chistolini</a>, <a href="/search/quant-ph?searchtype=author&query=Nguyen%2C+L+B">Long B. Nguyen</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+H">Hyunseong Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Larry Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ersevim%2C+T">Thomas Ersevim</a>, <a href="/search/quant-ph?searchtype=author&query=Livingston%2C+W">William Livingston</a>, <a href="/search/quant-ph?searchtype=author&query=Koolstra%2C+G">Gerwin Koolstra</a>, <a href="/search/quant-ph?searchtype=author&query=Santiago%2C+D+I">David I. Santiago</a>, <a href="/search/quant-ph?searchtype=author&query=Siddiqi%2C+I">Irfan Siddiqi</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="2411.10396v1-abstract-short" style="display: inline;"> Superinductors have become a crucial component in the superconducting circuit toolbox, playing a key role in the development of more robust qubits. Enhancing the performance of these devices can be achieved by suspending the superinductors from the substrate, thereby reducing stray capacitance. Here, we present a fabrication framework for constructing superconducting circuits with suspended superi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.10396v1-abstract-full').style.display = 'inline'; document.getElementById('2411.10396v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.10396v1-abstract-full" style="display: none;"> Superinductors have become a crucial component in the superconducting circuit toolbox, playing a key role in the development of more robust qubits. Enhancing the performance of these devices can be achieved by suspending the superinductors from the substrate, thereby reducing stray capacitance. Here, we present a fabrication framework for constructing superconducting circuits with suspended superinductors in planar architectures. To validate the effectiveness of this process, we systematically characterize both resonators and qubits with suspended arrays of Josephson junctions, ultimately confirming the high quality of the superinductive elements. In addition, this process is broadly compatible with other types of superinductors and circuit designs. Our results not only pave the way for scalable novel superconducting architectures but also provide the primitive for future investigation of loss mechanisms associated with the device substrate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.10396v1-abstract-full').style.display = 'none'; document.getElementById('2411.10396v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.09697">arXiv:2411.09697</a> <span> [<a href="https://arxiv.org/pdf/2411.09697">pdf</a>, <a href="https://arxiv.org/format/2411.09697">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> A Universal Circuit Set Using the $S_3$ Quantum Double </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liyuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+Y">Yuanjie Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+R">Ruihua Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Jaffe%2C+A">Arthur Jaffe</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="2411.09697v1-abstract-short" style="display: inline;"> One potential route toward fault-tolerant universal quantum computation is to use non-Abelian topological codes. In this work, we investigate how to achieve this goal with the quantum double model $\mathcal{D}(S_3)$ -- a specific non-Abelian topological code. By embedding each on-site Hilbert space into a qubit-qutrit pair, we give an explicit construction of the circuits for creating, moving, and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.09697v1-abstract-full').style.display = 'inline'; document.getElementById('2411.09697v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.09697v1-abstract-full" style="display: none;"> One potential route toward fault-tolerant universal quantum computation is to use non-Abelian topological codes. In this work, we investigate how to achieve this goal with the quantum double model $\mathcal{D}(S_3)$ -- a specific non-Abelian topological code. By embedding each on-site Hilbert space into a qubit-qutrit pair, we give an explicit construction of the circuits for creating, moving, and locally measuring all non-trivial anyons. We also design a specialized anyon interferometer to measure the total charge remotely for well-separated anyons; this avoids fusing them together. These protocols enable the implementation of a universal gate set proposed by Cui et al. and active quantum error correction of the circuit-level noise during the computation process. To further reduce the error rate and facilitate error correction, we encode each physical degree of freedom of $\mathcal{D}(S_3)$ into a novel, quantum, error-correcting code, enabling fault-tolerant realization, at the logical level, of all gates in the anyon manipulation circuits. Our proposal offers a promising path to realize universal topological quantum computation in the NISQ era. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.09697v1-abstract-full').style.display = 'none'; document.getElementById('2411.09697v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.07886">arXiv:2411.07886</a> <span> [<a href="https://arxiv.org/pdf/2411.07886">pdf</a>, <a href="https://arxiv.org/format/2411.07886">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="Chemical Physics">physics.chem-ph</span> </div> </div> <p class="title is-5 mathjax"> Simulating Quantum Many-Body States with Neural-Network Exponential Ansatz </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+W">Weillei Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jiaji Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lipeng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Benavides-Riveros%2C+C+L">Carlos L. Benavides-Riveros</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="2411.07886v1-abstract-short" style="display: inline;"> Preparing quantum many-body states on classical or quantum devices is a very challenging task that requires accounting for exponentially large Hilbert spaces. Although this complexity can be managed with exponential ans盲tze (such as in the coupled-cluster method), these approaches are often tailored to specific systems, which limits their universality. Recent work has shown that the contracted Sch… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.07886v1-abstract-full').style.display = 'inline'; document.getElementById('2411.07886v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.07886v1-abstract-full" style="display: none;"> Preparing quantum many-body states on classical or quantum devices is a very challenging task that requires accounting for exponentially large Hilbert spaces. Although this complexity can be managed with exponential ans盲tze (such as in the coupled-cluster method), these approaches are often tailored to specific systems, which limits their universality. Recent work has shown that the contracted Schr枚dinger equation enables the construction of universal, formally exact exponential ans盲tze for quantum many-body physics. However, while the ansatz is capable of resolving arbitrary quantum systems, it still requires a full calculation of its parameters whenever the underlying Hamiltonian changes, even slightly. Here, inspired by recent progress in operator learning, we develop a surrogate neural network solver that generates the exponential ansatz parameters using the Hamiltonian parameters as inputs, eliminating the need for repetitive computations. We illustrate the effectiveness of this approach by training neural networks of several quantum many-body systems, including the Fermi-Hubbard model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.07886v1-abstract-full').style.display = 'none'; document.getElementById('2411.07886v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.05501">arXiv:2411.05501</a> <span> [<a href="https://arxiv.org/pdf/2411.05501">pdf</a>, <a href="https://arxiv.org/format/2411.05501">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"> Multifunctional metalens for trapping and characterizing single atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+G">Guang-Jie Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+D">Dong Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhu-Bo Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Ziqin Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Ji-Zhe Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yan-Lei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xin-Biao Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+A">Ai-Ping Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+C">Chun-Hua Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+K">Kun Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+C">Chang-Ling Zou</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="2411.05501v1-abstract-short" style="display: inline;"> Precise control and manipulation of neutral atoms are essential for quantum technologies but largely dependent on conventional bulky optical setups. Here, we demonstrate a multifunctional metalens that integrates an achromatic lens with large numerical aperture, a quarter-wave plate, and a polarizer for trapping and characterizing single Rubidium atoms. The metalens simultaneously focuses a trappi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05501v1-abstract-full').style.display = 'inline'; document.getElementById('2411.05501v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.05501v1-abstract-full" style="display: none;"> Precise control and manipulation of neutral atoms are essential for quantum technologies but largely dependent on conventional bulky optical setups. Here, we demonstrate a multifunctional metalens that integrates an achromatic lens with large numerical aperture, a quarter-wave plate, and a polarizer for trapping and characterizing single Rubidium atoms. The metalens simultaneously focuses a trapping beam at 852\,nm and collects single-photon fluorescence at 780\,nm. We observe a strong dependence of the trapping lifetime on an external bias magnetic field, suggests a complex interplay between the circularly polarized trapping light and the atom's internal states. Our work showcases the potential of metasurfaces in realizing compact and integrated quantum systems based on cold atoms, opening up new possibilities for studying quantum control and manipulation at the nanoscale. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05501v1-abstract-full').style.display = 'none'; document.getElementById('2411.05501v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 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/2411.05364">arXiv:2411.05364</a> <span> [<a href="https://arxiv.org/pdf/2411.05364">pdf</a>, <a href="https://arxiv.org/format/2411.05364">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Strong-to-weak Symmetry Breaking and Entanglement Transitions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Langxuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+N">Ning Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+P">Pengfei Zhang</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="2411.05364v1-abstract-short" style="display: inline;"> When interacting with an environment, the entanglement within quantum many-body systems is rapidly transferred to the entanglement between the system and the bath. For systems with a large local Hilbert space dimension, this leads to a first-order entanglement transition for the reduced density matrix of the system. On the other hand, recent studies have introduced a new paradigm for classifying d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05364v1-abstract-full').style.display = 'inline'; document.getElementById('2411.05364v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.05364v1-abstract-full" style="display: none;"> When interacting with an environment, the entanglement within quantum many-body systems is rapidly transferred to the entanglement between the system and the bath. For systems with a large local Hilbert space dimension, this leads to a first-order entanglement transition for the reduced density matrix of the system. On the other hand, recent studies have introduced a new paradigm for classifying density matrices, with particular focus on scenarios where a strongly symmetric density matrix undergoes spontaneous symmetry breaking to a weak symmetry phase. This is typically characterized by a finite R茅nyi-2 correlator or a finite Wightman correlator. In this work, we study the entanglement transition from the perspective of strong-to-weak symmetry breaking, using solvable complex Brownian SYK models. We perform analytical calculations