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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Zhang%2C+S&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Zhang%2C+S&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+S&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+S&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+S&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> <li> <a href="/search/?searchtype=author&query=Zhang%2C+S&start=200" class="pagination-link " aria-label="Page 5" aria-current="page">5 </a> </li> <li><span class="pagination-ellipsis">…</span></li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.08110">arXiv:2411.08110</a> <span> [<a href="https://arxiv.org/pdf/2411.08110">pdf</a>, <a href="https://arxiv.org/format/2411.08110">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-ph</span> </div> </div> <p class="title is-5 mathjax"> Characterising memory in quantum channel discrimination via constrained separability problems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ohst%2C+T">Ties-A. Ohst</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Nguyen%2C+H+C">Hai Chau Nguyen</a>, <a href="/search/quant-ph?searchtype=author&query=Pl%C3%A1vala%2C+M">Martin Pl谩vala</a>, <a href="/search/quant-ph?searchtype=author&query=Quintino%2C+M+T">Marco T煤lio Quintino</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="2411.08110v1-abstract-short" style="display: inline;"> Quantum memories are a crucial precondition in many protocols for processing quantum information. A fundamental problem that illustrates this statement is given by the task of channel discrimination, in which an unknown channel drawn from a known random ensemble should be determined by applying it for a single time. In this paper, we characterise the quality of channel discrimination protocols whe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08110v1-abstract-full').style.display = 'inline'; document.getElementById('2411.08110v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.08110v1-abstract-full" style="display: none;"> Quantum memories are a crucial precondition in many protocols for processing quantum information. A fundamental problem that illustrates this statement is given by the task of channel discrimination, in which an unknown channel drawn from a known random ensemble should be determined by applying it for a single time. In this paper, we characterise the quality of channel discrimination protocols when the quantum memory, quantified by the auxiliary dimension, is limited. This is achieved by formulating the problem in terms of separable quantum states with additional affine constraints that all of their factors in each separable decomposition obey. We discuss the computation of upper and lower bounds to the solutions of such problems which allow for new insights into the role of memory in channel discrimination. In addition to the single-copy scenario, this methodological insight allows to systematically characterise quantum and classical memories in adaptive channel discrimination protocols. Especially, our methods enabled us to identify channel discrimination scenarios where classical or quantum memory is required, and to identify the hierarchical and non-hierarchical relationships within adaptive channel discrimination protocols. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.08110v1-abstract-full').style.display = 'none'; document.getElementById('2411.08110v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">32 pages, 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/2411.06648">arXiv:2411.06648</a> <span> [<a href="https://arxiv.org/pdf/2411.06648">pdf</a>, <a href="https://arxiv.org/format/2411.06648">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Driven Critical Dynamics in Measurement-induced Phase Transitions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wantao Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shuo Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jiaqiang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shi-Xin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+S">Shuai Yin</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="2411.06648v1-abstract-short" style="display: inline;"> Measurement-induced phase transitions (MIPT), characterizing abrupt changes in entanglement properties in quantum many-body systems subjected to unitary evolution with interspersed projective measurements, have garnered increasing interest. In this work, we generalize the Kibble-Zurek (KZ) driven critical dynamics that has achieved great success in traditional quantum and classical phase transitio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06648v1-abstract-full').style.display = 'inline'; document.getElementById('2411.06648v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.06648v1-abstract-full" style="display: none;"> Measurement-induced phase transitions (MIPT), characterizing abrupt changes in entanglement properties in quantum many-body systems subjected to unitary evolution with interspersed projective measurements, have garnered increasing interest. In this work, we generalize the Kibble-Zurek (KZ) driven critical dynamics that has achieved great success in traditional quantum and classical phase transitions to MIPT. By linearly changing the measurement probability $p$ to cross the critical point $p_c$ with driving velocity $R$, we identify the dynamic scaling relation of the entanglement entropy $S$ versus $R$ at $p_c$. For decreasing $p$ from the area-law phase, $S$ satisfies $S\propto \ln R$; while for increasing $p$ from the volume-law phase, $S$ satisfies $S\propto R^{1/r}$ in which $r=z+1/谓$ with $z$ and $谓$ being the dynamic and correlation length exponents, respectively. Moreover, we find that the driven dynamics from the volume-law phase violates the adiabatic-impulse scenario of the KZ mechanism. In spite of this, a unified finite-time scaling (FTS) form can be developed to describe these scaling behaviors. Besides, the dynamic scaling of the entanglement entropy of an auxiliary qubit $S_Q$ is also investigated to further confirm the universality of the FTS form. By successfully establishing the driven dynamic scaling theory of this newfashioned entanglement transition, we bring a new fundamental perspective into MIPT that can be detected in fast-developing quantum computers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.06648v1-abstract-full').style.display = 'none'; document.getElementById('2411.06648v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6+6 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/2410.23877">arXiv:2410.23877</a> <span> [<a href="https://arxiv.org/pdf/2410.23877">pdf</a>, <a href="https://arxiv.org/ps/2410.23877">ps</a>, <a href="https://arxiv.org/format/2410.23877">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"> Time evolving matrix product operator (TEMPO) method in a non-diagonal basis set based on derivative of the path integral expression </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuocang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+Q">Qiang Shi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.23877v1-abstract-short" style="display: inline;"> The time-evolving matrix product operator (TEMPO) method is a powerful tool for simulating open system quantum dynamics. Typically, it is used in problems with diagonal system-bath coupling, where analytical expressions for discretized influence functional are available. In this work, we aim to address issues related to off-diagonal coupling by extending the TEMPO algorithm to accommodate arbitrar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23877v1-abstract-full').style.display = 'inline'; document.getElementById('2410.23877v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.23877v1-abstract-full" style="display: none;"> The time-evolving matrix product operator (TEMPO) method is a powerful tool for simulating open system quantum dynamics. Typically, it is used in problems with diagonal system-bath coupling, where analytical expressions for discretized influence functional are available. In this work, we aim to address issues related to off-diagonal coupling by extending the TEMPO algorithm to accommodate arbitrary basis sets. The proposed approach is based on computing the derivative of the discretized path integral expression of a generalized influence functional when increasing one time step, which yields an equation of motion valid for non-diagonal basis set and arbitrary number of non-commuting baths. The generalized influence functional is then obtained by integrating the resulting differential equation. Applicability of the the new method is then tested by simulating one- and two- qubit systems coupled to both Z- and X-type baths. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23877v1-abstract-full').style.display = 'none'; document.getElementById('2410.23877v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.21386">arXiv:2410.21386</a> <span> [<a href="https://arxiv.org/pdf/2410.21386">pdf</a>, <a href="https://arxiv.org/format/2410.21386">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="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Supersymmetry dynamics on Rydberg atom arrays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shuo Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Z">Zhengzhi Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shi-Xin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+H">Hong Yao</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="2410.21386v1-abstract-short" style="display: inline;"> Spacetime supersymmetry (SUSY) that interchanges fermions and bosons is of great theoretical importance but has not yet been revealed experimentally in particle physics. It has also been desired to explore quantum-mechanical SUSY in microscopic lattice models. Inspired by the recent experiments of Floquet engineering of Rydberg atom arrays, we find that quantum mechanical SUSY can be realized in F… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.21386v1-abstract-full').style.display = 'inline'; document.getElementById('2410.21386v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.21386v1-abstract-full" style="display: none;"> Spacetime supersymmetry (SUSY) that interchanges fermions and bosons is of great theoretical importance but has not yet been revealed experimentally in particle physics. It has also been desired to explore quantum-mechanical SUSY in microscopic lattice models. Inspired by the recent experiments of Floquet engineering of Rydberg atom arrays, we find that quantum mechanical SUSY can be realized in Floquet Rydberg atom arrays. Moreover, we utilize the supercharge dynamics to demonstrate the SUSY property of the model under investigation: the expectation value of supercharge freezes under time evolution for supersymmetric lattice models in contrast to the trivial oscillation for generic nonsupersymmetric lattice models. The proposal is validated on direct simulation of Rydberg atom arrays' dynamics and ready for experiments. This work sheds light on the future experimental exploration of SUSY with the help of Rydberg atom arrays. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.21386v1-abstract-full').style.display = 'none'; document.getElementById('2410.21386v1-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">Comments:</span> <span class="has-text-grey-dark mathjax">4 pages, 3 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.20090">arXiv:2410.20090</a> <span> [<a href="https://arxiv.org/pdf/2410.20090">pdf</a>, <a href="https://arxiv.org/format/2410.20090">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="Adaptation and Self-Organizing Systems">nlin.AO</span> </div> </div> <p class="title is-5 mathjax"> Nonlinear spin dynamics induced by feedback under continuous Larmor frequency distributions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+T">Tishuo Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Z">Zhihuang Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shizhong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Z">Zhenhua Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.20090v1-abstract-short" style="display: inline;"> Nonlinear spin dynamics are essential in exploring nonequilibrium quantum phenomena and have broad applications in precision measurement. Among these systems, the combination of a bias magnetic field and feedback mechanisms can induce self-sustained oscillations at the base Larmor frequency due to nonlinearity. These features have driven the development of single-species and multiple-species spin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20090v1-abstract-full').style.display = 'inline'; document.getElementById('2410.20090v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.20090v1-abstract-full" style="display: none;"> Nonlinear spin dynamics are essential in exploring nonequilibrium quantum phenomena and have broad applications in precision measurement. Among these systems, the combination of a bias magnetic field and feedback mechanisms can induce self-sustained oscillations at the base Larmor frequency due to nonlinearity. These features have driven the development of single-species and multiple-species spin masers. The latter, with multiple discrete Larmor frequencies, provides significant advantages for precision measurement by mitigating uncertainties in precession frequencies due to long-term drifts in experimental conditions. The self-sustained oscillations of single-species and multiple-species spin masers correspond to limit cycles and quasi-periodic orbits of the stable nonlinear dynamics of the systems respectively; the correspondence is elucidated in a recent study on a related spin system featuring two discrete intrinsic Larmor frequencies under dual bias magnetic fields. Here, we extend the study to the case that the intrinsic Larmor frequencies of individual spins of the system, given rise to by an inhomogeneous bias magnetic field, form a continuum. We show that generically the stable dynamics of the system includes limit cycles, quasi-periodic orbits, and chaos. We establish the relation between the synchronization frequency of limit cycles and the field inhomogeneity and derive an equation determining the stability of limit cycles. Furthermore, detailed characteristics of different dynamical phases, especially the robustness of limit cycles and quasi-periodic orbits against experimental fluctuations, are discussed. Our findings not only encompass the case of discrete Larmor frequencies, but also provide crucial insights for precision measurement and the exploration of continuous time crystals and quasi-crystals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20090v1-abstract-full').style.display = 'none'; document.getElementById('2410.20090v1-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 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/2410.18847">arXiv:2410.18847</a> <span> [<a href="https://arxiv.org/pdf/2410.18847">pdf</a>, <a href="https://arxiv.org/format/2410.18847">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> A novel quantum machine learning classifier to search for new physics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yang%2C+J">Ji-Chong Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuai Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yue%2C+C">Chong-Xing Yue</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="2410.18847v1-abstract-short" style="display: inline;"> Due to the success of the Standard Model~(SM), it is reasonable to anticipate that, the signal of new physics~(NP) beyond the SM is small, and future searches for NP and precision tests of the SM will require high luminosity collider experiments. Moreover, as the precision tests of the SM advances, rarer processes with a greater number of final-state particles will require consideration, which wil… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.18847v1-abstract-full').style.display = 'inline'; document.getElementById('2410.18847v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.18847v1-abstract-full" style="display: none;"> Due to the success of the Standard Model~(SM), it is reasonable to anticipate that, the signal of new physics~(NP) beyond the SM is small, and future searches for NP and precision tests of the SM will require high luminosity collider experiments. Moreover, as the precision tests of the SM