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class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.06863">arXiv:2411.06863</a> <span> [<a href="https://arxiv.org/pdf/2411.06863">pdf</a>, <a href="https://arxiv.org/format/2411.06863">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</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="Emerging Technologies">cs.ET</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"> Computable Model-Independent Bounds for Adversarial Quantum Machine Learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bacui Li</a>, <a href="/search/quant-ph?searchtype=author&query=Alpcan%2C+T">Tansu Alpcan</a>, <a href="/search/quant-ph?searchtype=author&query=Thapa%2C+C">Chandra Thapa</a>, <a href="/search/quant-ph?searchtype=author&query=Parampalli%2C+U">Udaya Parampalli</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="2411.06863v1-abstract-short" style="display: inline;"> By leveraging the principles of quantum mechanics, QML opens doors to novel approaches in machine learning and offers potential speedup. However, machine learning models are well-documented to be vulnerable to malicious manipulations, and this susceptibility extends to the models of QML. This situation necessitates a thorough understanding of QML's resilience against adversarial attacks, particula… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06863v1-abstract-full').style.display = 'inline'; document.getElementById('2411.06863v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.06863v1-abstract-full" style="display: none;"> By leveraging the principles of quantum mechanics, QML opens doors to novel approaches in machine learning and offers potential speedup. However, machine learning models are well-documented to be vulnerable to malicious manipulations, and this susceptibility extends to the models of QML. This situation necessitates a thorough understanding of QML's resilience against adversarial attacks, particularly in an era where quantum computing capabilities are expanding. In this regard, this paper examines model-independent bounds on adversarial performance for QML. To the best of our knowledge, we introduce the first computation of an approximate lower bound for adversarial error when evaluating model resilience against sophisticated quantum-based adversarial attacks. Experimental results are compared to the computed bound, demonstrating the potential of QML models to achieve high robustness. In the best case, the experimental error is only 10% above the estimated bound, offering evidence of the inherent robustness of quantum models. This work not only advances our theoretical understanding of quantum model resilience but also provides a precise reference bound for the future development of robust QML algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06863v1-abstract-full').style.display = 'none'; document.getElementById('2411.06863v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 November, 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">21 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/2410.23622">arXiv:2410.23622</a> <span> [<a href="https://arxiv.org/pdf/2410.23622">pdf</a>, <a href="https://arxiv.org/format/2410.23622">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"> Optimality Condition for the Transpose Channel </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bikun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhaoyou Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+G">Guo Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.23622v2-abstract-short" style="display: inline;"> In quantum error correction, the Petz transpose channel serves as a perfect recovery map when the Knill-Laflamme conditions are satisfied. Notably, while perfect recovery is generally infeasible for most quantum channels of finite dimension, the transpose channel remains a versatile tool with near-optimal performance in recovering quantum states. This work introduces and proves, for the first time… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23622v2-abstract-full').style.display = 'inline'; document.getElementById('2410.23622v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.23622v2-abstract-full" style="display: none;"> In quantum error correction, the Petz transpose channel serves as a perfect recovery map when the Knill-Laflamme conditions are satisfied. Notably, while perfect recovery is generally infeasible for most quantum channels of finite dimension, the transpose channel remains a versatile tool with near-optimal performance in recovering quantum states. This work introduces and proves, for the first time, the necessary and sufficient conditions for the strict optimality of the transpose channel in terms of channel fidelity. The violation of this condition can be easily characterized by a simple commutator that can be efficiently computed. We provide multiple examples that substantiate our new findings. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23622v2-abstract-full').style.display = 'none'; document.getElementById('2410.23622v2-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 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/2410.20879">arXiv:2410.20879</a> <span> [<a href="https://arxiv.org/pdf/2410.20879">pdf</a>, <a href="https://arxiv.org/format/2410.20879">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/10.1007/s11433-024-2514-x">10.1007/s11433-024-2514-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Geometric-Like imaginarity: quantification and state conversion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+M">Meng-Li Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Fei%2C+S">Shao-Ming Fei</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="2410.20879v1-abstract-short" style="display: inline;"> From the perspective of resource-theoretic approach, this study explores the quantification of imaginary in quantum physics. We propose a well defined measure of imaginarity, the geometric-like measure of imaginarity. Compared with the usual geometric imaginarity measure, this geometric-like measure of imaginarity exhibits smaller decay difference under quantum noisy channels and higher stability.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20879v1-abstract-full').style.display = 'inline'; document.getElementById('2410.20879v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.20879v1-abstract-full" style="display: none;"> From the perspective of resource-theoretic approach, this study explores the quantification of imaginary in quantum physics. We propose a well defined measure of imaginarity, the geometric-like measure of imaginarity. Compared with the usual geometric imaginarity measure, this geometric-like measure of imaginarity exhibits smaller decay difference under quantum noisy channels and higher stability. As applications, we show that both the optimal probability of state transformations from a pure state to an arbitrary mixed state via real operations, and the maximal probability of stochastic-approximate state transformations from a pure state to an arbitrary mixed state via real operations with a given fidelity $f$, are given by the geometric-like measure of imaginarity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20879v1-abstract-full').style.display = 'none'; document.getElementById('2410.20879v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 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">Report number:</span> February 2025 Vol. 68 No. 2: 220311 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> SCIENCE CHINA Physics, Mechanics & Astronomy 2025 Vol. 68 No. 2: 220311 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16841">arXiv:2410.16841</a> <span> [<a href="https://arxiv.org/pdf/2410.16841">pdf</a>, <a href="https://arxiv.org/format/2410.16841">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 metrology timing limits of biphoton frequency comb </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Baihong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qi-qi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+B">Boxin Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+R">Rui-Bo Jin</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="2410.16841v1-abstract-short" style="display: inline;"> Biphoton frequency comb (BFC), which encompasses multiple discrete frequency modes and represents high-dimensional frequency entanglement, is crucial in quantum information processing due to its high information capacity and error resilience. It also holds significant potential for enhancing timing precision in quantum metrology. Here, we examine quantum metrology timing limits using the BFC as a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16841v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16841v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16841v1-abstract-full" style="display: none;"> Biphoton frequency comb (BFC), which encompasses multiple discrete frequency modes and represents high-dimensional frequency entanglement, is crucial in quantum information processing due to its high information capacity and error resilience. It also holds significant potential for enhancing timing precision in quantum metrology. Here, we examine quantum metrology timing limits using the BFC as a probe state and derive a quantum Cram茅r-Rao bound that scales quadratically with the number of frequency modes. Under ideal conditions (zero loss and perfect visibility), this bound can be saturated by both spectrally non-resolved Hong-Ou-Mandel (HOM) interferometry at zero delay and spectrally resolved HOM interferometry at arbitrary delays. In particular, under imperfect experimental conditions, Fisher information rapidly increases up to its maximum as the mode number increases for a fixed time delay close to zero, indicating that increasing the mode number is an optimal strategy for improving the timing precision in practice. Furthermore, compared with spectrally non-resolved measurement, spectrally resolved measurement is a better strategy due to its higher Fisher information, shorter measurement times, and ambiguity-free dynamic range. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16841v1-abstract-full').style.display = 'none'; document.getElementById('2410.16841v1-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 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">14 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/2410.15389">arXiv:2410.15389</a> <span> [<a href="https://arxiv.org/pdf/2410.15389">pdf</a>, <a href="https://arxiv.org/format/2410.15389">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/sciadv.adr9527">10.1126/sciadv.adr9527 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of quantum superposition of topological defects in a trapped ion quantum simulator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Z">Zhijie Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yukai Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shijiao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Mei%2C+Q">Quanxin Mei</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Gangxi Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Y">Yue Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Qi%2C+B">Binxiang Qi</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zichao Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+P">Panyu Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+L">Luming Duan</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="2410.15389v1-abstract-short" style="display: inline;"> Topological defects are discontinuities of a system protected by global properties, with wide applications in mathematics and physics. While previous experimental studies mostly focused on their classical properties, it has been predicted that topological defects can exhibit quantum superposition. Despite the fundamental interest and potential applications in understanding symmetry-breaking dynami… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15389v1-abstract-full').style.display = 'inline'; document.getElementById('2410.15389v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.15389v1-abstract-full" style="display: none;"> Topological defects are discontinuities of a system protected by global properties, with wide applications in mathematics and physics. While previous experimental studies mostly focused on their classical properties, it has been predicted that topological defects can exhibit quantum superposition. Despite the fundamental interest and potential applications in understanding symmetry-breaking dynamics of quantum phase transitions, its experimental realization still remains a challenge. Here, we report the observation of quantum superposition of topological defects in a trapped-ion quantum simulator. By engineering long-range spin-spin interactions, we observe a spin kink splitting into a superposition of kinks at different positions, creating a ``Schrodinger kink'' that manifests non-locality and quantum interference. Furthermore, by preparing superposition states of neighboring kinks with different phases, we observe the propagation of the wave packet in different directions, thus unambiguously verifying the quantum coherence in the superposition states. Our work provides useful tools for non-equilibrium dynamics in quantum Kibble-Zurek physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15389v1-abstract-full').style.display = 'none'; document.getElementById('2410.15389v1-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> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 6 figures, already published in Science Advances</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Sci. Adv.10,eadr9527(2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.01206">arXiv:2410.01206</a> <span> [<a href="https://arxiv.org/pdf/2410.01206">pdf</a>, <a href="https://arxiv.org/format/2410.01206">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"> Polynomial-Time Preparation of Low-Temperature Gibbs States for 2D Toric Code </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ding%2C+Z">Zhiyan Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+L">Lin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Ruizhe 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="2410.01206v1-abstract-short" style="display: inline;"> We propose a polynomial-time algorithm for preparing the Gibbs state of the two-dimensional toric code Hamiltonian at any temperature, starting from any initial condition, significantly improving upon prior estimates that suggested exponential scaling with inverse temperature. Our approach combines the Lindblad dynamics using a local Davies generator with simple global jump operators to enable eff… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.01206v1-abstract-full').style.display = 'inline'; document.getElementById('2410.01206v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.01206v1-abstract-full" style="display: none;"> We propose a polynomial-time algorithm for preparing the Gibbs state of the two-dimensional toric code Hamiltonian at any temperature, starting from any initial condition, significantly improving upon prior estimates that suggested exponential scaling with inverse temperature. Our approach combines the Lindblad dynamics using a local Davies generator with simple global jump operators to enable efficient transitions between logical sectors. We also prove that the Lindblad dynamics with a digitally implemented low temperature local Davies generator is able to efficiently drive the quantum state towards the ground state manifold. Despite this progress, we explain why protecting quantum information in the 2D toric code with passive dynamics remains challenging. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.01206v1-abstract-full').style.display = 'none'; document.getElementById('2410.01206v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.14661">arXiv:2409.14661</a> <span> [<a href="https://arxiv.org/pdf/2409.14661">pdf</a>, <a href="https://arxiv.org/format/2409.14661">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"> Spectral signatures of the Markovian to Non-Markovian transition in open quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zeng-Zhao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yip%2C+C">Cho-Tung Yip</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo 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="2409.14661v2-abstract-short" style="display: inline;"> We present a new approach for investigating the Markovian to non-Markovian transition in quantum aggregates strongly coupled to a vibrational bath through the analysis of linear absorption spectra. Utilizing hierarchical algebraic equations in the frequency domain, we elucidate how these spectra can effectively reveal transitions between Markovian and non-Markovian regimes, driven by the complex i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14661v2-abstract-full').style.display = 'inline'; document.getElementById('2409.14661v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.14661v2-abstract-full" style="display: none;"> We present a new approach for investigating the Markovian to non-Markovian transition in quantum aggregates strongly coupled to a vibrational bath through the analysis of linear absorption spectra. Utilizing hierarchical algebraic equations in the frequency domain, we elucidate how these spectra can effectively reveal transitions between Markovian and non-Markovian regimes, driven by the complex interplay of dissipation, aggregate-bath coupling, and intra-aggregate dipole-dipole interactions. Our results demonstrate that reduced dissipation induces spectral peak splitting, signaling the emergence of bath-induced non-Markovian effects. The spectral peak splitting can also be driven by enhanced dipole-dipole interactions, although the underlying mechanism differs from that of dissipation-induced splitting. Additionally, with an increase in aggregate-bath coupling strength, initially symmetric or asymmetric peaks with varying spectral amplitudes may merge under weak dipole-dipole interactions, whereas strong dipole-dipole interactions are more likely to cause peak splitting. Moreover, we find that spectral features serve as highly sensitive indicators for distinguishing the geometric structures of aggregates, while also unveiling the critical role geometry plays in shaping non-Markovian behavior. This study not only deepens our understanding of the Markovian to non-Markovian transition but also provides a robust framework for optimizing and controlling quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.14661v2-abstract-full').style.display = 'none'; document.getElementById('2409.14661v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 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">13 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/2408.08365">arXiv:2408.08365</a> <span> [<a href="https://arxiv.org/pdf/2408.08365">pdf</a>, <a href="https://arxiv.org/format/2408.08365">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"> Coqa: Blazing Fast Compiler Optimizations for QAOA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Y">Yuchen Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yidong Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+J">Jinglei Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Y">Yuwei Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Boxi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+S">Siyuan Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+Z">Zhiding Liang</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="2408.08365v1-abstract-short" style="display: inline;"> The Quantum Approximate Optimization Algorithm (QAOA) is one of the most promising candidates for achieving quantum advantage over classical computers. However, existing compilers lack specialized methods for optimizing QAOA circuits. There are circuit patterns inside the QAOA circuits, and current quantum hardware has specific qubit connectivity topologies. Therefore, we propose Coqa to optimize… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08365v1-abstract-full').style.display = 'inline'; document.getElementById('2408.08365v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.08365v1-abstract-full" style="display: none;"> The Quantum Approximate Optimization Algorithm (QAOA) is one of the most promising candidates for achieving quantum advantage over classical computers. However, existing compilers lack specialized methods for optimizing QAOA circuits. There are circuit patterns inside the QAOA circuits, and current quantum hardware has specific qubit connectivity topologies. Therefore, we propose Coqa to optimize QAOA circuit compilation tailored to different types of quantum hardware. Our method integrates a linear nearest-neighbor (LNN) topology and efficiently map the patterns of QAOA circuits to the LNN topology by heuristically checking the interaction based on the weight of problem Hamiltonian. This approach allows us to reduce the number of SWAP gates during compilation, which directly impacts the circuit depth and overall fidelity of the quantum computation. By leveraging the inherent patterns in QAOA circuits, our approach achieves more efficient compilation compared to general-purpose compilers. With our proposed method, we are able to achieve an average of 30% reduction in gate count and a 39x acceleration in compilation time across our benchmarks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.08365v1-abstract-full').style.display = 'none'; document.getElementById('2408.08365v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 August, 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/2408.05435">arXiv:2408.05435</a> <span> [<a href="https://arxiv.org/pdf/2408.05435">pdf</a>, <a href="https://arxiv.org/format/2408.05435">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="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> SuperEncoder: Towards Universal Neural Approximate Quantum State Preparation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Yilun Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+B">Bingmeng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+W">Wenle Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xiwei Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Y">Yinhe Han</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ying 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="2408.05435v1-abstract-short" style="display: inline;"> Numerous quantum algorithms operate under the assumption that classical data has already been converted into quantum states, a process termed Quantum State Preparation (QSP). However, achieving precise QSP requires a circuit depth that scales exponentially with the number of qubits, making it a substantial obstacle in harnessing quantum advantage. Recent research suggests using a Parameterized Qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.05435v1-abstract-full').style.display = 'inline'; document.getElementById('2408.05435v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.05435v1-abstract-full" style="display: none;"> Numerous quantum algorithms operate under the assumption that classical data has already been converted into quantum states, a process termed Quantum State Preparation (QSP). However, achieving precise QSP requires a circuit depth that scales exponentially with the number of qubits, making it a substantial obstacle in harnessing quantum advantage. Recent research suggests using a Parameterized Quantum Circuit (PQC) to approximate a target state, offering a more scalable solution with reduced circuit depth compared to precise QSP. Despite this, the need for iterative updates of circuit parameters results in a lengthy runtime, limiting its practical application. In this work, we demonstrate that it is possible to leverage a pre-trained neural network to directly generate the QSP circuit for arbitrary quantum state, thereby eliminating the significant overhead of online iterations. Our study makes a steady step towards a universal neural designer for approximate QSP. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.05435v1-abstract-full').style.display = 'none'; document.getElementById('2408.05435v1-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 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/2408.04361">arXiv:2408.04361</a> <span> [<a href="https://arxiv.org/pdf/2408.04361">pdf</a>, <a href="https://arxiv.org/format/2408.04361">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"> Ultrabright-entanglement-based quantum key distribution over a 404-km-long optical fiber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhuang%2C+S">Shi-Chang Zhuang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+M">Ming-Yang Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Y">Yi-Xi Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hui-Nan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Guang-Bing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+Q">Quan Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+X">Xiu-Ping Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+H">Hao Qin</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Fei-Hu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</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="2408.04361v2-abstract-short" style="display: inline;"> The entangled photons are crucial resources for quantum communications and networking. Here, we present an ultra-bright polarization-entangled photon source based on a periodically poled lithium niobate waveguide designed for practical quantum communication networks. Using a 780 nm pump laser, the source achieves a pair generation rate of 2.4 $\times 10^{10}$ pairs/s/mW. This work has achieved a d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04361v2-abstract-full').style.display = 'inline'; document.getElementById('2408.04361v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.04361v2-abstract-full" style="display: none;"> The entangled photons are crucial resources for quantum communications and networking. Here, we present an ultra-bright polarization-entangled photon source based on a periodically poled lithium niobate waveguide designed for practical quantum communication networks. Using a 780 nm pump laser, the source achieves a pair generation rate of 2.4 $\times 10^{10}$ pairs/s/mW. This work has achieved a directly measured power of 17.9 nW in entangled photon generation with a 3.2 mW pump power. Based on this, we demonstrate the practicality of the source by conducting quantum key distribution experiments over long-distance fiber links, achieving the applicable secure key rates of up to 440.80 bits/s over 200 km with 62 dB loss and reaching a maximum secure key generation distance of 404 km. These results demonstrate the potential of wavelength-multiplexed polarization-entangled photon sources for high-speed, long-distance quantum communication, positioning them as key components for future large-scale quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04361v2-abstract-full').style.display = 'none'; document.getElementById('2408.04361v2-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 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">18 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/2408.03259">arXiv:2408.03259</a> <span> [<a href="https://arxiv.org/pdf/2408.03259">pdf</a>, <a href="https://arxiv.org/format/2408.03259">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="General Relativity and Quantum Cosmology">gr-qc</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</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.133.020201">10.1103/PhysRevLett.133.020201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Single-photon interference over 8.4 km urban atmosphere: towards testing quantum effects in curved spacetime with photons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hui-Nan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xiang You</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+J">Ji-Gang Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</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="2408.03259v2-abstract-short" style="display: inline;"> The emergence of quantum mechanics and general relativity has transformed our understanding of the natural world significantly. However, integrating these two theories presents immense challenges, and their interplay remains untested. Recent theoretical studies suggest that the single-photon interference covering huge space can effectively probe the interface between quantum mechanics and general… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.03259v2-abstract-full').style.display = 'inline'; document.getElementById('2408.03259v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.03259v2-abstract-full" style="display: none;"> The emergence of quantum mechanics and general relativity has transformed our understanding of the natural world significantly. However, integrating these two theories presents immense challenges, and their interplay remains untested. Recent theoretical studies suggest that the single-photon interference covering huge space can effectively probe the interface between quantum mechanics and general relativity. We developed an alternative design using unbalanced Michelson interferometers to address this and validated its feasibility over an 8.4 km free-space channel. Using a high-brightness single-photon source based on quantum dots, we demonstrated single-photon interference along this long-distance baseline. We achieved a phase measurement precision of 16.2 mrad, which satisfied the measurement requirements for a gravitational redshift at the geosynchronous orbit by five times the standard deviation. Our results confirm the feasibility of the single-photon version of the Colella-Overhauser-Werner experiment for testing the quantum effects in curved spacetime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.03259v2-abstract-full').style.display = 'none'; document.getElementById('2408.03259v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 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">22 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 133, 020201 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.08131">arXiv:2407.08131</a> <span> [<a href="https://arxiv.org/pdf/2407.08131">pdf</a>, <a href="https://arxiv.org/format/2407.08131">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.110.012609">10.1103/PhysRevA.110.012609 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Asynchronous measurement-device-independent quantum digital signatures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bian%2C+J">Jing-Wei Bian</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+Y">Yuan-Mei Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zeng-Bing 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="2407.08131v1-abstract-short" style="display: inline;"> Quantum digital signatures (QDSs), which distribute and measure quantum states by key generation protocols and then sign messages via classical data processing, are a key area of interest in quantum cryptography. However, the practical implementation of a QDS network has many challenges, including complex interference technical requirements, linear channel loss of quantum state transmission, and p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08131v1-abstract-full').style.display = 'inline'; document.getElementById('2407.08131v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.08131v1-abstract-full" style="display: none;"> Quantum digital signatures (QDSs), which distribute and measure quantum states by key generation protocols and then sign messages via classical data processing, are a key area of interest in quantum cryptography. However, the practical implementation of a QDS network has many challenges, including complex interference technical requirements, linear channel loss of quantum state transmission, and potential side-channel attacks on detectors. Here, we propose an asynchronous measurement-device-independent (MDI) QDS protocol with asynchronous two-photon interference strategy and one-time universal hashing method. The two-photon interference approach protects our protocol against all detector side-channel attacks and relaxes the difficulty of experiment implementation, while the asynchronous strategy effectively reduces the equivalent channel loss to its square root. Compared to previous MDI-QDS schemes, our protocol shows several orders of magnitude performance improvements and doubling of transmission distance when processing multi-bit messages. Our findings present an efficient and practical MDI-QDS scheme, paving the way for large-scale data processing with non-repudiation in quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.08131v1-abstract-full').style.display = 'none'; document.getElementById('2407.08131v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 5 figures, accepted by Physical Review A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 110, 012609 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.07513">arXiv:2407.07513</a> <span> [<a href="https://arxiv.org/pdf/2407.07513">pdf</a>, <a href="https://arxiv.org/format/2407.07513">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> High-rate quantum digital signatures network with integrated silicon photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yongqiang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+X">Xin Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+X">Xiao-Yu Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Zhengeng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+F">Feng Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+X">Xi Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</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="2407.07513v1-abstract-short" style="display: inline;"> The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and non-repudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07513v1-abstract-full').style.display = 'inline'; document.getElementById('2407.07513v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.07513v1-abstract-full" style="display: none;"> The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and non-repudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-scale deployment and reconfigurable networking construction. Here, we introduce and verify a chip-based QDS network, placing the complicated and expensive measurement devices in the central relay while each user needs only a low-cost transmitter. We demonstrate the network with a three-node setup using an integrated encoder chip and decoder chip. By developing a 1-decoy-state one-time universal hash-QDS protocol, we achieve a maximum signature rate of 0.0414 times per second for a 1 Mbit file over fiber distances up to 200 km, surpassing all current state-of-the-art QDS experiments. This study validates the feasibility of chip-based QDS, paving the way for large-scale deployment and integration with existing fiber infrastructure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07513v1-abstract-full').style.display = 'none'; document.getElementById('2407.07513v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">11 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/2407.06594">arXiv:2407.06594</a> <span> [<a href="https://arxiv.org/pdf/2407.06594">pdf</a>, <a href="https://arxiv.org/ps/2407.06594">ps</a>, <a href="https://arxiv.org/format/2407.06594">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"> A Randomized Method for Simulating Lindblad Equations and Thermal State Preparation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongrui Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+J">Jianfeng Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+L">Lexing Ying</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="2407.06594v2-abstract-short" style="display: inline;"> We study a qDRIFT-type randomized method to simulate Lindblad dynamics by decomposing its generator into an ensemble of Lindbladians, $\mathcal{L} = \sum_{a \in \mathcal{A}} \mathcal{L}_a$, where each $\mathcal{L}_a$ involves only a single jump operator. Assuming an efficient quantum simulation is available for the Hamiltonian evolution $e^{t\mathcal{L}_a}$, we implement a randomly sampled… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06594v2-abstract-full').style.display = 'inline'; document.getElementById('2407.06594v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06594v2-abstract-full" style="display: none;"> We study a qDRIFT-type randomized method to simulate Lindblad dynamics by decomposing its generator into an ensemble of Lindbladians, $\mathcal{L} = \sum_{a \in \mathcal{A}} \mathcal{L}_a$, where each $\mathcal{L}_a$ involves only a single jump operator. Assuming an efficient quantum simulation is available for the Hamiltonian evolution $e^{t\mathcal{L}_a}$, we implement a randomly sampled $\mathcal{L}_a$ at each time step according to a probability distribution $渭$ over the ensemble $\{\mathcal{L}_a\}_{a \in \mathcal{A}}$. This strategy reduces the quantum cost of simulating Lindblad dynamics, especially in quantum many-body systems with a large or even infinite number of jump operators. Our contributions are two-fold. First, we provide a detailed convergence analysis of the proposed randomized method, covering both average and typical algorithmic realizations. This analysis extends the known results for the random product formula from closed systems to open systems, ensuring rigorous performance guarantees. Second, based on the random product approximation, we derive a new quantum Gibbs sampler algorithm that utilizes jump operators sampled from a Clifford-random circuit. This generator (i) can be efficiently implemented using our randomized algorithm, and (ii) exhibits a spectral gap lower bound that depends on the spectrum of the Hamiltonian. Our results present a new instance of a class of Hamiltonians for which the thermal state can be efficiently prepared using a quantum Gibbs sampling algorithm. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06594v2-abstract-full').style.display = 'none'; document.getElementById('2407.06594v2-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">v1</span> submitted 9 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">Comments:</span> <span class="has-text-grey-dark mathjax">22 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/2407.04784">arXiv:2407.04784</a> <span> [<a href="https://arxiv.org/pdf/2407.04784">pdf</a>, <a href="https://arxiv.org/format/2407.04784">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum 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"> Cavity QED in a High NA Resonator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shadmany%2C+D">Danial Shadmany</a>, <a href="/search/quant-ph?searchtype=author&query=Kumar%2C+A">Aishwarya Kumar</a>, <a href="/search/quant-ph?searchtype=author&query=Soper%2C+A">Anna Soper</a>, <a href="/search/quant-ph?searchtype=author&query=Palm%2C+L">Lukas Palm</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+C">Chuan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Ando%2C+H">Henry Ando</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Taneja%2C+L">Lavanya Taneja</a>, <a href="/search/quant-ph?searchtype=author&query=Jaffe%2C+M">Matt Jaffe</a>, <a href="/search/quant-ph?searchtype=author&query=Schuster%2C+D">David Schuster</a>, <a href="/search/quant-ph?searchtype=author&query=Simon%2C+J">Jon Simon</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="2407.04784v1-abstract-short" style="display: inline;"> From fundamental studies of light-matter interaction to applications in quantum networking and sensing, cavity quantum electrodynamics (QED) provides a platform-crossing toolbox to control interactions between atoms and photons. The coherence of such interactions is determined by the product of the single-pass atomic absorption and the number of photon round-trips. Reducing the cavity loss has ena… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.04784v1-abstract-full').style.display = 'inline'; document.getElementById('2407.04784v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.04784v1-abstract-full" style="display: none;"> From fundamental studies of light-matter interaction to applications in quantum networking and sensing, cavity quantum electrodynamics (QED) provides a platform-crossing toolbox to control interactions between atoms and photons. The coherence of such interactions is determined by the product of the single-pass atomic absorption and the number of photon round-trips. Reducing the cavity loss has enabled resonators supporting nearly 1-million optical roundtrips at the expense of severely limited optical material choices and increased alignment sensitivity. The single-pass absorption probability can be increased through the use of near-concentric, fiber or nanophotonic cavities, which reduce the mode waists at the expense of constrained optical access and exposure to surface fields. Here we present a new high numerical-aperture, lens-based resonator that pushes the single-atom-single-photon absorption probability per round trip close to its fundamental limit by reducing the mode size at the atom below a micron while keeping the atom mm-to-cm away from all optics. This resonator provides strong light-matter coupling in a cavity where the light circulates only ~ 10 times. We load a single 87Rb atom into such a cavity, observe strong coupling, demonstrate cavity-enhanced atom detection with imaging fidelity of 99.55(6) percent and survival probability of 99.89(4) percent in 130 microseconds, and leverage this new platform for a time-resolved exploration of cavity cooling. The resonator's loss-resilience paves the way to coupling of atoms to nonlinear and adaptive optical elements and provides a minimally invasive route to readout of defect centers. Introduction of intra-cavity imaging systems will enable the creation of cavity arrays compatible with Rydberg atom array computing technologies, vastly expanding the applicability of the cavity QED toolbox. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.04784v1-abstract-full').style.display = 'none'; document.getElementById('2407.04784v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 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/2407.03609">arXiv:2407.03609</a> <span> [<a href="https://arxiv.org/pdf/2407.03609">pdf</a>, <a href="https://arxiv.org/ps/2407.03609">ps</a>, <a href="https://arxiv.org/format/2407.03609">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"> Continuous-variable quantum digital signatures against coherent attacks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yi-Fan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wen-Bo Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zeng-Bing 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="2407.03609v1-abstract-short" style="display: inline;"> Quantum digital signatures (QDS), which utilize correlated bit strings among sender and recipients, guarantee the authenticity, integrity and non-repudiation of classical messages based on quantum laws. Continuous-variable (CV) quantum protocol with heterodyne and homodyne measurement has obvious advantages of low-cost implementation and easy wavelength division multiplexing. However, security ana… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03609v1-abstract-full').style.display = 'inline'; document.getElementById('2407.03609v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.03609v1-abstract-full" style="display: none;"> Quantum digital signatures (QDS), which utilize correlated bit strings among sender and recipients, guarantee the authenticity, integrity and non-repudiation of classical messages based on quantum laws. Continuous-variable (CV) quantum protocol with heterodyne and homodyne measurement has obvious advantages of low-cost implementation and easy wavelength division multiplexing. However, security analyses in previous researches are limited to the proof against collective attacks in finite-size scenarios. Moreover, existing multi-bit CV QDS schemes have primarily focused on adapting single-bit protocols for simplicity of security proof, often sacrificing signature efficiency. Here, we introduce a CV QDS protocol designed to withstand general coherent attacks through the use of a cutting-edge fidelity test function, while achieving high signature efficiency by employing a refined one-time universal hashing signing technique. Our protocol is proved to be robust against finite-size effects and excess noise in quantum channels. In simulation, results demonstrate a significant reduction of over 6 orders of magnitude in signature length for a megabit message signing task compared to existing CV QDS protocols and this advantage expands as the message size grows. Our work offers a solution with enhanced security and efficiency, paving the way for large-scale deployment of CV QDS in future quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03609v1-abstract-full').style.display = 'none'; document.getElementById('2407.03609v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 8 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/2407.01429">arXiv:2407.01429</a> <span> [<a href="https://arxiv.org/pdf/2407.01429">pdf</a>, <a href="https://arxiv.org/format/2407.01429">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"> Generalized quantum repeater graph states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bikun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Goodenough%2C+K">Kenneth Goodenough</a>, <a href="/search/quant-ph?searchtype=author&query=Rozp%C4%99dek%2C+F">Filip Rozp臋dek</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.01429v1-abstract-short" style="display: inline;"> All-photonic quantum repeaters are essential for establishing long-range quantum entanglement. Within repeater nodes, reliably performing entanglement swapping is a key component of scalable quantum communication. To tackle the challenge of probabilistic Bell state measurement in linear optics, which often leads to information loss, various approaches have been proposed to ensure the loss toleranc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.01429v1-abstract-full').style.display = 'inline'; document.getElementById('2407.01429v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.01429v1-abstract-full" style="display: none;"> All-photonic quantum repeaters are essential for establishing long-range quantum entanglement. Within repeater nodes, reliably performing entanglement swapping is a key component of scalable quantum communication. To tackle the challenge of probabilistic Bell state measurement in linear optics, which often leads to information loss, various approaches have been proposed to ensure the loss tolerance of distributing a single ebit. We have generalized previous work regarding repeater graph states with elaborate connectivity, enabling the efficient establishment of exploitable ebits at a finite rate with high probability. We demonstrate that our new scheme significantly outperforms the previous work with much flexibility and discuss the generation overhead of such resource states. These findings offer new insights into the scalability and reliability of loss-tolerant quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.01429v1-abstract-full').style.display = 'none'; document.getElementById('2407.01429v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 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/2406.10715">arXiv:2406.10715</a> <span> [<a href="https://arxiv.org/pdf/2406.10715">pdf</a>, <a href="https://arxiv.org/format/2406.10715">other</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"> Chip-scale generation of 60-mode continuous-variable cluster states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Ze Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+K">Kangkang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yue Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+X">Xin Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Y">Yinke Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Jing%2C+B">Boxuan Jing</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+F">Fengxiao Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jincheng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zhilin Li</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+Q">Qihuang Gong</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Q">Qiongyi He</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bei-Bei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Q">Qi-Fan Yang</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="2406.10715v1-abstract-short" style="display: inline;"> Increasing the number of entangled entities is crucial for achieving exponential computational speedups and secure quantum networks. Despite recent progress in generating large-scale entanglement through continuous-variable (CV) cluster states, translating these technologies to photonic chips has been hindered by decoherence, limiting the number of entangled entities to 8. Here, we demonstrate 60-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.10715v1-abstract-full').style.display = 'inline'; document.getElementById('2406.10715v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.10715v1-abstract-full" style="display: none;"> Increasing the number of entangled entities is crucial for achieving exponential computational speedups and secure quantum networks. Despite recent progress in generating large-scale entanglement through continuous-variable (CV) cluster states, translating these technologies to photonic chips has been hindered by decoherence, limiting the number of entangled entities to 8. Here, we demonstrate 60-mode CVcluster states in a chip-based optical microresonator pumped by chromatic lasers. Resonantly-enhanced four-wave mixing processes establish entanglement between equidistant spectral quantum modes (qumodes), forming a quantum analogue of optical frequency combs. Decoherence is minimized to achieve unprecedented two-mode raw squeezing (>3 dB) from a chip. Using bichromatic and trichromatic pump lasers, we realize one- and two-dimensional cluster states with up to 60 qumodes. Our work provides a compact and scalable platform for constructing large-scale entangled quantum resources, which are appealing for performing computational and communicational tasks with quantum advantages. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.10715v1-abstract-full').style.display = 'none'; document.getElementById('2406.10715v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.09115">arXiv:2406.09115</a> <span> [<a href="https://arxiv.org/pdf/2406.09115">pdf</a>, <a href="https://arxiv.org/ps/2406.09115">ps</a>, <a href="https://arxiv.org/format/2406.09115">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Dynamical Systems">math.DS</span> </div> </div> <p class="title is-5 mathjax"> Quantum space-time Poincar茅 inequality for Lindblad dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+J">Jianfeng Lu</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="2406.09115v2-abstract-short" style="display: inline;"> We investigate the mixing properties of primitive hypocoercive Lindblad dynamics. By extending the variational framework originally developed for underdamped Langevin dynamics, we derive fully explicit and constructive exponential decay estimates for the convergence in the noncommutative $L^2$-norm. Our analysis relies on establishing a quantum analog of space-time Poincar茅 inequalities. To comple… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.09115v2-abstract-full').style.display = 'inline'; document.getElementById('2406.09115v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.09115v2-abstract-full" style="display: none;"> We investigate the mixing properties of primitive hypocoercive Lindblad dynamics. By extending the variational framework originally developed for underdamped Langevin dynamics, we derive fully explicit and constructive exponential decay estimates for the convergence in the noncommutative $L^2$-norm. Our analysis relies on establishing a quantum analog of space-time Poincar茅 inequalities. To complement these hypocoercive estimates, we also analyze the limiting behavior of the spectral gap for Lindblad dynamics with a large coherent contribution, providing sharper convergence rate estimates in this asymptotic regime. A number of concrete examples are provided as applications of our theoretical results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.09115v2-abstract-full').style.display = 'none'; document.getElementById('2406.09115v2-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">v1</span> submitted 13 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.02482">arXiv:2406.02482</a> <span> [<a href="https://arxiv.org/pdf/2406.02482">pdf</a>, <a href="https://arxiv.org/format/2406.02482">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.110.205108">10.1103/PhysRevB.110.205108 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Three-dimensional fracton topological orders with boundary Toeplitz braiding </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo-Xi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yao