for both the early-time and late-time saddles. The results show that while the R茅nyi-2 correlator indicates a transition from symmetric to symmetry-broken phase, the Wightman correlator becomes finite even in the early-time saddle due to the single-replica limit, demonstrating that the first-order transition occurs between a near-symmetric phase and a deeply symmetry-broken phase in the sense of Wightman correlator. Our results provide a novel viewpoint on the entanglement transition under symmetry constraints and can be readily generalized to systems with repeated measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.05364v1-abstract-full').style.display = 'none'; document.getElementById('2411.05364v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 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/2411.04978">arXiv:2411.04978</a> <span> [<a href="https://arxiv.org/pdf/2411.04978">pdf</a>, <a href="https://arxiv.org/format/2411.04978">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</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"> Holographic pseudoentanglement and the complexity of the AdS/CFT dictionary </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Akers%2C+C">Chris Akers</a>, <a href="/search/quant-ph?searchtype=author&query=Bouland%2C+A">Adam Bouland</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lijie Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Kohler%2C+T">Tamara Kohler</a>, <a href="/search/quant-ph?searchtype=author&query=Metger%2C+T">Tony Metger</a>, <a href="/search/quant-ph?searchtype=author&query=Vazirani%2C+U">Umesh Vazirani</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="2411.04978v1-abstract-short" style="display: inline;"> The `quantum gravity in the lab' paradigm suggests that quantum computers might shed light on quantum gravity by simulating the CFT side of the AdS/CFT correspondence and mapping the results to the AdS side. This relies on the assumption that the duality map (the `dictionary') is efficient to compute. In this work, we show that the complexity of the AdS/CFT dictionary is surprisingly subtle: there… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.04978v1-abstract-full').style.display = 'inline'; document.getElementById('2411.04978v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.04978v1-abstract-full" style="display: none;"> The `quantum gravity in the lab' paradigm suggests that quantum computers might shed light on quantum gravity by simulating the CFT side of the AdS/CFT correspondence and mapping the results to the AdS side. This relies on the assumption that the duality map (the `dictionary') is efficient to compute. In this work, we show that the complexity of the AdS/CFT dictionary is surprisingly subtle: there might be cases in which one can efficiently apply operators to the CFT state (a task we call 'operator reconstruction') without being able to extract basic properties of the dual bulk state such as its geometry (which we call 'geometry reconstruction'). Geometry reconstruction corresponds to the setting where we want to extract properties of a completely unknown bulk dual from a simulated CFT boundary state. We demonstrate that geometry reconstruction may be generically hard due to the connection between geometry and entanglement in holography. In particular we construct ensembles of states whose entanglement approximately obey the Ryu-Takayanagi formula for arbitrary geometries, but which are nevertheless computationally indistinguishable. This suggests that even for states with the special entanglement structure of holographic CFT states, geometry reconstruction might be hard. This result should be compared with existing evidence that operator reconstruction is generically easy in AdS/CFT. A useful analogy for the difference between these two tasks is quantum fully homomorphic encryption (FHE): this encrypts quantum states in such a way that no efficient adversary can learn properties of the state, but operators can be applied efficiently to the encrypted state. We show that quantum FHE can separate the complexity of geometry reconstruction vs operator reconstruction, which raises the question whether FHE could be a useful lens through which to view AdS/CFT. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.04978v1-abstract-full').style.display = 'none'; document.getElementById('2411.04978v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">45 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/2411.04442">arXiv:2411.04442</a> <span> [<a href="https://arxiv.org/pdf/2411.04442">pdf</a>, <a href="https://arxiv.org/format/2411.04442">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"> Benchmarking Single-Qubit Gates on a Noise-Biased Qubit Beyond the Fault-Tolerant Threshold </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qing%2C+B">Bingcheng Qing</a>, <a href="/search/quant-ph?searchtype=author&query=Hajr%2C+A">Ahmed Hajr</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+K">Ke Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Koolstra%2C+G">Gerwin Koolstra</a>, <a href="/search/quant-ph?searchtype=author&query=Nguyen%2C+L+B">Long B. Nguyen</a>, <a href="/search/quant-ph?searchtype=author&query=Hines%2C+J">Jordan Hines</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+I">Irwin Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Bhandari%2C+B">Bibek Bhandari</a>, <a href="/search/quant-ph?searchtype=author&query=Padramrazi%2C+Z">Zahra Padramrazi</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Larry Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Kang%2C+Z">Ziqi Kang</a>, <a href="/search/quant-ph?searchtype=author&query=J%C3%BCnger%2C+C">Christian J眉nger</a>, <a href="/search/quant-ph?searchtype=author&query=Goss%2C+N">Noah Goss</a>, <a href="/search/quant-ph?searchtype=author&query=Jain%2C+N">Nikitha Jain</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+H">Hyunseong Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+K">Kan-Heng Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Hashim%2C+A">Akel Hashim</a>, <a href="/search/quant-ph?searchtype=author&query=Frattini%2C+N+E">Nicholas E. Frattini</a>, <a href="/search/quant-ph?searchtype=author&query=Dressel%2C+J">Justin Dressel</a>, <a href="/search/quant-ph?searchtype=author&query=Jordan%2C+A+N">Andrew N. Jordan</a>, <a href="/search/quant-ph?searchtype=author&query=Santiago%2C+D+I">David I. Santiago</a>, <a href="/search/quant-ph?searchtype=author&query=Siddiqi%2C+I">Irfan Siddiqi</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="2411.04442v1-abstract-short" style="display: inline;"> The ubiquitous noise in quantum system hinders the advancement of quantum information processing and has driven the emergence of different hardware-efficient quantum error correction protocols. Among them, qubits with structured noise, especially with biased noise, are one of the most promising platform to achieve fault-tolerance due to the high error thresholds of quantum error correction codes t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.04442v1-abstract-full').style.display = 'inline'; document.getElementById('2411.04442v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.04442v1-abstract-full" style="display: none;"> The ubiquitous noise in quantum system hinders the advancement of quantum information processing and has driven the emergence of different hardware-efficient quantum error correction protocols. Among them, qubits with structured noise, especially with biased noise, are one of the most promising platform to achieve fault-tolerance due to the high error thresholds of quantum error correction codes tailored for them. Nevertheless, their quantum operations are challenging and the demonstration of their performance beyond the fault-tolerant threshold remain incomplete. Here, we leverage Schr枚dinger cat states in a scalable planar superconducting nonlinear oscillator to thoroughly characterize the high-fidelity single-qubit quantum operations with systematic quantum tomography and benchmarking tools, demonstrating the state-of-the-art performance of operations crossing the fault-tolerant threshold of the XZZX surface code. These results thus embody a transformative milestone in the exploration of quantum systems with structured error channels. Notably, our framework is extensible to other types of structured-noise systems, paving the way for systematic characterization and validation of novel quantum platforms with structured noise. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.04442v1-abstract-full').style.display = 'none'; document.getElementById('2411.04442v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 12 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/2410.23674">arXiv:2410.23674</a> <span> [<a href="https://arxiv.org/pdf/2410.23674">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Atom-light-correlated quantum interferometer with memory-induced phase comb </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+W">Wenfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+X">Xinyun Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+J">Jie Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Z">Zeliang Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+K">Keye Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chun-Hua Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yuan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+B">Bixuan Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weiping Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liqing Chen</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="2410.23674v1-abstract-short" style="display: inline;"> Precise phase measurements by interferometers are crucial in science for detecting subtle changes, such as gravitational waves. However, phase sensitivity is typically limited by the standard quantum limit (SQL) with uncorrelated particles N. This limit can be surpassed using quantum correlations, but achieving high-quality correlations in large systems is challenging. Here, we propose and demonst… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23674v1-abstract-full').style.display = 'inline'; document.getElementById('2410.23674v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.23674v1-abstract-full" style="display: none;"> Precise phase measurements by interferometers are crucial in science for detecting subtle changes, such as gravitational waves. However, phase sensitivity is typically limited by the standard quantum limit (SQL) with uncorrelated particles N. This limit can be surpassed using quantum correlations, but achieving high-quality correlations in large systems is challenging. Here, we propose and demonstrate an atom-light hybrid quantum interferometry whose sensitivity is enhanced beyond the SQL with atom-light quantum correlation and newly developed phase comb superposition via atomic-memory-assisted multiple quantum amplification. Finally, a phase sensitivity beyond the SQL of up to $8.3\pm 0.2$ dB is achieved, especially at $N=4 \times10^{13}/s$, resulting in both atomic and optical phase sensitivities of $6\times10^{-8} rad/\sqrt{Hz}$. This technique can advance sensitive quantum measurements in various fields. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23674v1-abstract-full').style.display = 'none'; document.getElementById('2410.23674v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 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/2410.19275">arXiv:2410.19275</a> <span> [<a href="https://arxiv.org/pdf/2410.19275">pdf</a>, <a href="https://arxiv.org/ps/2410.19275">ps</a>, <a href="https://arxiv.org/format/2410.19275">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</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"> Finite Temperature Casimir Effect of Scalar Field: Revisit and New Results </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Sheng-Yan Li</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="2410.19275v2-abstract-short" style="display: inline;"> For both the one-dimensional and three-dimensional scalar fields at finite temperature, we find the analytic expressions of Gibbs free energy, Casimir force, and Casimir entropy. These results show that the widely used low-temperature approximation of thermal correction of Casimir force, $蟺{T}e^{-蟺{v}\hbar/aT}/2a^3$, have large errors with the exact solution. Here $T$, $v$ and $a$ represent the fi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.19275v2-abstract-full').style.display = 'inline'; document.getElementById('2410.19275v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.19275v2-abstract-full" style="display: none;"> For both the one-dimensional and three-dimensional scalar fields at finite temperature, we find the analytic expressions of Gibbs free energy, Casimir force, and Casimir entropy. These results show that the widely used low-temperature approximation of thermal correction of Casimir force, $蟺{T}e^{-蟺{v}\hbar/aT}/2a^3$, have large errors with the exact solution. Here $T$, $v$ and $a$ represent the finite temperature, the velocity of scalar field, and the distance between the two boundaries of the fields, respectively. $\hbar$ is the reduced Planck's constant. For three-dimensional scalar field, we find the leading order thermal correction of Gibbs free energy density, $F(a,T)=3味(7/2)aT^4/8蟺^{3/2}(v\hbar)^3$, where $味(.)