advances, rarer processes with a greater number of final-state particles will require consideration, which will in turn require the analysis of a multitude of observables. As an inherent consequence of the high luminosity, the generation of a large amount of experimental data in a large feature space presents a significant challenge for data processing. In recent years, quantum machine learning has emerged as a promising approach for processing large amounts of complex data on a quantum computer. In this study, we propose a variational quantum searching neighbor~(VQSN) algorithm to search for NP. As an example, we apply the VQSN in the phenomenological study of the gluon quartic gauge couplings~(gQGCs) at the Large Hadron Collider. The results suggest that VQSN demonstrates superior efficiency to a classical counterpart k-nearest neighbor algorithm, even when dealing with classical data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.18847v1-abstract-full').style.display = 'none'; document.getElementById('2410.18847v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 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">18 pages, 1 figure</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/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/2410.15455">arXiv:2410.15455</a> <span> [<a href="https://arxiv.org/pdf/2410.15455">pdf</a>, <a href="https://arxiv.org/format/2410.15455">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of quantum information collapse-and-revival in a strongly-interacting Rydberg atom array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+D">De-Sheng Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yao-Wen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hao-Xiang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+P">Peng Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+D">Dong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+K">Kuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shun-Yao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+B">Biao Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+L">Lu Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yitong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Lin Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.15455v1-abstract-short" style="display: inline;"> Interactions of isolated quantum many-body systems typically scramble local information into the entire system and make it unrecoverable. Ergodicity-breaking systems possess the potential to exhibit fundamentally different information scrambling dynamics beyond this paradigm. For many-body localized systems with strong ergodicity breaking, local transport vanishes and information scrambles logarit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15455v1-abstract-full').style.display = 'inline'; document.getElementById('2410.15455v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.15455v1-abstract-full" style="display: none;"> Interactions of isolated quantum many-body systems typically scramble local information into the entire system and make it unrecoverable. Ergodicity-breaking systems possess the potential to exhibit fundamentally different information scrambling dynamics beyond this paradigm. For many-body localized systems with strong ergodicity breaking, local transport vanishes and information scrambles logarithmically slowly. Whereas in Rydberg atom arrays, local qubit flips induce dynamical retardation on surrounding qubits through the Rydberg blockade effect, giving rise to quantum many-body scars that weakly break ergodicity, and resulting in the predicted unconventional quantum information spreading behaviours. Here, we present the first measurements of out-of-time-ordered correlators and Holevo information in a Rydberg atom array, enabling us to precisely track quantum information scrambling and transport dynamics. By leveraging these tools, we observe a novel spatio-temporal collapse-and-revival behaviour of quantum information, which differs from both typical chaotic and many-body localized systems. Our experiment sheds light on the unique information dynamics in many-body systems with kinetic constraints, and demonstrates an effective digital-analogue approach to coherently reverse time evolution and steer information propagation in near-term quantum devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.15455v1-abstract-full').style.display = 'none'; document.getElementById('2410.15455v1-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">12 pages, 6 figures + Supplementary Information 37 pages, 24 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/2410.04409">arXiv:2410.04409</a> <span> [<a href="https://arxiv.org/pdf/2410.04409">pdf</a>, <a href="https://arxiv.org/format/2410.04409">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="Data Structures and Algorithms">cs.DS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optimization and Control">math.OC</span> </div> </div> <p class="title is-5 mathjax"> Quantum Approximate Optimization Algorithms for Maxmimum Cut on Low-Girth Graphs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+T">Tongyang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+Y">Yuexin Su</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Z">Ziyi Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shengyu 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="2410.04409v1-abstract-short" style="display: inline;"> Maximum cut (MaxCut) on graphs is a classic NP-hard problem. In