Zhou</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="2406.02482v4-abstract-short" style="display: inline;"> In this paper, we theoretically study a class of 3D non-liquid states that show exotic boundary phenomena in the thermodynamical limit. More concretely, we focus on a class of 3D fracton topological orders formed via stacking 2D twisted $\mathbb{Z}_N$ topologically ordered layers along $z$-direction. Nearby layers are coupled while maintaining translation symmetry along $z$ direction. The ef… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02482v4-abstract-full').style.display = 'inline'; document.getElementById('2406.02482v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.02482v4-abstract-full" style="display: none;"> In this paper, we theoretically study a class of 3D non-liquid states that show exotic boundary phenomena in the thermodynamical limit. More concretely, we focus on a class of 3D fracton topological orders formed via stacking 2D twisted $\mathbb{Z}_N$ topologically ordered layers along $z$-direction. Nearby layers are coupled while maintaining translation symmetry along $z$ direction. The effective field theory is given by the infinite-component Chern-Simons (iCS) field theory, with an integer-valued symmetric block-tridiagonal Toeplitz $K$-matrix whose size is thermodynamically large. With open boundary conditions (OBC) along $z$, certain choice of $K$-matrices exhibits exotic boundary ``Toeplitz braiding'', where the mutual braiding phase angle between two anyons at opposite boundaries oscillates and remains non-zero in the thermodynamic limit. In contrast, in trivial case, the mutual braiding phase angle decays exponentially to zero in the thermodynamical limit. As a necessary condition, this phenomenon requires the existence of boundary zero modes in the $K$-matrix spectrum under OBC. We categorize nontrivial $K$-matrices into two distinct types. Each type-I possesses two boundary zero modes, whereas each type-II possesses only one boundary zero mode. Interestingly, the integer-valued Hamiltonian matrix of the familiar 1D SSH can be used as a non-trivial $K$-matrix. Importantly, since large-gauge-invariance ensures integer quantized $K$-matrix entries, global symmetries are not needed to protect these zero modes. We also present numerical simulation as well as finite size scaling, further confirming the above analytical results. Symmetry fractionalization is also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02482v4-abstract-full').style.display = 'none'; document.getElementById('2406.02482v4-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 110, 205108 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.20570">arXiv:2405.20570</a> <span> [<a href="https://arxiv.org/pdf/2405.20570">pdf</a>, <a href="https://arxiv.org/ps/2405.20570">ps</a>, <a href="https://arxiv.org/format/2405.20570">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/10.1364/OE.527497">10.1364/OE.527497 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Generation of subnatural-linewidth orbital angular momentum entangled biphotons using a single driving laser in hot atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ma%2C+J">Jiaheng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">Chengyuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bingbing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Ye Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jinwen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xin Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+S">Shuwei Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+H">Hong Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+F">Fuli 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="2405.20570v1-abstract-short" style="display: inline;"> Orbital angular momentum (OAM) entangled photon pairs with narrow bandwidths play a crucial role in the interaction of light and quantum states of matter. In this article, we demonstrate an approach for generating OAM entangled photon pairs with a narrow bandwidth by using a single driving beam in a $^{85}$Rb atomic vapor cell. This single driving beam is able to simultaneously couple two atomic t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.20570v1-abstract-full').style.display = 'inline'; document.getElementById('2405.20570v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.20570v1-abstract-full" style="display: none;"> Orbital angular momentum (OAM) entangled photon pairs with narrow bandwidths play a crucial role in the interaction of light and quantum states of matter. In this article, we demonstrate an approach for generating OAM entangled photon pairs with a narrow bandwidth by using a single driving beam in a $^{85}$Rb atomic vapor cell. This single driving beam is able to simultaneously couple two atomic transitions and directly generate OAM entangled biphotons by leveraging the OAM conservation law through the spontaneous four-wave mixing (SFWM) process. The photon pairs exhibit a maximum cross-correlation function value of 27.7 and a linewidth of 4 MHz. The OAM entanglement is confirmed through quantum state tomography, revealing a fidelity of 95.7\% and a concurrence of 0.926 when compared to the maximally entangled state. Our scheme is notably simpler than previously proposed schemes and represents the first demonstration of generating subnatural-linewidth entangled photon pairs in hot atomic systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.20570v1-abstract-full').style.display = 'none'; document.getElementById('2405.20570v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Optics Express 32, 23026-23035 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.15236">arXiv:2405.15236</a> <span> [<a href="https://arxiv.org/pdf/2405.15236">pdf</a>, <a href="https://arxiv.org/format/2405.15236">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"> Detecting Errors in a Quantum Network with Pauli Checks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gonzales%2C+A">Alvin Gonzales</a>, <a href="/search/quant-ph?searchtype=author&query=Dilley%2C+D">Daniel Dilley</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bikun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+L">Liang Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Saleem%2C+Z+H">Zain H. Saleem</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="2405.15236v3-abstract-short" style="display: inline;"> We apply the quantum error detection scheme Pauli check sandwiching (PCS) to quantum networks by turning it into a distributed multiparty protocol. PCS is a distance 1 code and requires less resource overhead than standard quantum error correction and detection methods. We provide analytical equations for the final fidelity and postselection rate. We also introduce a recursive version of PCS for e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.15236v3-abstract-full').style.display = 'inline'; document.getElementById('2405.15236v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.15236v3-abstract-full" style="display: none;"> We apply the quantum error detection scheme Pauli check sandwiching (PCS) to quantum networks by turning it into a distributed multiparty protocol. PCS is a distance 1 code and requires less resource overhead than standard quantum error correction and detection methods. We provide analytical equations for the final fidelity and postselection rate. We also introduce a recursive version of PCS for entanglement purification that only scales polynomially in the resources required as a function of the number of recursions. The recursive PCS scheme generates a family of distance 2 quantum codes. Our analytical results are benchmarked against BBPSSW in comparable scenarios. We also perform simulations with noisy gates for entanglement swapping and attain substantial fidelity improvements. Lastly, we discuss various setups and graph state properties of PCS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.15236v3-abstract-full').style.display = 'none'; document.getElementById('2405.15236v3-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">v1</span> submitted 24 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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 are 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/2405.15148">arXiv:2405.15148</a> <span> [<a href="https://arxiv.org/pdf/2405.15148">pdf</a>, <a href="https://arxiv.org/ps/2405.15148">ps</a>, <a href="https://arxiv.org/format/2405.15148">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"> Dynamically corrected gates in silicon singlet-triplet spin qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Walelign%2C+H+Y">Habitamu Y. Walelign</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+X">Xinxin Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bikun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Barnes%2C+E">Edwin Barnes</a>, <a href="/search/quant-ph?searchtype=author&query=Nichol%2C+J+M">John M. Nichol</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="2405.15148v2-abstract-short" style="display: inline;"> Fault-tolerant quantum computation requires low physical-qubit gate errors. Many approaches exist to reduce gate errors, including both hardware- and control-optimization strategies. Dynamically corrected gates are designed to cancel specific errors and offer the potential for high-fidelity gates, but they have yet to be implemented in singlet-triplet spin qubits in semiconductor quantum dots, due… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.15148v2-abstract-full').style.display = 'inline'; document.getElementById('2405.15148v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.15148v2-abstract-full" style="display: none;"> Fault-tolerant quantum computation requires low physical-qubit gate errors. Many approaches exist to reduce gate errors, including both hardware- and control-optimization strategies. Dynamically corrected gates are designed to cancel specific errors and offer the potential for high-fidelity gates, but they have yet to be implemented in singlet-triplet spin qubits in semiconductor quantum dots, due in part to the stringent control constraints in these systems. In this work, we experimentally implement dynamically corrected gates designed to mitigate hyperfine noise in a singlet-triplet qubit realized in a Si/SiGe double quantum dot. The corrected gates reduce infidelities by about a factor of three, resulting in gate fidelities above 0.99 for both identity and Hadamard gates. The gate performances depend sensitively on pulse distortions, and their specific performance reveals an unexpected distortion in our experimental setup. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.15148v2-abstract-full').style.display = 'none'; document.getElementById('2405.15148v2-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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 including supplementary materials. 10 figures including those in the 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/2404.07509">arXiv:2404.07509</a> <span> [<a href="https://arxiv.org/pdf/2404.07509">pdf</a>, <a href="https://arxiv.org/format/2404.07509">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/10.1016/j.optlastec.2024.111558">10.1016/j.optlastec.2024.111558 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiparameter cascaded quantum interferometer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Baihong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qi-qi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhuo-zhuo Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Penglong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+C">Changhua Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+B">Boxin Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhai%2C+Y">Yiwei Zhai</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xiaofei 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="2404.07509v3-abstract-short" style="display: inline;"> We theoretically propose a multiparameter cascaded quantum interferometer in which a two-input and two-output setup is obtained by concatenating 50:50 beam splitters with $n$ independent and adjustable time delays. A general method for deriving the coincidence probability of such an interferometer is given based on the linear transformation of the matrix of beam splitters. As examples, we analyze… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.07509v3-abstract-full').style.display = 'inline'; document.getElementById('2404.07509v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.07509v3-abstract-full" style="display: none;"> We theoretically propose a multiparameter cascaded quantum interferometer in which a two-input and two-output setup is obtained by concatenating 50:50 beam splitters with $n$ independent and adjustable time delays. A general method for deriving the coincidence probability of such an interferometer is given based on the linear transformation of the matrix of beam splitters. As examples, we analyze the interference characteristics of one-, two- and three-parameter cascaded quantum interferometers with different frequency correlations and input states. Some typical interferograms of such interferometers are provided to reveal richer and more complicated two-photon interference phenomena. This work offers a general theoretical framework for designing versatile quantum interferometers and provides a convenient method for deriving the coincidence probabilities involved. In principle, arbitrary two-input and two-output experimental setups can be designed with the framework. Potential applications can be found in the complete spectral characterization of two-photon states, multiparameter estimation, and quantum metrology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.07509v3-abstract-full').style.display = 'none'; document.getElementById('2404.07509v3-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">v1</span> submitted 11 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">16 pages, 10 figures. arXiv admin note: text overlap with arXiv:2305.13734</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Optics & Laser Technology 181 (2025) 111558 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.05998">arXiv:2404.05998</a> <span> [<a href="https://arxiv.org/pdf/2404.05998">pdf</a>, <a href="https://arxiv.org/format/2404.05998">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"> Efficient quantum Gibbs samplers with Kubo--Martin--Schwinger detailed balance condition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ding%2C+Z">Zhiyan Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+L">Lin Lin</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="2404.05998v5-abstract-short" style="display: inline;"> Lindblad dynamics and other open-system dynamics provide a promising path towards efficient Gibbs sampling on quantum computers. In these proposals, the Lindbladian is obtained via an algorithmic construction akin to designing an artificial thermostat in classical Monte Carlo or molecular dynamics methods, rather than treated as an approximation to weakly coupled system-bath unitary dynamics. Rece… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.05998v5-abstract-full').style.display = 'inline'; document.getElementById('2404.05998v5-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.05998v5-abstract-full" style="display: none;"> Lindblad dynamics and other open-system dynamics provide a promising path towards efficient Gibbs sampling on quantum computers. In these proposals, the Lindbladian is obtained via an algorithmic construction akin to designing an artificial thermostat in classical Monte Carlo or molecular dynamics methods, rather than treated as an approximation to weakly coupled system-bath unitary dynamics. Recently, Chen, Kastoryano, and Gily茅n (arXiv:2311.09207) introduced the first efficiently implementable Lindbladian satisfying the Kubo--Martin--Schwinger (KMS) detailed balance condition, which ensures that the Gibbs state is a fixed point of the dynamics and is applicable to non-commuting Hamiltonians. This Gibbs sampler uses a continuously parameterized set of jump operators, and the energy resolution required for implementing each jump operator depends only logarithmically on the precision and the mixing time. In this work, we build upon the structural characterization of KMS detailed balanced Lindbladians by Fagnola and Umanit脿, and develop a family of efficient quantum Gibbs samplers using a finite set of jump operators (the number can be as few as one), \re{akin to the classical Markov chain-based sampling algorithm. Compared to the existing works, our quantum Gibbs samplers have a comparable quantum simulation cost but with greater design flexibility and a much simpler implementation and error analysis.