$ represents the Riemann $味$ function. This thermal correction can not be cancelled by the blackbody radiation density, $蟺^2{a}T^4/90(v\hbar)^3$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.19275v2-abstract-full').style.display = 'none'; document.getElementById('2410.19275v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 9 figures (Figures 5,8,9 are revised)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16635">arXiv:2410.16635</a> <span> [<a href="https://arxiv.org/pdf/2410.16635">pdf</a>, <a href="https://arxiv.org/format/2410.16635">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="Quantum Gases">cond-mat.quant-gas</span> </div> </div> <p class="title is-5 mathjax"> Bounding the Sample Fluctuation for Pure States Certification with Local Random Measurement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Langxuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+P">Pengfei Zhang</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="2410.16635v1-abstract-short" style="display: inline;"> Remarkable breakthroughs in quantum science and technology are demanding for more efficient methods in analyzing quantum many-body states. A significant challenge in this field is to verify whether a quantum state prepared by quantum devices in the lab accurately matches the desired target pure state. Recent advancements in randomized measurement techniques have provided fresh insights in this are… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16635v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16635v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16635v1-abstract-full" style="display: none;"> Remarkable breakthroughs in quantum science and technology are demanding for more efficient methods in analyzing quantum many-body states. A significant challenge in this field is to verify whether a quantum state prepared by quantum devices in the lab accurately matches the desired target pure state. Recent advancements in randomized measurement techniques have provided fresh insights in this area. Specifically, protocols such as classical shadow tomography and shadow overlap have been proposed. Building on these developments, we investigate the fundamental properties of schemes that certify pure quantum states through random local Haar measurements. We derive bounds for sample fluctuations that are applicable regardless of the specific estimator construction. These bounds depend on the operator size distribution of either the observable used to estimate fidelity or the valid variation of the reduced density matrix for arbitrary observables. Our results unveil the intrinsic interplay between operator complexity and the efficiency of quantum algorithms, serving as an obstacle to local certification of pure states with long-range entanglement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16635v1-abstract-full').style.display = 'none'; document.getElementById('2410.16635v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 1 figure + supplementry 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/2410.16091">arXiv:2410.16091</a> <span> [<a href="https://arxiv.org/pdf/2410.16091">pdf</a>, <a href="https://arxiv.org/format/2410.16091">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="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-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/PhysRevResearch.7.L012013">10.1103/PhysRevResearch.7.L012013 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Neural Quantum Propagators for Driven-Dissipative Quantum Dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jiaji Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Benavides-Riveros%2C+C+L">Carlos L. Benavides-Riveros</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lipeng Chen</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="2410.16091v1-abstract-short" style="display: inline;"> Describing the dynamics of strong-laser driven open quantum systems is a very challenging task that requires the solution of highly involved equations of motion. While machine learning techniques are being applied with some success to simulate the time evolution of individual quantum states, their use to approximate time-dependent operators (that can evolve various states) remains largely unexplor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16091v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16091v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16091v1-abstract-full" style="display: none;"> Describing the dynamics of strong-laser driven open quantum systems is a very challenging task that requires the solution of highly involved equations of motion. While machine learning techniques are being applied with some success to simulate the time evolution of individual quantum states, their use to approximate time-dependent operators (that can evolve various states) remains largely unexplored. In this work, we develop driven neural quantum propagators (NQP), a universal neural network framework that solves driven-dissipative quantum dynamics by approximating propagators rather than wavefunctions or density matrices. NQP can handle arbitrary initial quantum states, adapt to various external fields, and simulate long-time dynamics, even when trained on far shorter time windows. Furthermore, by appropriately configuring the external fields, our trained NQP can be transferred to systems governed by different Hamiltonians. We demonstrate the effectiveness of our approach by studying the spin-boson and the three-state transition Gamma models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16091v1-abstract-full').style.display = 'none'; document.getElementById('2410.16091v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, comment are welcome!</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 7, L012013 (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.15375">arXiv:2410.15375</a> <span> [<a href="https://arxiv.org/pdf/2410.15375">pdf</a>, <a href="https://arxiv.org/ps/2410.15375">ps</a>, <a href="https://arxiv.org/format/2410.15375">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"> Preparing Spin Squeezed States via Adaptive Genetic Algorithm </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Yiming Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Libo Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+H">Hongyang Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+X">Xiaolong Zhao</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="2410.15375v1-abstract-short" style="display: inline;"> We introduce a novel strategy employing an adaptive genetic algorithm (GA) for iterative optimization of control sequences to generate quantum nonclassical states. Its efficacy is demonstrated by preparing spin-squeezed states in an open collective spin model governed by a linear control field. Inspired by Darwinian evolution, the algorithm iteratively refines control sequences using crossover, mu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15375v1-abstract-full').style.display = 'inline'; document.getElementById('2410.15375v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.15375v1-abstract-full" style="display: none;"> We introduce a novel strategy employing an adaptive genetic algorithm (GA) for iterative optimization of control sequences to generate quantum nonclassical states. Its efficacy is demonstrated by preparing spin-squeezed states in an open collective spin model governed by a linear control field. Inspired by Darwinian evolution, the algorithm iteratively refines control sequences using crossover, mutation, and elimination strategies, starting from a coherent spin state within a dissipative and dephasing environment. An adaptive parameter adjustment mechanism further enhances optimization. Our approach, compared to constant control schemes, yields a variety of control sequences capable of maintaining squeezing for the collective spin model. Furthermore, the proposed strategy exhibits increased effectiveness in diverse systems, while reservoir thermal excitations are shown to negatively impact control outcomes. We discuss feasible experimental implementations and potential extensions to alternative quantum systems, and the adaptability of the GA module. This research establishes the foundation for utilizing GA-like strategies in controlling quantum systems and achieving desired nonclassical states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15375v1-abstract-full').style.display = 'none'; document.getElementById('2410.15375v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.15253">arXiv:2410.15253</a> <span> [<a href="https://arxiv.org/pdf/2410.15253">pdf</a>, <a href="https://arxiv.org/format/2410.15253">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Multipartite entangling power by von Neumann entropy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+X">Xinyu Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Z">Zhiwei Song</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</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="2410.15253v1-abstract-short" style="display: inline;"> Quantifying the entanglement generation of a multipartite unitary operation is a key problem in quantum information processing. We introduce the definition of multipartite entangling, assisted entangling, and disentangling power, which is a natural generalization of the bipartite ones. We show that they are assumed at a specified quantum state. We analytically derive the entangling power of Schmid… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15253v1-abstract-full').style.display = 'inline'; document.getElementById('2410.15253v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.15253v1-abstract-full" style="display: none;"> Quantifying the entanglement generation of a multipartite unitary operation is a key problem in quantum information processing. We introduce the definition of multipartite entangling, assisted entangling, and disentangling power, which is a natural generalization of the bipartite ones. We show that they are assumed at a specified quantum state. We analytically derive the entangling power of Schmidt-rank-two multi-qubit unitary operations by the minimal convex sum of modulo-one complex numbers. Besides we show the necessary and sufficient condition that the assisted entangling power of Schmidt-rank-two unitary operations reaches the maximum. We further investigate the widely-used multi-qubit gates, for example, the entangling and assisted entangling power of the $n$-qubit Toffoli gate is one ebit. The entangling power of the three-qubit Fredkin gate is two ebits, and that of the four-qubit Fredkin gate is in two to $\log_25$ ebits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15253v1-abstract-full').style.display = 'none'; document.getElementById('2410.15253v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.10947">arXiv:2410.10947</a> <span> [<a href="https://arxiv.org/pdf/2410.10947">pdf</a>, <a href="https://arxiv.org/format/2410.10947">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="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Bandwidth-tunable Telecom Single Photons Enabled by Low-noise Optomechanical Transduction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Korsch%2C+A+R">Alexander Rolf Korsch</a>, <a href="/search/quant-ph?searchtype=author&query=Kersul%2C+C+M">Cau锚 Moreno Kersul</a>, <a href="/search/quant-ph?searchtype=author&query=Benevides%2C+R">Rodrigo Benevides</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Y">Yong Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Alegre%2C+T+P+M">Thiago P. Mayer Alegre</a>, <a href="/search/quant-ph?searchtype=author&query=Gr%C3%B6blacher%2C+S">Simon Gr枚blacher</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="2410.10947v1-abstract-short" style="display: inline;"> Single-photon sources are of fundamental importance to emergent quantum technologies. Nano-structured optomechanical crystals provide an attractive platform for single photon generation due to their unique engineering freedom and compatibility with on-chip silicon fabrication. However, optical absorption heating has thus far prevented these systems from being widely used in practical applications.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10947v1-abstract-full').style.display = 'inline'; document.getElementById('2410.10947v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.10947v1-abstract-full" style="display: none;"> Single-photon sources are of fundamental importance to emergent quantum technologies. Nano-structured optomechanical crystals provide an attractive platform for single photon generation due to their unique engineering freedom and compatibility with on-chip silicon fabrication. However, optical absorption heating has thus far prevented these systems from being widely used in practical applications. Here, we overcome this limitation through the use of a quasi-two-dimensional optomechanical crystal structure and demonstrate an on-chip source of single photons natively at telecom wavelength. We verify the low thermal noise and resulting high purity of the generated single photons through a Hanbury Brown-Twiss experiment with $g^{(2)}(0)=0.35^{+0.10}_{-0.08}$. Furthermore, we perform Hong-Ou-Mandel interference of the emitted photons showcasing the indistinguishability and coherence of photons generated from our source with visibility $V=0.52 \pm 0.15$ after 1.43 km of fiber delay line. With the possibility of using the mechanical mode as a quantum memory, we can retrieve the single photons on-demand. Crucial for applications, the optomechanical interaction at the heart of our device allows the bandwidth of emitted single photons to be tuned over a large range from 100 kHz to several hundreds of MHz, which makes them directly compatible with leading quantum memory platforms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10947v1-abstract-full').style.display = 'none'; document.getElementById('2410.10947v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.10275">arXiv:2410.10275</a> <span> [<a href="https://arxiv.org/pdf/2410.10275">pdf</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> <p class="title is-5 mathjax"> Probing the Meissner effect in pressurized bilayer nickelate superconductors using diamond quantum sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wen%2C+J">Junyan Wen</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yue Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Gang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Z">Ze-Xu He</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+N">Ningning Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+T">Tenglong Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaoli Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+F">Feng Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liucheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+M">Miao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+J">Jing-Wei Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xiaobing Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xin-Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+G">Gang-Qin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+J">Jinguang Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+X">Xiaohui Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.10275v1-abstract-short" style="display: inline;"> Recent reports on the signatures of high-temperature superconductivity with a critical temperature Tc close to 80 K have triggered great research interest and extensive follow-up studies. Although zero-resistance state has been successfully achieved under improved hydrostatic pressure conditions, there is no clear evidence of superconducting diamagnetism in pressurized… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10275v1-abstract-full').style.display = 'inline'; document.getElementById('2410.10275v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.10275v1-abstract-full" style="display: none;"> Recent reports on the signatures of high-temperature superconductivity with a critical temperature Tc close to 80 K have triggered great research interest and extensive follow-up studies. Although zero-resistance state has been successfully achieved under improved hydrostatic pressure conditions, there is no clear evidence of superconducting diamagnetism in pressurized $\mathrm{La_{3}Ni_{2}O_{7-未}}$ due to the low superconducting volume fraction and limited magnetic measurement techniques under high pressure conditions. Here, using shallow nitrogen-vacancy centers implanted on the culet of diamond anvils as in-situ quantum sensors, we observe convincing evidence for the Meissner effect in polycrystalline samples $\mathrm{La_{3}Ni_{2}O_{7-未}}$ and $\mathrm{La_{2}PrNi_{2}O_{7}}$: the magnetic field expulsion during both field cooling and field warming processes. The correlated measurements of Raman spectra and NV-based magnetic imaging indicate an incomplete structural transformation related to the displacement of oxygen ions emerging in the non-superconducting region. Furthermore, comparative experiments on different pressure transmitting media (silicone oil and KBr) and nickelates ($\mathrm{La_{3}Ni_{2}O_{7-未}}$ and $\mathrm{La_{2}PrNi_{2}O_{7}}$) reveal that an improved hydrostatic pressure conditions and the substitution of La by Pr in $\mathrm{La_{3}Ni_{2}O_{7-未}}$ can dramatically increase the superconductivity. Our work clarifies the controversy about the Meissner effect of bilayer nickelate and contributes to a deeper understanding of the mechanism of nickelate high-temperature superconductors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.10275v1-abstract-full').style.display = 'none'; document.getElementById('2410.10275v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.09327">arXiv:2410.09327</a> <span> [<a href="https://arxiv.org/pdf/2410.09327">pdf</a>, <a href="https://arxiv.org/format/2410.09327">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="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Diagnosing Strong-to-Weak Symmetry Breaking via Wightman Correlators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zeyu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Langxuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yuke Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+S">Shuyan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+P">Pengfei Zhang</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="2410.09327v1-abstract-short" style="display: inline;"> Symmetry plays a fundamental role in quantum many-body physics, and a central concept is spontaneous symmetry breaking, which imposes crucial constraints on the possible quantum phases and their transitions. Recent developments have extended the discussion of symmetry and its breaking to mixed states, enhancing our understanding of novel quantum phases that have no counterpart in pure states. Spec… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.09327v1-abstract-full').style.display = 'inline'; document.getElementById('2410.09327v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.09327v1-abstract-full" style="display: none;"> Symmetry plays a fundamental role in quantum many-body physics, and a central concept is spontaneous symmetry breaking, which imposes crucial constraints on the possible quantum phases and their transitions. Recent developments have extended the discussion of symmetry and its breaking to mixed states, enhancing our understanding of novel quantum phases that have no counterpart in pure states. Specific attention has been paid to scenarios where a strongly symmetric density matrix exhibits spontaneous symmetry breaking to weak symmetry, characterized by the fidelity correlator. In this work, we propose the Wightman correlator as an alternative diagnostic tool. This construction relies on the introduction of the thermofield double state for a generic density matrix, which maps the strong symmetry of the density matrix to the doubled symmetry of the pure state, allowing the Wightman correlator to emerge naturally as a standard probe of symmetry breaking. We prove the equivalence between the Wightman function and the fidelity correlator in defining strong-to-weak symmetry breaking, and examine explicit examples involving spin glasses, thermal density matrices, and the decohered Ising model. Additionally, we discuss a susceptibility interpretation of the Wightman correlator. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.09327v1-abstract-full').style.display = 'none'; document.getElementById('2410.09327v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 1 figure + 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/2409.20459">arXiv:2409.20459</a> <span> [<a href="https://arxiv.org/pdf/2409.20459">pdf</a>, <a href="https://arxiv.org/ps/2409.20459">ps</a>, <a href="https://arxiv.org/format/2409.20459">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</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"> Measuring Coherent Radio and Microwave Photons from the Solar Corona </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+Z">Zizang Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Kephart%2C+T+W">Thomas W. Kephart</a>, <a href="/search/quant-ph?searchtype=author&query=Berera%2C+A">Arjun Berera</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="2409.20459v3-abstract-short" style="display: inline;"> The rates of production of radio/microwave N-identical photons states |N> from stimulated emission in the solar atmosphere are estimated. Effects of various decohering factors are shown to be small. Ground based measurements of these quantum states via the inverse HOM effect are proposed. We argue that a signal is detectable and far above the noise in several cases. </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.20459v3-abstract-full" style="display: none;"> The rates of production of radio/microwave N-identical photons states |N> from stimulated emission in the solar atmosphere are estimated. Effects of various decohering factors are shown to be small. Ground based measurements of these quantum states via the inverse HOM effect are proposed. We argue that a signal is detectable and far above the noise in several cases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.20459v3-abstract-full').style.display = 'none'; document.getElementById('2409.20459v3-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.19046">arXiv:2409.19046</a> <span> [<a href="https://arxiv.org/pdf/2409.19046">pdf</a>, <a href="https://arxiv.org/format/2409.19046">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</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"> Subsystem entropy in 2d CFT and KdV ETH </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liangyu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Dymarsky%2C+A">Anatoly Dymarsky</a>, <a href="/search/quant-ph?searchtype=author&query=Tian%2C+J">Jia Tian</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Huajia 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="2409.19046v1-abstract-short" style="display: inline;"> We study subsystem entropy in 2d CFTs, for subsystems constituting a finite fraction of the full system. We focus on the extensive contribution, which scales linearly with the subsystem size in the thermodynamic limit. We employ the so-called diagonal approximation to evaluate subsystem entropy for the chaotic CFTs in thermal state (canonical ensemble), microcanonical ensemble, and in a primary st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.19046v1-abstract-full').style.display = 'inline'; document.getElementById('2409.19046v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.19046v1-abstract-full" style="display: none;"> We study subsystem entropy in 2d CFTs, for subsystems constituting a finite fraction of the full system. We focus on the extensive contribution, which scales linearly with the subsystem size in the thermodynamic limit. We employ the so-called diagonal approximation to evaluate subsystem entropy for the chaotic CFTs in thermal state (canonical ensemble), microcanonical ensemble, and in a primary state, matching previously known results. We then proceed to find analytic expressions for the subsystem entropy at leading order in $c$, when the global CFT state is the KdV generalized Gibbs ensemble or the KdV microcanonical ensemble. Previous studies of primary eigenstates have shown that, akin to fixed-area states in AdS/CFT, corresponding subsystem entanglement spectrum is flat. This behavior is seemingly in sharp contradiction with the one for the thermal (microcanonical) state, and thus in apparent contradiction with the subsystem Eigenstate Thermalization Hypothesis (ETH). In this work, we resolve this issue by comparing the primary state with the KdV (micro)canonical ensemble. We show that the results are consistent with the KdV-generalized version of the subsystem ETH, in which local properties of quantum eigenstates are governed by their values of conserved KdV charges. Our work solidifies evidence for the KdV-generalized ETH in 2d CFTs and emphasizes Renyi entropy as a sensitive probe of the reduced-density matrix. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.19046v1-abstract-full').style.display = 'none'; document.getElementById('2409.19046v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">54 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.16748">arXiv:2409.16748</a> <span> [<a href="https://arxiv.org/pdf/2409.16748">pdf</a>, <a href="https://arxiv.org/format/2409.16748">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"> Fast unconditional reset and leakage reduction in fixed-frequency transmon qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liangyu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Fors%2C+S+P">Simon Pettersson Fors</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+Z">Zixian Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Ali%2C+A">Anaida Ali</a>, <a href="/search/quant-ph?searchtype=author&query=Abad%2C+T">Tahereh Abad</a>, <a href="/search/quant-ph?searchtype=author&query=Osman%2C+A">Amr Osman</a>, <a href="/search/quant-ph?searchtype=author&query=Moschandreou%2C+E">Eleftherios Moschandreou</a>, <a href="/search/quant-ph?searchtype=author&query=Lienhard%2C+B">Benjamin Lienhard</a>, <a href="/search/quant-ph?searchtype=author&query=Kosen%2C+S">Sandoko Kosen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hang-Xi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Shiri%2C+D">Daryoush Shiri</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tong Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Hill%2C+S">Stefan Hill</a>, <a href="/search/quant-ph?searchtype=author&query=Amin%2C+A">Abdullah-Al Amin</a>, <a href="/search/quant-ph?searchtype=author&query=Rehammar%2C+R">Robert Rehammar</a>, <a href="/search/quant-ph?searchtype=author&query=Dahiya%2C+M">Mamta Dahiya</a>, <a href="/search/quant-ph?searchtype=author&query=Nylander%2C+A">Andreas Nylander</a>, <a href="/search/quant-ph?searchtype=author&query=Rommel%2C+M">Marcus Rommel</a>, <a href="/search/quant-ph?searchtype=author&query=Roudsari%2C+A+F">Anita Fadavi Roudsari</a>, <a href="/search/quant-ph?searchtype=author&query=Caputo%2C+M">Marco Caputo</a>, <a href="/search/quant-ph?searchtype=author&query=Leif%2C+G">Gr枚nberg Leif</a>, <a href="/search/quant-ph?searchtype=author&query=Govenius%2C+J">Joonas Govenius</a>, <a href="/search/quant-ph?searchtype=author&query=Dobsicek%2C+M">Miroslav Dobsicek</a>, <a href="/search/quant-ph?searchtype=author&query=Giannelli%2C+M+F">Michele Faucci Giannelli</a>, <a href="/search/quant-ph?searchtype=author&query=Kockum%2C+A+F">Anton Frisk Kockum</a> , et al. (2 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.16748v2-abstract-short" style="display: inline;"> The realization of fault-tolerant quantum computing requires the execution of quantum error-correction (QEC) schemes, to mitigate the fragile nature of qubits. In this context, to ensure the success of QEC, a protocol capable of implementing both qubit reset and leakage reduction is highly desirable. We demonstrate such a protocol in an architecture consisting of fixed-frequency transmon qubits pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.16748v2-abstract-full').style.display = 'inline'; document.getElementById('2409.16748v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.16748v2-abstract-full" style="display: none;"> The realization of fault-tolerant quantum computing requires the execution of quantum error-correction (QEC) schemes, to mitigate the fragile nature of qubits. In this context, to ensure the success of QEC, a protocol capable of implementing both qubit reset and leakage reduction is highly desirable. We demonstrate such a protocol in an architecture consisting of fixed-frequency transmon qubits pair-wise coupled via tunable couplers -- an architecture that is compatible with the surface code. We use tunable couplers to transfer any undesired qubit excitation to the readout resonator of the qubit, from which this excitation decays into the feedline. In total, the combination of qubit reset, leakage reduction, and coupler reset takes only 83ns to complete. Our reset scheme is fast, unconditional, and achieves fidelities well above 99%, thus enabling fixed-frequency qubit architectures as future implementations of fault-tolerant quantum computers. Our protocol also provides a means to both reduce QEC cycle runtime and improve algorithmic fidelity on quantum computers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.16748v2-abstract-full').style.display = 'none'; document.getElementById('2409.16748v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.14347">arXiv:2409.14347</a> <span> [<a href="https://arxiv.org/pdf/2409.14347">pdf</a>, <a href="https://arxiv.org/format/2409.14347">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"> On the extreme points of sets of absolulely separable and PPT states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Song%2C+Z">Zhiwei Song</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</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="2409.14347v1-abstract-short" style="display: inline;"> The absolutely separable (resp. PPT) states remain separable (resp. positive partial transpose) under any global unitary operation. We present a compact form of the extreme points in the sets of absolutely separable states and PPT states in two-qubit and qubit-qudit systems. The results imply that each extreme point has at most three distinct eigenvalues. We establish a necessary and sufficient co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14347v1-abstract-full').style.display = 'inline'; document.getElementById('2409.14347v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.14347v1-abstract-full" style="display: none;"> The absolutely separable (resp. PPT) states remain separable (resp. positive partial transpose) under any global unitary operation. We present a compact form of the extreme points in the sets of absolutely separable states and PPT states in two-qubit and qubit-qudit systems. The results imply that each extreme point has at most three distinct eigenvalues. We establish a necessary and sufficient condition for determining extreme points of the set of absolutely PPT states in two-qutrit and qutrit-qudit systems, expressed as solvable linear equations. We also demonstrate that any extreme point in qutrit-qudit system has at most seven distinct eigenvalues. We introduce the concept of robustness of nonabsolute separability. It quantifies the minimal amount by which a state needs to mix with other states such that the overall state is absolutely separable. We show that the robustness satisfies positivity, invariance under unitary transformation, monotonicity and convexity, so it is a good measure within the resource theory of nonabsolute separability. Analytical expressions for this measure are given for pure states in arbitrary system and rank-two mixed states in two-qubit system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14347v1-abstract-full').style.display = 'none'; document.getElementById('2409.14347v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 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/2409.13025">arXiv:2409.13025</a> <span> [<a href="https://arxiv.org/pdf/2409.13025">pdf</a>, <a href="https://arxiv.org/format/2409.13025">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"> Hardware-efficient quantum error correction using concatenated bosonic qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Putterman%2C+H">Harald Putterman</a>, <a href="/search/quant-ph?searchtype=author&query=Noh%2C+K">Kyungjoo Noh</a>, <a href="/search/quant-ph?searchtype=author&query=Hann%2C+C+T">Connor T. Hann</a>, <a href="/search/quant-ph?searchtype=author&query=MacCabe%2C+G+S">Gregory S. MacCabe</a>, <a href="/search/quant-ph?searchtype=author&query=Aghaeimeibodi%2C+S">Shahriar Aghaeimeibodi</a>, <a href="/search/quant-ph?searchtype=author&query=Patel%2C+R+N">Rishi N. Patel</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+M">Menyoung Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Jones%2C+W+M">William M. Jones</a>, <a href="/search/quant-ph?searchtype=author&query=Moradinejad%2C+H">Hesam Moradinejad</a>, <a href="/search/quant-ph?searchtype=author&query=Rodriguez%2C+R">Roberto Rodriguez</a>, <a href="/search/quant-ph?searchtype=author&query=Mahuli%2C+N">Neha Mahuli</a>, <a href="/search/quant-ph?searchtype=author&query=Rose%2C+J">Jefferson Rose</a>, <a href="/search/quant-ph?searchtype=author&query=Owens%2C+J+C">John Clai Owens</a>, <a href="/search/quant-ph?searchtype=author&query=Levine%2C+H">Harry Levine</a>, <a href="/search/quant-ph?searchtype=author&query=Rosenfeld%2C+E">Emma Rosenfeld</a>, <a href="/search/quant-ph?searchtype=author&query=Reinhold%2C+P">Philip Reinhold</a>, <a href="/search/quant-ph?searchtype=author&query=Moncelsi%2C+L">Lorenzo Moncelsi</a>, <a href="/search/quant-ph?searchtype=author&query=Alcid%2C+J+A">Joshua Ari Alcid</a>, <a href="/search/quant-ph?searchtype=author&query=Alidoust%2C+N">Nasser Alidoust</a>, <a href="/search/quant-ph?searchtype=author&query=Arrangoiz-Arriola%2C+P">Patricio Arrangoiz-Arriola</a>, <a href="/search/quant-ph?searchtype=author&query=Barnett%2C+J">James Barnett</a>, <a href="/search/quant-ph?searchtype=author&query=Bienias%2C+P">Przemyslaw Bienias</a>, <a href="/search/quant-ph?searchtype=author&query=Carson%2C+H+A">Hugh A. Carson</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+C">Cliff Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Li Chen</a> , et al. (96 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.13025v1-abstract-short" style="display: inline;"> In order to solve problems of practical importance, quantum computers will likely need to incorporate quantum error correction, where a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead typically associated with error correction motivates the search for more hardware-efficient approaches. Here, using a microfabricated superconducting quantum circ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13025v1-abstract-full').style.display = 'inline'; document.getElementById('2409.13025v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.13025v1-abstract-full" style="display: none;"> In order to solve problems of practical importance, quantum computers will likely need to incorporate quantum error correction, where a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead typically associated with error correction motivates the search for more hardware-efficient approaches. Here, using a microfabricated superconducting quantum circuit, we realize a logical qubit memory formed from the concatenation of encoded bosonic cat qubits with an outer repetition code of distance $d=5$. The bosonic cat qubits are passively protected against bit flips using a stabilizing circuit. Cat-qubit phase-flip errors are corrected by the repetition code which uses ancilla transmons for syndrome measurement. We realize a noise-biased CX gate which ensures bit-flip error suppression is maintained during error correction. We study the performance and scaling of the logical qubit memory, finding that the phase-flip correcting repetition code operates below threshold, with logical phase-flip error decreasing with code distance from $d=3$ to $d=5$. Concurrently, the logical bit-flip error is suppressed with increasing cat-qubit mean photon number. The minimum measured logical error per cycle is on average $1.75(2)\%$ for the distance-3 code sections, and $1.65(3)\%$ for the longer distance-5 code, demonstrating the effectiveness of bit-flip error suppression throughout the error correction cycle. These results, where the intrinsic error suppression of the bosonic encodings allows us to use a hardware-efficient outer error correcting code, indicate that concatenated bosonic codes are a compelling paradigm for reaching fault-tolerant quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13025v1-abstract-full').style.display = 'none'; document.getElementById('2409.13025v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Comments on the manuscript welcome!