} Moreover, it encompasses the construction of Chen, Kastoryano, and Gily茅n as a special instance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.05998v5-abstract-full').style.display = 'none'; document.getElementById('2404.05998v5-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.14476">arXiv:2403.14476</a> <span> [<a href="https://arxiv.org/pdf/2403.14476">pdf</a>, <a href="https://arxiv.org/format/2403.14476">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-024-00870-5">10.1038/s41534-024-00870-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Loss-induced quantum nonreciprocity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Baijun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zuo%2C+Y">Yunlan Zuo</a>, <a href="/search/quant-ph?searchtype=author&query=Kuang%2C+L">Le-Man Kuang</a>, <a href="/search/quant-ph?searchtype=author&query=Jing%2C+H">Hui Jing</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+C">Chaohong 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="2403.14476v1-abstract-short" style="display: inline;"> Attribute to their robustness against loss and external noise, nonreciprocal photonic devices hold great promise for applications in quantum information processing. Recent advancements have demonstrated that nonreciprocal optical transmission in linear systems can be achieved through the strategic introduction of loss. However, a crucial question remains unanswered: can loss be harnessed as a reso… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.14476v1-abstract-full').style.display = 'inline'; document.getElementById('2403.14476v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.14476v1-abstract-full" style="display: none;"> Attribute to their robustness against loss and external noise, nonreciprocal photonic devices hold great promise for applications in quantum information processing. Recent advancements have demonstrated that nonreciprocal optical transmission in linear systems can be achieved through the strategic introduction of loss. However, a crucial question remains unanswered: can loss be harnessed as a resource for generating nonreciprocal quantum correlations? Here, we take a counterintuitive stance by engineering loss to generate a novel form of nonreciprocal quantum correlations, termed nonreciprocal photon blockade. We examine a dissipative three-cavity system comprising two nonlinear cavities and a linear cavity. The interplay of loss and nonlinearity leads to a robust nonreciprocal single- and two-photon blockade, facilitated by destructive quantum interference. Furthermore, we demonstrate the tunability of this nonreciprocal photon blockade by manipulating the relative phase between the two nonlinear cavities. Remarkably, this allows for the reversal of the direction of nonreciprocity. Our study not only sheds new light on the concept of loss-engineered quantum nonreciprocity but also opens up a unique pathway for the design of quantum nonreciprocal photonic devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.14476v1-abstract-full').style.display = 'none'; document.getElementById('2403.14476v1-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 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Inf 10, 75 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.11441">arXiv:2403.11441</a> <span> [<a href="https://arxiv.org/pdf/2403.11441">pdf</a>, <a href="https://arxiv.org/format/2403.11441">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/sciadv.adp2877">10.1126/sciadv.adp2877 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Quantum Byzantine Agreement on a Three-User Quantum Network with Integrated Photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jing%2C+X">Xu Jing</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+C">Cheng Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Weng%2C+C">Chen-Xun Weng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zhe Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">Chen-Quan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+J">Jie Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+X">Xiao-Wen Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Kong%2C+Y">Yue-Chan Kong</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Tang-Sheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+D">Dong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+B">Bin Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+L">Liang-Liang Lu</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="2403.11441v2-abstract-short" style="display: inline;"> Quantum communication networks are crucial for both secure communication and cryptographic networked tasks. Building quantum communication networks in a scalable and cost-effective way is essential for their widespread adoption, among which a stable and miniaturized high-quality quantum light source is a key component. Here, we establish a complete polarization entanglement-based fully connected n… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.11441v2-abstract-full').style.display = 'inline'; document.getElementById('2403.11441v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.11441v2-abstract-full" style="display: none;"> Quantum communication networks are crucial for both secure communication and cryptographic networked tasks. Building quantum communication networks in a scalable and cost-effective way is essential for their widespread adoption, among which a stable and miniaturized high-quality quantum light source is a key component. Here, we establish a complete polarization entanglement-based fully connected network, which features an ultrabright integrated Bragg reflection waveguide quantum source, managed by an untrusted service provider, and a streamlined polarization analysis module, which requires only one single-photon detector for each end user. We perform a continuously working quantum entanglement distribution and create correlated bit strings between users. Within the framework of one-time universal hashing, we provide the first experimental implementation of source-independent quantum digital signatures using imperfect keys circumventing the necessity for private amplification. More importantly, we further beat the 1/3 fault-tolerance bound in Byzantine agreement, achieving unconditional security without relying on sophisticated techniques. Our results offer an affordable and practical route for addressing consensus challenges within the emerging quantum network landscape. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.11441v2-abstract-full').style.display = 'none'; document.getElementById('2403.11441v2-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Advances 10, eadp2877 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.10657">arXiv:2403.10657</a> <span> [<a href="https://arxiv.org/pdf/2403.10657">pdf</a>, <a href="https://arxiv.org/format/2403.10657">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.110.033715">10.1103/PhysRevA.110.033715 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Fisher information and polaron picture for identification of transition coupling in quantum Rabi model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ying%2C+Z">Zu-Jian Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wen-Long Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo-Jian 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="2403.10657v1-abstract-short" style="display: inline;"> The quantum Rabi model (QRM) is a fundamental model for light-matter interactions. A fascinating feature of the QRM is that it manifests a quantum phase transition which is applicable for critical quantum metrology (CQM). Effective application for CQM needs the exact location of the transition point, however the conventional expression for the transition coupling is only valid in the extreme limit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.10657v1-abstract-full').style.display = 'inline'; document.getElementById('2403.10657v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.10657v1-abstract-full" style="display: none;"> The quantum Rabi model (QRM) is a fundamental model for light-matter interactions. A fascinating feature of the QRM is that it manifests a quantum phase transition which is applicable for critical quantum metrology (CQM). Effective application for CQM needs the exact location of the transition point, however the conventional expression for the transition coupling is only valid in the extreme limit of low frequency, while apart from zero frequency an accurate location is still lacking. In the present work we conversely use the quantum Fisher information (QFI) in the CQM to identify the transition coupling, which finds out that transition coupling indeed much deviates from the conventional one once a finite frequency is turned on. Polaron picture is applied to analytically reproduce the numeric QFI. An accurate expression for the transition coupling is obtained by the inspiration from the fractional-power-law effect of polaron frequency renormalization. From the QFI in the polaron picture we find that the transition occurs around a point where the effective velocity and the susceptibility of the single-photon absorption rate reach maximum. Our result provides an accurate reference of transition couplings for quantum metrology at non-zero frequencies. The formulation of the QFI in the polaron picture also prepares an analytic method with an accurate compensation for the parameter regime difficult to access for the numerics. Besides the integer/fractional power law analysis to extract the underlying physics of transition, the QFI/velocity relation may also add some insight in bridging the QFI and transition observables. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.10657v1-abstract-full').style.display = 'none'; document.getElementById('2403.10657v1-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 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">14 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review A 110, 033715 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.17163">arXiv:2311.17163</a> <span> [<a href="https://arxiv.org/pdf/2311.17163">pdf</a>, <a href="https://arxiv.org/format/2311.17163">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"> A Site-Resolved 2D Quantum Simulator with Hundreds of Trapped Ions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S+-">S. -A. Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y+-">Y. -K. Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+J">J. Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">L. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Lian%2C+W+-">W. -Q. Lian</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+R">R. Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Y. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+R+-">R. -Y. Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Yi%2C+Y+-">Y. -J. Yi</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y+-">Y. -L. Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B+-">B. -W. Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+Y+-">Y. -H. Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y+-">Y. -Z. Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+W+-">W. -X. Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">C. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Qi%2C+B+-">B. -X. Qi</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z+-">Z. -C. Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+L">L. He</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+L+-">L. -M. Duan</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="2311.17163v2-abstract-short" style="display: inline;"> A large qubit capacity and an individual readout capability are two crucial requirements for large-scale quantum computing and simulation. As one of the leading physical platforms for quantum information processing, the ion trap has achieved quantum simulation of tens of ions with site-resolved readout in 1D Paul trap, and that of hundreds of ions with global observables in 2D Penning trap. Howeve… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.17163v2-abstract-full').style.display = 'inline'; document.getElementById('2311.17163v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.17163v2-abstract-full" style="display: none;"> A large qubit capacity and an individual readout capability are two crucial requirements for large-scale quantum computing and simulation. As one of the leading physical platforms for quantum information processing, the ion trap has achieved quantum simulation of tens of ions with site-resolved readout in 1D Paul trap, and that of hundreds of ions with global observables in 2D Penning trap. However, integrating these two features into a single system is still very challenging. Here we report the stable trapping of 512 ions in a 2D Wigner crystal and the sideband cooling of their transverse motion. We demonstrate the quantum simulation of long-range quantum Ising models with tunable coupling strengths and patterns, with or without frustration, using 300 ions. Enabled by the site resolution in the single-shot measurement, we observe rich spatial correlation patterns in the quasi-adiabatically prepared ground states, which allows us to verify quantum simulation results by comparing with the calculated collective phonon modes and with classical simulated annealing. We further probe the quench dynamics of the Ising model in a transverse field to demonstrate quantum sampling tasks. Our work paves the way for simulating classically intractable quantum dynamics and for running NISQ algorithms using 2D ion trap quantum simulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.17163v2-abstract-full').style.display = 'none'; document.getElementById('2311.17163v2-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.08164">arXiv:2311.08164</a> <span> [<a href="https://arxiv.org/pdf/2311.08164">pdf</a>, <a href="https://arxiv.org/format/2311.08164">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"> Full characterization of biphotons with a generalized quantum interferometer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Baihong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+C">Changhua Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+B">Boxin Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xiaofei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+R">Rui-Bo Jin</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="2311.08164v3-abstract-short" style="display: inline;"> Entangled photons (biphotons) in the time-frequency degree of freedom play a crucial role in both foundational physics and advanced quantum technologies. Fully characterizing them poses a key scientific challenge. Here, we propose a theoretical approach to achieving the complete tomography of biphotons by introducing a frequency shift in one arm of the combination interferometer. Our method, a gen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08164v3-abstract-full').style.display = 'inline'; document.getElementById('2311.08164v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.08164v3-abstract-full" style="display: none;"> Entangled photons (biphotons) in the time-frequency degree of freedom play a crucial role in both foundational physics and advanced quantum technologies. Fully characterizing them poses a key scientific challenge. Here, we propose a theoretical approach to achieving the complete tomography of biphotons by introducing a frequency shift in one arm of the combination interferometer. Our method, a generalized combination interferometer, enables the reconstruction of the full complex joint spectral amplitude associated with both frequency sum and difference in a single interferometer. In contrast, the generalized Hong-Ou-Mandel and N00N state interferometers only allow for the partial tomography of biphotons, either in frequency difference or frequency sum. This provides an alternative method for full characterization of an arbitrary two-photon state with exchange symmetry and holds potential for applications in high-dimensional quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08164v3-abstract-full').style.display = 'none'; document.getElementById('2311.08164v3-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 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 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/2311.06435">arXiv:2311.06435</a> <span> [<a href="https://arxiv.org/pdf/2311.06435">pdf</a>, <a href="https://arxiv.org/format/2311.06435">other</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 class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-023-43393-x">10.1038/s41467-023-43393-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optomechanical ring resonator for efficient microwave-optical frequency conversion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+I">I-Tung Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bingzhao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+S">Seokhyeong Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Chakravarthi%2C+S">Srivatsa Chakravarthi</a>, <a href="/search/quant-ph?searchtype=author&query=Fu%2C+K">Kai-Mei Fu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Mo 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="2311.06435v2-abstract-short" style="display: inline;"> Phonons traveling in solid-state devices are emerging as a universal excitation that can couple to different physical systems through mechanical interaction. At microwave frequencies and in solid-state materials, phonons have a similar wavelength to optical photons, enabling them to interact efficiently with light and produce strong optomechanical effects that are highly desirable for classical an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.06435v2-abstract-full').style.display = 'inline'; document.getElementById('2311.06435v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.06435v2-abstract-full" style="display: none;"> Phonons traveling in solid-state devices are emerging as a universal excitation that can couple to different physical systems through mechanical interaction. At microwave frequencies and in solid-state materials, phonons have a similar wavelength to optical photons, enabling them to interact efficiently with light and produce strong optomechanical effects that are highly desirable for classical and quantum signal transduction between optical and microwave. It becomes conceivable to build optomechanical integrated circuits (OMIC) that guide both photons and phonons and interconnect discrete photonic and phononic devices. Here, we demonstrate an OMIC including an optomechanical ring resonator (OMR), in which infrared photons and GHz phonons co-resonate to induce significantly enhanced interconversion. The OMIC is built on a hybrid platform where wide bandgap semiconductor gallium phosphide (GaP) is used as the waveguiding material and piezoelectric zinc oxide (ZnO) is used for phonon generation. The OMR features photonic and phononic quality factors of $>1\times10^5$ and $3.2\times10^3$, respectively, and resonantly enhances the optomechanical conversion between photonic modes to achieve an internal conversion efficiency $畏_i=(2.1\pm0.1)%$ and a total device efficiency $畏_{tot}=0.57\times10^{-6}$ at a low acoustic pump power of 1.6 mW. The efficient conversion in OMICs enables microwave-optical transduction for many applications in quantum information processing and microwave photonics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.06435v2-abstract-full').style.display = 'none'; document.getElementById('2311.06435v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.12893">arXiv:2310.12893</a> <span> [<a href="https://arxiv.org/pdf/2310.12893">pdf</a>, <a href="https://arxiv.org/format/2310.12893">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="Cryptography and Security">cs.CR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</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.133.120602">10.1103/PhysRevLett.133.120602 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Blind quantum machine learning with quantum bipartite correlator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Changhao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Boning Li</a>, <a href="/search/quant-ph?searchtype=author&query=Amer%2C+O">Omar Amer</a>, <a href="/search/quant-ph?searchtype=author&query=Shaydulin%2C+R">Ruslan Shaydulin</a>, <a href="/search/quant-ph?searchtype=author&query=Chakrabarti%2C+S">Shouvanik Chakrabarti</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Guoqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Haowei Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+H">Hao Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Schoch%2C+I">Isidor Schoch</a>, <a href="/search/quant-ph?searchtype=author&query=Kumar%2C+N">Niraj Kumar</a>, <a href="/search/quant-ph?searchtype=author&query=Lim%2C+C">Charles Lim</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Ju Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</a>, <a href="/search/quant-ph?searchtype=author&query=Pistoia%2C+M">Marco Pistoia</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="2310.12893v1-abstract-short" style="display: inline;"> Distributed quantum computing is a promising computational paradigm for performing computations that are beyond the reach of individual quantum devices. Privacy in distributed quantum computing is critical for maintaining confidentiality and protecting the data in the presence of untrusted computing nodes. In this work, we introduce novel blind quantum machine learning protocols based on the quant… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12893v1-abstract-full').style.display = 'inline'; document.getElementById('2310.12893v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.12893v1-abstract-full" style="display: none;"> Distributed quantum computing is a promising computational paradigm for performing computations that are beyond the reach of individual quantum devices. Privacy in distributed quantum computing is critical for maintaining confidentiality and protecting the data in the presence of untrusted computing nodes. In this work, we introduce novel blind quantum machine learning protocols based on the quantum bipartite correlator algorithm. Our protocols have reduced communication overhead while preserving the privacy of data from untrusted parties. We introduce robust algorithm-specific privacy-preserving mechanisms with low computational overhead that do not require complex cryptographic techniques. We then validate the effectiveness of the proposed protocols through complexity and privacy analysis. Our findings pave the way for advancements in distributed quantum computing, opening up new possibilities for privacy-aware machine learning applications in the era of quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12893v1-abstract-full').style.display = 'none'; document.getElementById('2310.12893v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 133, 120602 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.12725">arXiv:2310.12725</a> <span> [<a href="https://arxiv.org/pdf/2310.12725">pdf</a>, <a href="https://arxiv.org/format/2310.12725">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"> Spectrally resolved Franson interference </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jin%2C+R">Rui-Bo Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Z">Zi-Qi Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+D">Dan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chen-Zhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bai-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Shimizu%2C+R">Ryosuke Shimizu</a>, <a href="/search/quant-ph?searchtype=author&query=Takeoka%2C+M">Masahiro Takeoka</a>, <a href="/search/quant-ph?searchtype=author&query=Fujiwara%2C+M">Mikio Fujiwara</a>, <a href="/search/quant-ph?searchtype=author&query=Sasaki%2C+M">Masahide Sasaki</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+P">Pei-Xiang Lu</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="2310.12725v1-abstract-short" style="display: inline;"> Franson interference can be used to test the nonlocal features of energy-time entanglement and has become a standard in quantum physics. However, most of the previous Franson interference experiments were demonstrated in the time domain, and the spectral properties of Franson interference have not been fully explored. Here, we theoretically and experimentally demonstrate spectrally resolved Franso… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12725v1-abstract-full').style.display = 'inline'; document.getElementById('2310.12725v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.12725v1-abstract-full" style="display: none;"> Franson interference can be used to test the nonlocal features of energy-time entanglement and has become a standard in quantum physics. However, most of the previous Franson interference experiments were demonstrated in the time domain, and the spectral properties of Franson interference have not been fully explored. Here, we theoretically and experimentally demonstrate spectrally resolved Franson interference using biphotons with different correlations, including positive correlation, negative correlation, and non-correlation. It is found that the joint spectral intensities of the biphotons can be modulated along both the signal and idler directions, which has potential applications in generating high-dimensional frequency entanglement and time-frequency grid states. This work may provide a new perspective for understanding the spectral-temporal properties of the Franson interferometer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12725v1-abstract-full').style.display = 'none'; document.getElementById('2310.12725v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6+7pages, 3+1 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/2310.08108">arXiv:2310.08108</a> <span> [<a href="https://arxiv.org/pdf/2310.08108">pdf</a>, <a href="https://arxiv.org/ps/2310.08108">ps</a>, <a href="https://arxiv.org/format/2310.08108">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"> Electrical and thermal control of Fabry-P茅rot cavities mediated by Casimir forces </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ge%2C+L">Lixin Ge</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bingzhong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+H">Hao Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+K">Ke Gong</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="2310.08108v1-abstract-short" style="display: inline;"> Dynamic tuning of optical cavities is highly desired in many photonic systems. Here, we show that Fabry-P茅rot(FP) cavities can be actively controlled by the Casimir force. The optical FP cavities consist of a gold nanoplate confronted to an electrical-connecting multi-layer substrate in a liquid environment. The gold nanoplate can be stably suspended due to the balance of repulsive and attractive… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08108v1-abstract-full').style.display = 'inline'; document.getElementById('2310.08108v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.08108v1-abstract-full" style="display: none;"> Dynamic tuning of optical cavities is highly desired in many photonic systems. Here, we show that Fabry-P茅rot(FP) cavities can be actively controlled by the Casimir force. The optical FP cavities consist of a gold nanoplate confronted to an electrical-connecting multi-layer substrate in a liquid environment. The gold nanoplate can be stably suspended due to the balance of repulsive and attractive Casimir forces. Moreover, the suspension distance are modulated strongly by the electric gating or temperature of the system. As a result, we could shift the resonant wavelengthes of the cavities with tens of nanometers at optical frequencies. Finally, we analyze the influence of Brownian motion on the equilibrium distances. Due to the high Q-factor of the FP cavities, our proposed system offers a remarkable platform to experimentally investigate the thermal Casimir effect at sub-micrometer separations <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08108v1-abstract-full').style.display = 'none'; document.getElementById('2310.08108v1-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">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/2308.08821">arXiv:2308.08821</a> <span> [<a href="https://arxiv.org/pdf/2308.08821">pdf</a>, <a href="https://arxiv.org/format/2308.08821">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="Cryptography and Security">cs.CR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/sciadv.adk3258">10.1126/sciadv.adk3258 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental quantum e-commerce </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+X">Xiao-Yu Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Fu%2C+Y">Yao Fu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zeng-Bing 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="2308.08821v2-abstract-short" style="display: inline;"> E-commerce, a type of trading that occurs at a high frequency on the Internet, requires guaranteeing the integrity, authentication and non-repudiation of messages through long distance. As current e-commerce schemes are vulnerable to computational attacks, quantum cryptography, ensuring information-theoretic security against adversary's repudiation and forgery, provides a solution to this problem.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.08821v2-abstract-full').style.display = 'inline'; document.getElementById('2308.08821v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.08821v2-abstract-full" style="display: none;"> E-commerce, a type of trading that occurs at a high frequency on the Internet, requires guaranteeing the integrity, authentication and non-repudiation of messages through long distance. As current e-commerce schemes are vulnerable to computational attacks, quantum cryptography, ensuring information-theoretic security against adversary's repudiation and forgery, provides a solution to this problem. However, quantum solutions generally have much lower performance compared to classical ones. Besides, when considering imperfect devices, the performance of quantum schemes exhibits a significant decline. Here, for the first time, we demonstrate the whole e-commerce process of involving the signing of a contract and payment among three parties by proposing a quantum e-commerce scheme, which shows resistance of attacks from imperfect devices. Results show that with a maximum attenuation of 25 dB among participants, our scheme can achieve a signature rate of 0.82 times per second for an agreement size of approximately 0.428 megabit. This proposed scheme presents a promising solution for providing information-theoretic security for e-commerce. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.08821v2-abstract-full').style.display = 'none'; document.getElementById('2308.08821v2-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 5 figures, 5 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Advances 10, eadk3258 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.10386">arXiv:2307.10386</a> <span> [<a href="https://arxiv.org/pdf/2307.10386">pdf</a>, <a href="https://arxiv.org/format/2307.10386">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 class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41598-023-38572-1">10.1038/s41598-023-38572-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> On the equivalence between squeezing and entanglement potential for two-mode Gaussian states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bohan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Das%2C+A">Aritra Das</a>, <a href="/search/quant-ph?searchtype=author&query=Tserkis%2C+S">Spyros Tserkis</a>, <a href="/search/quant-ph?searchtype=author&query=Narang%2C+P">Prineha Narang</a>, <a href="/search/quant-ph?searchtype=author&query=Lam%2C+P+K">Ping Koy Lam</a>, <a href="/search/quant-ph?searchtype=author&query=Assad%2C+S+M">Syed M. Assad</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="2307.10386v1-abstract-short" style="display: inline;"> The maximum amount of entanglement achievable under passive transformations by continuous-variable states is called the entanglement potential. Recent work has demonstrated that the entanglement potential is upper-bounded by a simple function of the squeezing of formation, and that certain classes of two-mode Gaussian states can indeed saturate this bound, though saturability in the general case r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.10386v1-abstract-full').style.display = 'inline'; document.getElementById('2307.10386v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.10386v1-abstract-full" style="display: none;"> The maximum amount of entanglement achievable under passive transformations by continuous-variable states is called the entanglement potential. Recent work has demonstrated that the entanglement potential is upper-bounded by a simple function of the squeezing of formation, and that certain classes of two-mode Gaussian states can indeed saturate this bound, though saturability in the general case remains an open problem. In this study, we introduce a larger class of states that we prove saturates the bound, and we conjecture that all two-mode Gaussian states can be passively transformed into this class, meaning that for all two-mode Gaussian states, entanglement potential is equivalent to squeezing of formation. We provide an explicit algorithm for the passive transformations and perform extensive numerical testing of our claim, which seeks to unite the resource theories of two characteristic quantum properties of continuous-variable systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.10386v1-abstract-full').style.display = 'none'; document.getElementById('2307.10386v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 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/2307.05305">arXiv:2307.05305</a> <span> [<a href="https://arxiv.org/pdf/2307.05305">pdf</a>, <a href="https://arxiv.org/format/2307.05305">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.108.012414">10.1103/PhysRevA.108.012414 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Visualization of all two-qubit states via partial-transpose-moments </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Lin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+Y">Yi Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+H">Hua Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+Q">Quan Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo 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="2307.05305v1-abstract-short" style="display: inline;"> Efficiently detecting entanglement based on measurable quantities is a basic problem for quantum information processing. Recently, the measurable quantities called partial-transpose (PT)-moments have been proposed to detect and characterize entanglement. In the recently published paper [L. Zhang \emph{et al.}, \href{https://doi.org/10.1002/andp.202200289}{Ann. Phys.(Berlin) \textbf{534}, 2200289 (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.05305v1-abstract-full').style.display = 'inline'; document.getElementById('2307.05305v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.05305v1-abstract-full" style="display: none;"> Efficiently detecting entanglement based on measurable quantities is a basic problem for quantum information processing. Recently, the measurable quantities called partial-transpose (PT)-moments have been proposed to detect and characterize entanglement. In the recently published paper [L. Zhang \emph{et al.}, \href{https://doi.org/10.1002/andp.202200289}{Ann. Phys.