</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.05439">arXiv:2409.05439</a> <span> [<a href="https://arxiv.org/pdf/2409.05439">pdf</a>, <a href="https://arxiv.org/ps/2409.05439">ps</a>, <a href="https://arxiv.org/format/2409.05439">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="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> Phases of quartic scalar theories and PT symmetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Leqian Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Sarkar%2C+S">Sarben Sarkar</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="2409.05439v2-abstract-short" style="display: inline;"> For quantum mechanical anharmonic oscillator-type Hamiltonians, it is shown that there is a relation between the energy eigenvalues of parity symmetric and PT-symmetric phases for weak coupling. The possibility of such a relation was conjectured by Ai, Bender and Sarkar on examining the imaginary part of the ground state energy using path integrals. In the weak coupling limit, we show that the con… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05439v2-abstract-full').style.display = 'inline'; document.getElementById('2409.05439v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.05439v2-abstract-full" style="display: none;"> For quantum mechanical anharmonic oscillator-type Hamiltonians, it is shown that there is a relation between the energy eigenvalues of parity symmetric and PT-symmetric phases for weak coupling. The possibility of such a relation was conjectured by Ai, Bender and Sarkar on examining the imaginary part of the ground state energy using path integrals. In the weak coupling limit, we show that the conjecture is true also for the real part of the ground state energy and of the excited state energies. However, the conjecture is false for strong coupling. The analogous relation for partition functions in zero spacetime dimensions is valid for many cases. However $O(N)$ symmetric multi-component scalar fields, with $N>1$ and a quartic interaction, do not satisfy the conjecture for zero and one dimensional spacetime. The possibility that the conjecture is valid, for a single component field theory in higher dimensional spacetimes, is discussed in a simplified model. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05439v2-abstract-full').style.display = 'none'; document.getElementById('2409.05439v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> KCL-PH-TH/2024- 42 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.16997">arXiv:2408.16997</a> <span> [<a href="https://arxiv.org/pdf/2408.16997">pdf</a>, <a href="https://arxiv.org/format/2408.16997">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </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.133.090402">10.1103/PhysRevLett.133.090402 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Verification of Demon-Involved Fluctuation Theorems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yan%2C+L+-">L. -L. Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Bu%2C+J+-">J. -T. Bu</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Q">Q. Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+K">K. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K+-">K. -F. Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+F">F. Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+S+-">S. -L. Su</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">L. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">J. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+G">Gang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+M">M. Feng</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="2408.16997v1-abstract-short" style="display: inline;"> The limit of energy saving in the control of small systems has recently attracted much interest due to the concept refinement of the Maxwell demon. Inspired by a newly proposed set of fluctuation theorems, we report the first experimental verification of these equalities and inequalities in a ultracold 40Ca ion system, confirming the intrinsic nonequilibrium in the system due to involvement of the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16997v1-abstract-full').style.display = 'inline'; document.getElementById('2408.16997v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.16997v1-abstract-full" style="display: none;"> The limit of energy saving in the control of small systems has recently attracted much interest due to the concept refinement of the Maxwell demon. Inspired by a newly proposed set of fluctuation theorems, we report the first experimental verification of these equalities and inequalities in a ultracold 40Ca ion system, confirming the intrinsic nonequilibrium in the system due to involvement of the demon. Based on elaborately designed demon-involved control protocols, such as the Szilard engine protocol, we provide experimentally quantitative evidence of the dissipative information, and observe tighter bounds of both the extracted work and the demon's efficacy than the limits predicted by the Sagawa-Ueda theorem. Our results substantiate a close connection between the physical nature of information and nonequilibrium processes at the microscale, which help further understanding the thermodynamic characteristics of information and the optimal design of nanoscale and smaller systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16997v1-abstract-full').style.display = 'none'; document.getElementById('2408.16997v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review Letters 133, 090402 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.16366">arXiv:2408.16366</a> <span> [<a href="https://arxiv.org/pdf/2408.16366">pdf</a>, <a href="https://arxiv.org/format/2408.16366">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> A small footprint travelling-wave parametric amplifier with a high Signal-to-Noise Ratio improvement in a wide band </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Nilsson%2C+H+R">Hampus Renberg Nilsson</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liangyu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Tancredi%2C+G">Giovanna Tancredi</a>, <a href="/search/quant-ph?searchtype=author&query=Rehammar%2C+R">Robert Rehammar</a>, <a href="/search/quant-ph?searchtype=author&query=Shiri%2C+D">Daryoush Shiri</a>, <a href="/search/quant-ph?searchtype=author&query=Nilsson%2C+F">Filip Nilsson</a>, <a href="/search/quant-ph?searchtype=author&query=Osman%2C+A">Amr Osman</a>, <a href="/search/quant-ph?searchtype=author&query=Shumeiko%2C+V">Vitaly Shumeiko</a>, <a href="/search/quant-ph?searchtype=author&query=Delsing%2C+P">Per Delsing</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.16366v1-abstract-short" style="display: inline;"> We characterise a small footprint travelling-wave parametric amplifier (TWPA). The TWPA is built with magnetically flux-tunable superconducting nonlinear asymmetric inductive elements (SNAILs) and parallel-plate capacitors. It implements three-wave mixing (3WM) with resonant phase matching (RPM), a small cutoff frequency for high gain per unitcell and impedance matching networks for large bandwidt… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16366v1-abstract-full').style.display = 'inline'; document.getElementById('2408.16366v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.16366v1-abstract-full" style="display: none;"> We characterise a small footprint travelling-wave parametric amplifier (TWPA). The TWPA is built with magnetically flux-tunable superconducting nonlinear asymmetric inductive elements (SNAILs) and parallel-plate capacitors. It implements three-wave mixing (3WM) with resonant phase matching (RPM), a small cutoff frequency for high gain per unitcell and impedance matching networks for large bandwidth impedance matching. The device has 200 unitcells and a physical footprint of only 1.1 mm^2, yet demonstrates an average parametric gain of 19 dB over a 3 GHz bandwidth, an average effective signal-to-noise ratio improvement of 10 dB and a clear speedup of qubit readout time. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.16366v1-abstract-full').style.display = 'none'; document.getElementById('2408.16366v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages + 2 appendix pages, 3 figures + 2 appendix 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/2408.11652">arXiv:2408.11652</a> <span> [<a href="https://arxiv.org/pdf/2408.11652">pdf</a>, <a href="https://arxiv.org/format/2408.11652">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div 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/10.1088/0256-307X/41/12/127302">10.1088/0256-307X/41/12/127302 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum entanglement and non-Hermiticity in free-fermion systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Li-Mei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yao Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S+A">Shuai A. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+P">Peng Ye</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="2408.11652v3-abstract-short" style="display: inline;"> This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems. We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation, alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features. A pedagogical discussion is provided on the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11652v3-abstract-full').style.display = 'inline'; document.getElementById('2408.11652v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.11652v3-abstract-full" style="display: none;"> This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems. We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation, alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features. A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems. Building on this foundation, we focus on how entanglement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts, with a review of the general properties that emerge. Finally, we highlight various concrete studies, demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics. The entanglement spectrum also reflects the topological characteristics of non-Hermitian topological systems, while unique non-Hermitian entanglement behaviors are also discussed. The review is concluded with several future directions. Through this review, we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11652v3-abstract-full').style.display = 'none'; document.getElementById('2408.11652v3-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">A Topical Review of the Interplay of Entanglement and Non-Hermitian Physics (to appear in the Special Issue of Non-Hermitian Physics in Chin. Phys. Lett.). version 3; ~15p, 1figure, texts and refs. updated, approximate to final version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chinese Physics Letters (2024 online) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.10471">arXiv:2408.10471</a> <span> [<a href="https://arxiv.org/pdf/2408.10471">pdf</a>, <a href="https://arxiv.org/ps/2408.10471">ps</a>, <a href="https://arxiv.org/format/2408.10471">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="Mathematical Physics">math-ph</span> </div> </div> <p class="title is-5 mathjax"> Eigenvalues and eigenvectors of complex Hadamard matrices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liang%2C+M">Mengfan Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</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="2408.10471v1-abstract-short" style="display: inline;"> Characterizing the $6\times 6$ complex Hadamard matrices (CHMs) is an open problem in linear algebra and quantum information. In this paper, we investigate the eigenvalues and eigenvectors of CHMs. We show that any $n\times n$ CHM with dephased form has two constant eigenvalues $\pm\sqrt{n}$ and has two constant eigenvectors. We obtain the maximum numbers of identical eigenvalues of $6\times 6$ CH… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10471v1-abstract-full').style.display = 'inline'; document.getElementById('2408.10471v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.10471v1-abstract-full" style="display: none;"> Characterizing the $6\times 6$ complex Hadamard matrices (CHMs) is an open problem in linear algebra and quantum information. In this paper, we investigate the eigenvalues and eigenvectors of CHMs. We show that any $n\times n$ CHM with dephased form has two constant eigenvalues $\pm\sqrt{n}$ and has two constant eigenvectors. We obtain the maximum numbers of identical eigenvalues of $6\times 6$ CHMs with dephased form and we extend this result to arbitrary dimension. We also show that there is no $6\times 6$ CHM with four identical eigenvalues. We conjecture that the eigenvalues and eigenvectors of $6\times 6$ CHMs will lead to the complete classification of $6\times 6$ CHMs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10471v1-abstract-full').style.display = 'none'; document.getElementById('2408.10471v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages,0 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/2408.08574">arXiv:2408.08574</a> <span> [<a href="https://arxiv.org/pdf/2408.08574">pdf</a>, <a href="https://arxiv.org/format/2408.08574">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"> The detection power of real entanglement witnesses under local unitary equivalence </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shen%2C+Y">Yi Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Bian%2C+Z">Zhihao Bian</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="2408.08574v1-abstract-short" style="display: inline;"> Since the birth of quantum theory, it has been controversial that whether real numbers are adequate to describe its formalism. Recently, the imaginary unit $i$ has been experimentally proven to be indispensable for quantum mechanics. It motivates us to study the differences in detection power between real and complex entanglement witnesses (EWs), and analyze the detection power of real EWs under l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08574v1-abstract-full').style.display = 'inline'; document.getElementById('2408.08574v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.08574v1-abstract-full" style="display: none;"> Since the birth of quantum theory, it has been controversial that whether real numbers are adequate to describe its formalism. Recently, the imaginary unit $i$ has been experimentally proven to be indispensable for quantum mechanics. It motivates us to study the differences in detection power between real and complex entanglement witnesses (EWs), and analyze the detection power of real EWs under local equivalences. We show that a real EW must detect a real entangled state, and conversely a real entangled state must be detected by a real EW. We present a necessary and sufficient condition for the entangled states detected by real EWs, and give a specific example which implies the detection limitations of real EWs. Then, we conjecture that all entangled states are detected by the EWs locally equivalent to real ones. We prove the conjecture for all states with non-positive partial transpose. We also derive a necessary and sufficient condition for the complex PPT (positive-partial-transpose) entangled states detected by the EWs locally equivalent to real ones. We further prove the conjecture for a family of two-quqart PPT entangled states. Another way to figure out the conjecture is to check whether a counterexample exists. We propose an equivalent method to examine the existence of a counterexample from a set-theoretic perspective, and provide some supporting evidence of non-existence. Finally, we derive some results on local projections of EWs with product projectors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08574v1-abstract-full').style.display = 'none'; document.getElementById('2408.08574v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 2 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/2408.08243">arXiv:2408.08243</a> <span> [<a href="https://arxiv.org/pdf/2408.08243">pdf</a>, <a href="https://arxiv.org/format/2408.08243">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="Networking and Internet Architecture">cs.NI</span> </div> </div> <p class="title is-5 mathjax"> From Entanglement Purification Scheduling to Fidelity-constrained Multi-Flow Routing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jia%2C+Z">Ziyue Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</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="2408.08243v2-abstract-short" style="display: inline;"> Recently emerged as a disruptive networking paradigm, quantum networks rely on the mysterious quantum entanglement to teleport qubits without physically transferring quantum particles. However, the state of quantum systems is extremely fragile due to environment noise. A promising technique to combat against quantum decoherence is entanglement purification. To fully exploit its benefit, two fundam… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08243v2-abstract-full').style.display = 'inline'; document.getElementById('2408.08243v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.08243v2-abstract-full" style="display: none;"> Recently emerged as a disruptive networking paradigm, quantum networks rely on the mysterious quantum entanglement to teleport qubits without physically transferring quantum particles. However, the state of quantum systems is extremely fragile due to environment noise. A promising technique to combat against quantum decoherence is entanglement purification. To fully exploit its benefit, two fundamental research questions need to be answered: (1) given an entanglement path, what is the optimal entanglement purification schedule? (2) how to compute min-cost end-to-end entanglement paths subject to fidelity constraint? In this paper, we give algorithmic solutions to both questions. For the first question, we develop an optimal entanglement purification scheduling algorithm for the single-hop case and analyze the \textsc{purify-and-swap} strategy in the multi-hop case by establishing the closed-form condition for its optimality. For the second question, we design a polynomial-time algorithm constructing an $蔚$-optimal fidelity-constrained path. The effectiveness of our algorithms are also numerically demonstrated by extensive simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08243v2-abstract-full').style.display = 'none'; document.getElementById('2408.08243v2-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 12 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/2408.07552">arXiv:2408.07552</a> <span> [<a href="https://arxiv.org/pdf/2408.07552">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum key distribution based on mid-infrared and telecom band two-color entanglement source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wu-Zhen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+C">Chun Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Li Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+R">Ren-Hui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zhao-Qi-Zhi Han</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+M">Ming-Yuan Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiao-Hua Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+D">Di-Yuan Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+M">Meng-Yu Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yin-Hai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zhi-Yuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Bao%2C+W">Wan-Su Bao</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</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="2408.07552v1-abstract-short" style="display: inline;"> Due to the high noise caused by solar background radiation, the existing satellite-based free-space quantum key distribution (QKD) experiments are mainly carried out at night, hindering the establishment of a practical all-day real-time global-scale quantum network. Given that the 3-5 渭m mid-infrared (MIR) band has extremely low solar background radiation and strong scattering resistance, it is on… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.07552v1-abstract-full').style.display = 'inline'; document.getElementById('2408.07552v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.07552v1-abstract-full" style="display: none;"> Due to the high noise caused by solar background radiation, the existing satellite-based free-space quantum key distribution (QKD) experiments are mainly carried out at night, hindering the establishment of a practical all-day real-time global-scale quantum network. Given that the 3-5 渭m mid-infrared (MIR) band has extremely low solar background radiation and strong scattering resistance, it is one of the ideal bands for free-space quantum communication. Here, firstly, we report on the preparation of a high-quality MIR (3370 nm) and telecom band (1555 nm) two-color polarization-entangled photon source, then we use this source to realize a principle QKD based on free-space and fiber hybrid channels in a laboratory. The theoretical analysis clearly shows that a long-distance QKD over 500 km of free-space and 96 km of fiber hybrid channels can be reached simultaneously. This work represents a significant step toward developing all-day global-scale quantum communication networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.07552v1-abstract-full').style.display = 'none'; document.getElementById('2408.07552v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 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/2408.04183">arXiv:2408.04183</a> <span> [<a href="https://arxiv.org/pdf/2408.04183">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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> <p class="title is-5 mathjax"> Quantum-Enhanced Polarimetric Imaging </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xie%2C+M">Meng-Yu Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+S">Su-Jian Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zhao-Qi-Zhi Han</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yin-Hai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+R">Ren-Hui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiao-Hua Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+M">Ming-Yuan Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Li Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yue-Wei Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zhi-Yuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+B">Bao-Sen Shi</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="2408.04183v1-abstract-short" style="display: inline;"> Polarimetric imaging, a technique that captures the invisible polarization-related properties of given materials, has broad applications from fundamental physics to advanced fields such as target recognition, stress detection, biomedical diagnosis and remote sensing. The introduction of quantum sources into classical imaging systems has demonstrated distinct advantages, yet few studies have explor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04183v1-abstract-full').style.display = 'inline'; document.getElementById('2408.04183v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.04183v1-abstract-full" style="display: none;"> Polarimetric imaging, a technique that captures the invisible polarization-related properties of given materials, has broad applications from fundamental physics to advanced fields such as target recognition, stress detection, biomedical diagnosis and remote sensing. The introduction of quantum sources into classical imaging systems has demonstrated distinct advantages, yet few studies have explored their combination with polarimetric imaging. In this study, we present a quantum polarimetric imaging system that integrates polarization-entangled photon pairs into a polarizer-sample-compensator-analyzer (PSRA)-type polarimeter. Our system visualizes the birefringence properties of a periodical-distributed anisotropic material under decreasing illumination levels and diverse disturbing light sources. Compared to the classical system, the quantum approach reveals the superior sensitivity and robustness in low-light conditions, particularly useful in biomedical studies where the low illumination and non-destructive detection are urgently needed. The study also highlights the nonlocality of entangled photons in birefringence measurement, indicating the potential of quantum polarimetric system in the remote sensing domain. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04183v1-abstract-full').style.display = 'none'; document.getElementById('2408.04183v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.01980">arXiv:2408.01980</a> <span> [<a href="https://arxiv.org/pdf/2408.01980">pdf</a>, <a href="https://arxiv.org/format/2408.01980">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"> Measurement Induced Magic Resources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Gongchu Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Si-Qi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+X">Xu-Song Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Huaqing Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yuancheng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">You Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+G">Geng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hamma%2C+A">Alioscia Hamma</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</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="2408.01980v3-abstract-short" style="display: inline;"> Magic states and magic gates are crucial for achieving universal computation, but some important questions about how magic resources should be implemented to attain quantum advantage have remained unexplored, for instance, in the context of Measurement-based Quantum Computation (MQC) with only single-qubit measurements. This work bridges the gap between MQC and the resource theory of magic by intr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.01980v3-abstract-full').style.display = 'inline'; document.getElementById('2408.01980v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.01980v3-abstract-full" style="display: none;"> Magic states and magic gates are crucial for achieving universal computation, but some important questions about how magic resources should be implemented to attain quantum advantage have remained unexplored, for instance, in the context of Measurement-based Quantum Computation (MQC) with only single-qubit measurements. This work bridges the gap between MQC and the resource theory of magic by introducing the concept of ``invested'' and ``potential" magic resources. The former quantifies the magic cost associated with the MQC framework, serving both as a witness of magic resources and an upper bound for the realization of a desired unitary transformation. Potential magic resources represent the maximum achievable magic resource in a given graph structure defining the MQC. We utilize these concepts to analyze the magic resource requirements of the Quantum Fourier Transform (QFT) and provide a fresh perspective on the universality of MQC of different resource states, highlighting the crucial role of non-Pauli measurements for injecting magic. We demonstrate experimentally our theoretical predictions in a high-fidelity four-photon setup and demonstrate the efficiency of MQC in generating magic states, surpassing the limitations of conventional magic state injection methods. Our findings pave the way for future research exploring magic resource optimization and novel distillation schemes within the MQC framework, contributing to the advancement of fault-tolerant universal quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.01980v3-abstract-full').style.display = 'none'; document.getElementById('2408.01980v3-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 11 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/2408.01663">arXiv:2408.01663</a> <span> [<a href="https://arxiv.org/pdf/2408.01663">pdf</a>, <a href="https://arxiv.org/format/2408.01663">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"> On the Hardness of Measuring Magic </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Garcia%2C+R+J">Roy J. Garcia</a>, <a href="/search/quant-ph?searchtype=author&query=Bhole%2C+G">Gaurav Bhole</a>, <a href="/search/quant-ph?searchtype=author&query=Bu%2C+K">Kaifeng Bu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liyuan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Arthanari%2C+H">Haribabu Arthanari</a>, <a href="/search/quant-ph?searchtype=author&query=Jaffe%2C+A">Arthur Jaffe</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="2408.01663v1-abstract-short" style="display: inline;"> Quantum computers promise to solve computational problems significantly faster than classical computers. These 'speed-ups' are achieved by utilizing a resource known as magic. Measuring the amount of magic used by a device allows us to quantify its potential computational power. Without this property, quantum computers are no faster than classical computers. Whether magic can be accurately measure… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.01663v1-abstract-full').style.display = 'inline'; document.getElementById('2408.01663v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.01663v1-abstract-full" style="display: none;"> Quantum computers promise to solve computational problems significantly faster than classical computers. These 'speed-ups' are achieved by utilizing a resource known as magic. Measuring the amount of magic used by a device allows us to quantify its potential computational power. Without this property, quantum computers are no faster than classical computers. Whether magic can be accurately measured on large-scale quantum computers has remained an open problem. To address this question, we introduce Pauli instability as a measure of magic and experimentally measure it on the IBM Eagle quantum processor. We prove that measuring large (i.e., extensive) quantities of magic is intractable. Our results suggest that one may only measure magic when a quantum computer does not provide a speed-up. We support our conclusions with both theoretical and experimental evidence. Our work illustrates the capabilities and limitations of quantum technology in measuring one of the most important resources in quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.01663v1-abstract-full').style.display = 'none'; document.getElementById('2408.01663v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.09860">arXiv:2407.09860</a> <span> [<a href="https://arxiv.org/pdf/2407.09860">pdf</a>, <a href="https://arxiv.org/format/2407.09860">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Quantum Vicsek Model for Active Matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+L+X">L. X. Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L+T">L. T. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C+P">C. P. Sun</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="2407.09860v1-abstract-short" style="display: inline;"> We propose a quantum analog of the Vicsek model, consisting of an ensemble of overdamped spin$-1/2$ particles with ferromagnetic couplings, driven by a uniformly polarized magnetic field. The spontaneous magnetization of the spin components breaks the $SO(3)$ (or $SO(2)$) symmetry, inducing an ordered phase of flocking. We derive the hydrodynamic equations, similar to those formulated by Toner and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09860v1-abstract-full').style.display = 'inline'; document.getElementById('2407.09860v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.09860v1-abstract-full" style="display: none;"> We propose a quantum analog of the Vicsek model, consisting of an ensemble of overdamped spin$-1/2$ particles with ferromagnetic couplings, driven by a uniformly polarized magnetic field. The spontaneous magnetization of the spin components breaks the $SO(3)$ (or $SO(2)$) symmetry, inducing an ordered phase of flocking. We derive the hydrodynamic equations, similar to those formulated by Toner and Tu, by applying a mean-field approximation to the quantum analog model up to the next leading order. Our investigation not only establishes a microscopic connection between the Vicsek model and the Toner-Tu hydrodynamics for active matter, but also aims to inspire further studies of active matter in the quantum regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09860v1-abstract-full').style.display = 'none'; document.getElementById('2407.09860v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.02036">arXiv:2407.02036</a> <span> [<a href="https://arxiv.org/pdf/2407.02036">pdf</a>, <a href="https://arxiv.org/ps/2407.02036">ps</a>, <a href="https://arxiv.org/format/2407.02036">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="High Energy Physics - Phenomenology">hep-ph</span> </div> </div> <p class="title is-5 mathjax"> PT symmetric fermionic particle oscillations in even dimensional representations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Leqian Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Sarkar%2C+S">Sarben Sarkar</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="2407.02036v2-abstract-short" style="display: inline;"> We describe a novel class of quantum mechanical particle oscillations in both relativistic and non-relativistic systems based on $PT$ symmetry and $T^2=-1$ (relevant for fermions), where $P$ is parity and $T$ is time reversal. The Hamiltonians are chosen at the outset to be self-adjoint with respect to a PT inner product. The quantum mechanical time evolution is based on a modified $CPT$ inner pro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02036v2-abstract-full').style.display = 'inline'; document.getElementById('2407.02036v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02036v2-abstract-full" style="display: none;"> We describe a novel class of quantum mechanical particle oscillations in both relativistic and non-relativistic systems based on $PT$ symmetry and $T^2=-1$ (relevant for fermions), where $P$ is parity and $T$ is time reversal. The Hamiltonians are chosen at the outset to be self-adjoint with respect to a PT inner product. The quantum mechanical time evolution is based on a modified $CPT$ inner product constructed in terms of a suitable $C$ operator. The resulting quantum mechanical evolution is shown to be unitary and probability is conserved by the oscillations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02036v2-abstract-full').style.display = 'none'; document.getElementById('2407.02036v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> KCL-PH-TH/2024-36 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.01350">arXiv:2406.01350</a> <span> [<a href="https://arxiv.org/pdf/2406.01350">pdf</a>, <a href="https://arxiv.org/ps/2406.01350">ps</a>, <a href="https://arxiv.org/format/2406.01350">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"> Realization of permutation groups by quantum circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Junchi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+Y">Yangyang Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+H">Hanyi Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin Chen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.01350v1-abstract-short" style="display: inline;"> In this paper, we exclusively utilize CNOT gates for implementing permutation groups generated by more than two elements. In Lemma 1, we recall that three CNOT gates are both necessary and sufficient to execute a two-qubit swap gate operation. Subsequently, in Lemma 2, we show that the maximum number of CNOT gates needed to carry out an n-qubit substitution operation is 3(n-1). Moving forward, our… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01350v1-abstract-full').style.display = 'inline'; document.getElementById('2406.01350v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.01350v1-abstract-full" style="display: none;"> In this paper, we exclusively utilize CNOT gates for implementing permutation groups generated by more than two elements. In Lemma 1, we recall that three CNOT gates are both necessary and sufficient to execute a two-qubit swap gate operation. Subsequently, in Lemma 2, we show that the maximum number of CNOT gates needed to carry out an n-qubit substitution operation is 3(n-1). Moving forward, our analysis in Section 3 reveals that utilizing five or fewer CNOT gates is insufficient for implementing a three-qubit swap gate corresponding to the permutation element (123). Hence six CNOT gates are both necessary and sufficient for implementing (123). This is done by employing a graph-theoretic approach to rigorously validate the results in terms of at most five CNOT gates. Using computational tools, we exhaustively explore all valid circuit diagrams containing exactly six CNOT gates to successfully execute the swap gate for (123), by explaining the equivalence classes in Remark 6 and Table 2. We conclude them in Theorem 7.To extend our analysis to the multiqubit scenario, we present the reducible and irreducible permutation elements in Definition 8. We clarify the equivalence between rows in the multi-qubit space and provide an approximate upper bound for multi-qubits to perform the aforementioned operations in Theorem 9. The comprehensive exploration of this paper aims to pave the way for further advancements in understanding quantum circuit optimization via multiple use of a specific two-qubit gate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01350v1-abstract-full').style.display = 'none'; document.getElementById('2406.01350v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </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=Chen%2C+L&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a 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