(Berlin) \textbf{534}, 2200289 (2022)}], we have already identified the 2-dimensional (2D) region, comprised of the second and third PT-moments, corresponding to two-qubit entangled states, and described the whole region for all two-qubit states. In the present paper, we visualize the 3D region corresponding to all two-qubit states by further involving the fourth PT-moment (the last one for two-qubit states). The characterization of this 3D region can finally be achieved by optimizing some polynomials. Furthermore, we identify the dividing surface which separates the two parts of the whole 3D region corresponding to entangled and separable states respectively. Due to the measurability of PT-moments, we obtain a complete and operational criterion for the detection of two-qubit entanglement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.05305v1-abstract-full').style.display = 'none'; document.getElementById('2307.05305v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">29 pages, LaTeX, 8 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 108, 012414 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.01987">arXiv:2307.01987</a> <span> [<a href="https://arxiv.org/pdf/2307.01987">pdf</a>, <a href="https://arxiv.org/format/2307.01987">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/10.1088/1751-8121/ace409">10.1088/1751-8121/ace409 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tetrahedron genuine entanglement measure of four-qubit systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+M">Meng-Li Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Z">Zhi-Xiang Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Fei%2C+S">Shao-Ming Fei</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="2307.01987v1-abstract-short" style="display: inline;"> Quantifying genuine entanglement is a key task in quantum information theory. We study the quantification of genuine multipartite entanglement for four-qubit systems. Based on the concurrence of nine different classes of four-qubit states, with each class being closed under stochastic local operation and classical communication, we construct a concurrence tetrahedron. Proper genuine four-qubit ent… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01987v1-abstract-full').style.display = 'inline'; document.getElementById('2307.01987v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.01987v1-abstract-full" style="display: none;"> Quantifying genuine entanglement is a key task in quantum information theory. We study the quantification of genuine multipartite entanglement for four-qubit systems. Based on the concurrence of nine different classes of four-qubit states, with each class being closed under stochastic local operation and classical communication, we construct a concurrence tetrahedron. Proper genuine four-qubit entanglement measure is presented by using the volume of the concurrence tetrahedron. For non genuine entangled pure states, the four-qubit entanglement measure classifies the bi-separable entanglement. We show that the concurrence tetrahedron based measure of genuine four-qubit entanglement is not equivalent to the genuine four-partite entanglement concurrence. We illustrate the advantages of the concurrence tetrahedron by detailed examples. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01987v1-abstract-full').style.display = 'none'; document.getElementById('2307.01987v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Phys. A: Math. Theor. 56(2023)315302 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.17428">arXiv:2306.17428</a> <span> [<a href="https://arxiv.org/pdf/2306.17428">pdf</a>, <a href="https://arxiv.org/format/2306.17428">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.19.064083">10.1103/PhysRevApplied.19.064083 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pure-state photon-pair source with a long coherence time for large-scale quantum information processing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</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="2306.17428v1-abstract-short" style="display: inline;"> The Hong-Ou-Mandel interference between independent photons plays a pivotal role in the large-scale quantum networks involving distant nodes. Photons need to work in a pure state for indistinguishability to reach high-quality interference. Also, they need to have a sufficiently long coherence time to reduce the time synchronization requirements in practical application. In this paper, we discuss a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.17428v1-abstract-full').style.display = 'inline'; document.getElementById('2306.17428v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.17428v1-abstract-full" style="display: none;"> The Hong-Ou-Mandel interference between independent photons plays a pivotal role in the large-scale quantum networks involving distant nodes. Photons need to work in a pure state for indistinguishability to reach high-quality interference. Also, they need to have a sufficiently long coherence time to reduce the time synchronization requirements in practical application. In this paper, we discuss a scheme for generating a pure-state photon-pair source with a long coherence time in periodically poled potassium titanyl phosphate (PPKTP) crystals. By selecting the appropriate pump laser and filter, we could simultaneously eliminate the frequency correlation of the parametric photons while achieving a long coherence time. We experimentally developed this pure-state photon-pair source of 780 nm on PPKTP crystals pumped by a 390 nm pulsed laser. The source provided a coherence time of tens of picoseconds, and it showed to have the potential to be applied in long-distance quantum interference. Furthermore, we experimentally demonstrated the Hong-Ou-Mandel (HOM) interference between two photon sources with visibility exceeding the classical limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.17428v1-abstract-full').style.display = 'none'; document.getElementById('2306.17428v1-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 19, 064083 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.11973">arXiv:2306.11973</a> <span> [<a href="https://arxiv.org/pdf/2306.11973">pdf</a>, <a href="https://arxiv.org/format/2306.11973">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/10.1016/j.rinp.2023.106611">10.1016/j.rinp.2023.106611 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Parameterized coherence measure </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+M">Meng-Li Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Z">Zhi-Xiang Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+J">Jin-Min Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Fei%2C+S">Shao-Ming Fei</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="2306.11973v1-abstract-short" style="display: inline;"> Quantifying coherence is an essential endeavor for both quantum mechanical foundations and quantum technologies. We present a bona fide measure of quantum coherence by utilizing the Tsallis relative operator $(伪, 尾)$-entropy. We first prove that the proposed coherence measure fulfills all the criteria of a well defined coherence measure, including the strong monotonicity in the resource theories o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.11973v1-abstract-full').style.display = 'inline'; document.getElementById('2306.11973v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.11973v1-abstract-full" style="display: none;"> Quantifying coherence is an essential endeavor for both quantum mechanical foundations and quantum technologies. We present a bona fide measure of quantum coherence by utilizing the Tsallis relative operator $(伪, 尾)$-entropy. We first prove that the proposed coherence measure fulfills all the criteria of a well defined coherence measure, including the strong monotonicity in the resource theories of quantum coherence. We then study the ordering of the Tsallis relative operator $(伪, 尾)$-entropy of coherence, Tsallis relative $伪$-entropies of coherence, R茅nyi $伪$-entropy of coherence and $l_{1}$ norm of coherence for both pure and mixed qubit states. This provides a new method for defining new coherence measure and entanglement measure, and also provides a new idea for further study of quantum coherence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.11973v1-abstract-full').style.display = 'none'; document.getElementById('2306.11973v1-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Results in Physics,51,106611 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.11105">arXiv:2306.11105</a> <span> [<a href="https://arxiv.org/pdf/2306.11105">pdf</a>, <a href="https://arxiv.org/format/2306.11105">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="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="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.109.L201121">10.1103/PhysRevB.109.L201121 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Non-Bloch dynamics and topology in a classical non-equilibrium process </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">He-Ran Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+F">Fei Song</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhong 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="2306.11105v2-abstract-short" style="display: inline;"> The non-Hermitian skin effect refers to the accumulation of eigenstates near the boundary in open boundary lattice models, which can be systematically characterized using the non-Bloch band theory. Here, we apply the non-Bloch band theory to investigate the stochastic reaction-diffusion process by mapping it to a non-Hermitian Kitaev chain. We exactly obtain the open boundary spectrum and the gene… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.11105v2-abstract-full').style.display = 'inline'; document.getElementById('2306.11105v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.11105v2-abstract-full" style="display: none;"> The non-Hermitian skin effect refers to the accumulation of eigenstates near the boundary in open boundary lattice models, which can be systematically characterized using the non-Bloch band theory. Here, we apply the non-Bloch band theory to investigate the stochastic reaction-diffusion process by mapping it to a non-Hermitian Kitaev chain. We exactly obtain the open boundary spectrum and the generalized Brillouin zone, and identify a robust zero mode arising from the non-Bloch topology. Notably, distinct from its Hermitian counterpart in the quantum context, the zero mode supports anomalous dynamical crossover in the Markov process. We quantitatively demonstrate the intriguing dynamical effects through the spectral decomposition of the Hamiltonian on the non-Bloch eigenstates, and confirm our findings by conducting stochastic simulations with high accuracy. Our study highlights the significant and general role of non-Bloch topology in non-equilibrium dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.11105v2-abstract-full').style.display = 'none'; document.getElementById('2306.11105v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6+13 pages, 3+2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 109, L201121 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.18571">arXiv:2305.18571</a> <span> [<a href="https://arxiv.org/pdf/2305.18571">pdf</a>, <a href="https://arxiv.org/ps/2305.18571">ps</a>, <a href="https://arxiv.org/format/2305.18571">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="Numerical Analysis">math.NA</span> </div> </div> <p class="title is-5 mathjax"> Quantum variational embedding for ground-state energy problems: sum of squares and cluster selection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bowen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+J">Jianfeng Lu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.18571v1-abstract-short" style="display: inline;"> We introduce a sum-of-squares SDP hierarchy approximating the ground-state energy from below for quantum many-body problems, with a natural quantum embedding interpretation. We establish the connections between our approach and other variational methods for lower bounds, including the variational embedding, the RDM method in quantum chemistry, and the Anderson bounds. Additionally, inspired by the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.18571v1-abstract-full').style.display = 'inline'; document.getElementById('2305.18571v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.18571v1-abstract-full" style="display: none;"> We introduce a sum-of-squares SDP hierarchy approximating the ground-state energy from below for quantum many-body problems, with a natural quantum embedding interpretation. We establish the connections between our approach and other variational methods for lower bounds, including the variational embedding, the RDM method in quantum chemistry, and the Anderson bounds. Additionally, inspired by the quantum information theory, we propose efficient strategies for optimizing cluster selection to tighten SDP relaxations while staying within a computational budget. Numerical experiments are presented to demonstrate the effectiveness of our strategy. As a byproduct of our investigation, we find that quantum entanglement has the potential to capture the underlying graph of the many-body Hamiltonian. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.18571v1-abstract-full').style.display = 'none'; document.getElementById('2305.18571v1-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13734">arXiv:2305.13734</a> <span> [<a href="https://arxiv.org/pdf/2305.13734">pdf</a>, <a href="https://arxiv.org/format/2305.13734">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.108.023713">10.1103/PhysRevA.108.023713 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Complete spectral characterization of biphotons by simultaneously determining its frequency sum and difference in a single quantum interferometer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Baihong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+C">Changhua Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+B">Boxin Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Hao%2C+X">Xiangying Hao</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+R">Rui-Bo Jin</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13734v1-abstract-short" style="display: inline;"> We theoretically propose a novel quantum interferometer in which the NOON state interferometer (NOONI) is combined with the Hong-Ou-Mandel interferometer (HOMI). This interferometer combined the advantages of both the NOONI that depends on biphoton frequency sum, and the HOMI that depends on biphoton frequency difference into a single interferometer. It can thus simultaneously obtain the spectral… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13734v1-abstract-full').style.display = 'inline'; document.getElementById('2305.13734v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13734v1-abstract-full" style="display: none;"> We theoretically propose a novel quantum interferometer in which the NOON state interferometer (NOONI) is combined with the Hong-Ou-Mandel interferometer (HOMI). This interferometer combined the advantages of both the NOONI that depends on biphoton frequency sum, and the HOMI that depends on biphoton frequency difference into a single interferometer. It can thus simultaneously obtain the spectral correlation information of biphotons in both frequency sum and difference by taking the Fourier transform from a single time-domain quantum interferogram, which provides a method for complete spectral characterization of an arbitrary two-photon state with exchange symmetry. A direct application of such an interferometer can be found in quantum Fourier-transform spectroscopy where direct spectral measurement is difficult. Furthermore, as it can realize the measurement of time intervals on three scales at the same time, we expect that it can provide a new method in quantum metrology. Finally, we discuss another potential application of such an interferometer in the generation and characterization of high-dimensional and phase-controlled frequency entanglement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13734v1-abstract-full').style.display = 'none'; document.getElementById('2305.13734v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A, 108, 023713 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.06705">arXiv:2305.06705</a> <span> [<a href="https://arxiv.org/pdf/2305.06705">pdf</a>, <a href="https://arxiv.org/format/2305.06705">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/10.1088/1674-1056/acb9f1">10.1088/1674-1056/acb9f1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bounds on positive operator-valued measure based coherence of superposition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+M">Meng-Li Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+J">Jin-Min Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Fei%2C+S">Shao-Ming Fei</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhi-Xi 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="2305.06705v1-abstract-short" style="display: inline;"> Quantum coherence is a fundamental feature of quantum physics and plays a significant role in quantum information processing. By generalizing the resource theory of coherence from von Neumann measurements to positive operator-valued measures (POVMs), POVM-based coherence measures have been proposed with respect to the relative entropy of coherence, the $l_1$ norm of coherence, the robustness of co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06705v1-abstract-full').style.display = 'inline'; document.getElementById('2305.06705v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.06705v1-abstract-full" style="display: none;"> Quantum coherence is a fundamental feature of quantum physics and plays a significant role in quantum information processing. By generalizing the resource theory of coherence from von Neumann measurements to positive operator-valued measures (POVMs), POVM-based coherence measures have been proposed with respect to the relative entropy of coherence, the $l_1$ norm of coherence, the robustness of coherence and the Tsallis relative entropy of coherence. We derive analytically the lower and upper bounds on these POVM-based coherence of an arbitrary given superposed pure state in terms of the POVM-based coherence of the states in superposition. Our results can be used to estimate range of quantum coherence of superposed states. Detailed examples are presented to verify our analytical bounds. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06705v1-abstract-full').style.display = 'none'; document.getElementById('2305.06705v1-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chinese Phys. B 32, 050302 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.06515">arXiv:2305.06515</a> <span> [<a href="https://arxiv.org/pdf/2305.06515">pdf</a>, <a href="https://arxiv.org/ps/2305.06515">ps</a>, <a href="https://arxiv.org/format/2305.06515">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/10.1016/j.rinp.2023.106510">10.1016/j.rinp.2023.106510 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterizing the superposition of arbitrary random quantum states and a known quantum state </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+X">Xiao-Bin Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Fei%2C+S">Shao-Ming Fei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.06515v1-abstract-short" style="display: inline;"> The superposition of states is one of the most fundamental issues in the quantum world. Generally there do not exist physical operations to superpose two unknown random states with nonzero probability. We investigate the superposition problem of unknown qubit states with respect to a known qubit state. It is shown that under trace-nonincreasing completely positive operations the superposable state… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06515v1-abstract-full').style.display = 'inline'; document.getElementById('2305.06515v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.06515v1-abstract-full" style="display: none;"> The superposition of states is one of the most fundamental issues in the quantum world. Generally there do not exist physical operations to superpose two unknown random states with nonzero probability. We investigate the superposition problem of unknown qubit states with respect to a known qubit state. It is shown that under trace-nonincreasing completely positive operations the superposable state sets are located in some circles on the Bloch sphere. Meanwhile, we prove that the quantum states in a circle on the Bloch sphere are superposable with respect to a known state. Finally, for the high-dimensional case, we illustrate that any superposition transformation protocols will violate the no-cloning principle for almost all the states. Our results also promote the understanding and applications of the superposition principle in view of quantum no-go theorems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.06515v1-abstract-full').style.display = 'none'; document.getElementById('2305.06515v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 1 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Results in Physics 49 (2023) 106510 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.01427">arXiv:2303.01427</a> <span> [<a href="https://arxiv.org/pdf/2303.01427">pdf</a>, <a href="https://arxiv.org/format/2303.01427">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-024-00863-4">10.1038/s41534-024-00863-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental error suppression in Cross-Resonance gates via multi-derivative pulse shaping </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Boxi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Calarco%2C+T">Tommaso Calarco</a>, <a href="/search/quant-ph?searchtype=author&query=Motzoi%2C+F">Felix Motzoi</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="2303.01427v4-abstract-short" style="display: inline;"> While quantum circuits are reaching impressive widths in the hundreds of qubits, their depths have not been able to keep pace. In particular, cloud computing gates on multi-qubit, fixed-frequency superconducting chips continue to hover around the 1% error range, contrasting with the progress seen on carefully designed two-qubit chips, where error rates have been pushed towards 0.1%. Despite the st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.01427v4-abstract-full').style.display = 'inline'; document.getElementById('2303.01427v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.01427v4-abstract-full" style="display: none;"> While quantum circuits are reaching impressive widths in the hundreds of qubits, their depths have not been able to keep pace. In particular, cloud computing gates on multi-qubit, fixed-frequency superconducting chips continue to hover around the 1% error range, contrasting with the progress seen on carefully designed two-qubit chips, where error rates have been pushed towards 0.1%. Despite the strong impetus and a plethora of research, experimental demonstration of error suppression on these multi-qubit devices remains challenging, primarily due to the wide distribution of qubit parameters and the demanding calibration process required for advanced control methods. Here, we achieve this goal, using a simple control method based on multi-derivative, multi-constraint pulse shaping, which acts simultaneously against multiple error sources. Our approach establishes a two to fourfold improvement on the default calibration scheme, demonstrated on four qubits on the IBM Quantum Platform with limited and intermittent access, enabling these large-scale fixed-frequency systems to fully take advantage of their superior coherence times. The achieved CNOT fidelities of 99.7(1)% on those publically available qubits come from both coherent control error suppression and accelerated gate time. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.01427v4-abstract-full').style.display = 'none'; document.getElementById('2303.01427v4-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Inf 10, 66 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.13601">arXiv:2302.13601</a> <span> [<a href="https://arxiv.org/pdf/2302.13601">pdf</a>, <a href="https://arxiv.org/ps/2302.13601">ps</a>, <a href="https://arxiv.org/format/2302.13601">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/10.1007/s11128-023-03861-1">10.1007/s11128-023-03861-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> General Monogamy and polygamy properties of quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xie%2C+B">Bing Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+M">Ming-Jing Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo 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="2302.13601v1-abstract-short" style="display: inline;"> Monogamy and Polygamy are important properties of entanglement, which characterize the entanglement distribution of multipartite systems. We study general monogamy and polygamy relations based on the $伪$th $(0\leq伪\leq 纬)$ power of entanglement measures and the $尾$th $(尾\geq 未)$ power of assisted entanglement measures, respectively. We illustrate that these monogamy and polygamy relations are tigh… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.13601v1-abstract-full').style.display = 'inline'; document.getElementById('2302.13601v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.13601v1-abstract-full" style="display: none;"> Monogamy and Polygamy are important properties of entanglement, which characterize the entanglement distribution of multipartite systems. We study general monogamy and polygamy relations based on the $伪$th $(0\leq伪\leq 纬)$ power of entanglement measures and the $尾$th $(尾\geq 未)$ power of assisted entanglement measures, respectively. We illustrate that these monogamy and polygamy relations are tighter than the inequalities in the article [Quantum Inf Process 19, 101], so that the entanglement distribution can be more precisely described for entanglement states that satisfy stronger constraints. For specific entanglement measures such as concurrence and the convex-roof extended negativity, by applying these relations, one can yield the corresponding monogamous and polygamous inequalities, which take the existing ones in the articles [Quantum Inf Process 18, 23] and [Quantum Inf Process 18, 105] as special cases. More details are presented in the examples. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.13601v1-abstract-full').style.display = 'none'; document.getElementById('2302.13601v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages,3 figures, comments are welcome!</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Information Processing (2023) 22:124 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.12743">arXiv:2302.12743</a> <span> [<a href="https://arxiv.org/pdf/2302.12743">pdf</a>, <a href="https://arxiv.org/format/2302.12743">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1002/qute.202300046">10.1002/qute.202300046 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fast wide-field quantum sensor based on solid-state spins integrated with a SPAD array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Guoqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Madonini%2C+F">Francesca Madonini</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Boning Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Changhao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+J">Jinggang Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Villa%2C+F">Federica Villa</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</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="2302.12743v2-abstract-short" style="display: inline;"> Achieving fast, sensitive, and parallel measurement of a large number of quantum particles is an essential task in building large-scale quantum platforms for different quantum information processing applications such as sensing, computation, simulation, and communication. Current quantum platforms in experimental atomic and optical physics based on CMOS sensors and CCD cameras are limited by eithe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.12743v2-abstract-full').style.display = 'inline'; document.getElementById('2302.12743v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.12743v2-abstract-full" style="display: none;"> Achieving fast, sensitive, and parallel measurement of a large number of quantum particles is an essential task in building large-scale quantum platforms for different quantum information processing applications such as sensing, computation, simulation, and communication. Current quantum platforms in experimental atomic and optical physics based on CMOS sensors and CCD cameras are limited by either low sensitivity or slow operational speed. Here we integrate an array of single-photon avalanche diodes with solid-state spin defects in diamond to build a fast wide-field quantum sensor, achieving a frame rate up to 100~kHz. We present the design of the experimental setup to perform spatially resolved imaging of quantum systems. A few exemplary applications, including sensing DC and AC magnetic fields, temperature, strain, local spin density, and charge dynamics, are experimentally demonstrated using an NV ensemble diamond sample. The developed photon detection array is broadly applicable to other platforms such as atom arrays trapped in optical tweezers, optical lattices, donors in silicon, and rare earth ions in solids. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.12743v2-abstract-full').style.display = 'none'; document.getElementById('2302.12743v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Adv Quantum Technol. 2023, 2300046 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.12742">arXiv:2302.12742</a> <span> [<a href="https://arxiv.org/pdf/2302.12742">pdf</a>, <a href="https://arxiv.org/format/2302.12742">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Manipulating solid-state spin concentration through charge transport </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Guoqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Changhao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+H">Hao Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Boning Li</a>, <a href="/search/quant-ph?searchtype=author&query=Madonini%2C+F">Francesca Madonini</a>, <a href="/search/quant-ph?searchtype=author&query=Alsallom%2C+F+F">Faisal F Alsallom</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+W+K+C">Won Kyu Calvin Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+P">Pai Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Villa%2C+F">Federica Villa</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Ju Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</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="2302.12742v2-abstract-short" style="display: inline;"> Solid-state spin defects are attractive candidates for developing quantum sensors and simulators. The spin and charge degrees of freedom in large defect ensembles are a promising platform to explore complex many-body dynamics and the emergence of quantum hydrodynamics. However, many interesting properties can be revealed only upon changes in the density of defects, which instead is usually fixed i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.12742v2-abstract-full').style.display = 'inline'; document.getElementById('2302.12742v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.12742v2-abstract-full" style="display: none;"> Solid-state spin defects are attractive candidates for developing quantum sensors and simulators. The spin and charge degrees of freedom in large defect ensembles are a promising platform to explore complex many-body dynamics and the emergence of quantum hydrodynamics. However, many interesting properties can be revealed only upon changes in the density of defects, which instead is usually fixed in material systems. Increasing the interaction strength by creating denser defect ensembles also brings more decoherence. Ideally one would like to control the spin concentration at will, while keeping fixed decoherence effects. Here we show that by exploiting charge transport, we can take some first steps in this direction, while at the same time characterizing charge transport and its capture by defects. By exploiting the cycling process of ionization and recombination of NV centers in diamonds, we pump electrons from the valence band to the conduction band. These charges are then transported to modulate the spin concentration by changing the charge state of material defects. By developing a wide-field imaging setup integrated with a fast single photon detector array, we achieve a direct and efficient characterization of the charge redistribution process by measuring the complete spectrum of the spin bath with micrometer-scale spatial resolution. We demonstrate the concentration increase of the dominant spin defects by a factor of 2 while keeping the $T_2$ of the NV center, which also provides a potential experimental demonstration of the suppression of spin flip-flops via hyperfine interactions. Our work paves the way to studying many-body dynamics with temporally and spatially tunable interaction strengths in hybrid charge-spin systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.12742v2-abstract-full').style.display = 'none'; document.getElementById('2302.12742v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.05140">arXiv:2302.05140</a> <span> [<a href="https://arxiv.org/pdf/2302.05140">pdf</a>, <a href="https://arxiv.org/ps/2302.05140">ps</a>, <a href="https://arxiv.org/format/2302.05140">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.108.032605">10.1103/PhysRevA.108.032605 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal Single Qubit Tomography: Realization of Locally Optimal Measurements on a Quantum Computer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bacui Li</a>, <a href="/search/quant-ph?searchtype=author&query=Conlon%2C+L+O">Lorcan O. Conlon</a>, <a href="/search/quant-ph?searchtype=author&query=Lam%2C+P+K">Ping Koy Lam</a>, <a href="/search/quant-ph?searchtype=author&query=Assad%2C+S+M">Syed M. Assad</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="2302.05140v2-abstract-short" style="display: inline;"> Quantum bits, or qubits, are the fundamental building blocks of present quantum computers. Hence, it is important to be able to characterize the state of a qubit as accurately as possible. By evaluating the qubit characterization problem from the viewpoint of quantum metrology, we are able to find optimal measurements under the assumption of good prior knowledge. We implement these measurements on… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.05140v2-abstract-full').style.display = 'inline'; document.getElementById('2302.05140v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.05140v2-abstract-full" style="display: none;"> Quantum bits, or qubits, are the fundamental building blocks of present quantum computers. Hence, it is important to be able to characterize the state of a qubit as accurately as possible. By evaluating the qubit characterization problem from the viewpoint of quantum metrology, we are able to find optimal measurements under the assumption of good prior knowledge. We implement these measurements on a superconducting quantum computer. Our experiment produces sufficiently low error to allow the saturation of the theoretical limits, given by the Nagaoka--Hayashi bound. We also present simulations of adaptive measurement schemes utilizing the proposed method. The results of the simulations show the robustness of the method in characterizing arbitrary qubit states with different amounts of prior knowledge. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.05140v2-abstract-full').style.display = 'none'; document.getElementById('2302.05140v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 108, 032605, 2023 </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=Li%2C+B&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Li%2C+B&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Li%2C+B&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Li%2C+B&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Li%2C+B&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a 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