quantum computing, Farhi, Gutmann, and Goldstone proposed the Quantum Approximate Optimization Algorithm (QAOA) for solving the MaxCut problem. Its guarantee on cut fraction (the fraction of edges in the output cut over all edges) was mainly studied for high-girth graphs, i.e., graphs with only long cycles. On the other hand, low-girt… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04409v1-abstract-full').style.display = 'inline'; document.getElementById('2410.04409v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.04409v1-abstract-full" style="display: none;"> Maximum cut (MaxCut) on graphs is a classic NP-hard problem. In quantum computing, Farhi, Gutmann, and Goldstone proposed the Quantum Approximate Optimization Algorithm (QAOA) for solving the MaxCut problem. Its guarantee on cut fraction (the fraction of edges in the output cut over all edges) was mainly studied for high-girth graphs, i.e., graphs with only long cycles. On the other hand, low-girth graphs are ubiquitous in theoretical computer science, including expander graphs being outstanding examples with wide applications in theory and beyond. In this paper, we apply QAOA to MaxCut on a set of expander graphs proposed by Mohanty and O'Donnell known as additive product graphs. Additionally, we apply multi-angle QAOA (ma-QAOA) to better utilize the graph structure of additive product graphs in ansatz design. In theory, we derive an iterative formula to calculate the expected cut fraction of such graphs. On the other hand, we conduct numerical experiments to compare between best-known classical local algorithms and QAOA with constant depth. Our results demonstrate that QAOA outperforms the best-known classical algorithms by 0.3% to 5.2% on several additive product graphs, while ma-QAOA further enhances this advantage by an additional 0.6% to 2.5%. In particular, we observe cases that ma-QAOA exhibits superiority over best-known classical algorithms but QAOA does not. Furthermore, we extend our experiments to planar graphs such as tiling grid graphs, where QAOA also demonstrates an advantage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04409v1-abstract-full').style.display = 'none'; document.getElementById('2410.04409v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 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">20pages, 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/2410.02547">arXiv:2410.02547</a> <span> [<a href="https://arxiv.org/pdf/2410.02547">pdf</a>, <a href="https://arxiv.org/format/2410.02547">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> </div> </div> <p class="title is-5 mathjax"> Personalized Quantum Federated Learning for Privacy Image Classification </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shi%2C+J">Jinjing Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Tian Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shichao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xuelong Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.02547v1-abstract-short" style="display: inline;"> Quantum federated learning has brought about the improvement of privacy image classification, while the lack of personality of the client model may contribute to the suboptimal of quantum federated learning. A personalized quantum federated learning algorithm for privacy image classification is proposed to enhance the personality of the client model in the case of an imbalanced distribution of ima… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.02547v1-abstract-full').style.display = 'inline'; document.getElementById('2410.02547v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.02547v1-abstract-full" style="display: none;"> Quantum federated learning has brought about the improvement of privacy image classification, while the lack of personality of the client model may contribute to the suboptimal of quantum federated learning. A personalized quantum federated learning algorithm for privacy image classification is proposed to enhance the personality of the client model in the case of an imbalanced distribution of images. First, a personalized quantum federated learning model is constructed, in which a personalized layer is set for the client model to maintain the personalized parameters. Second, a personalized quantum federated learning algorithm is introduced to secure the information exchanged between the client and server.Third, the personalized federated learning is applied to image classification on the FashionMNIST dataset, and the experimental results indicate that the personalized quantum federated learning algorithm can obtain global and local models with excellent performance, even in situations where local training samples are imbalanced. The server's accuracy is 100% with 8 clients and a distribution parameter of 100, outperforming the non-personalized model by 7%. The average client accuracy is 2.9% higher than that of the non-personalized model with 2 clients and a distribution parameter of 1. Compared to previous quantum federated learning algorithms, the proposed personalized quantum federated learning algorithm eliminates the need for additional local training while safeguarding both model and data privacy.It may facilitate broader adoption and application of quantum technologies, and pave the way for more secure, scalable, and efficient quantum distribute machine learning solutions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.02547v1-abstract-full').style.display = 'none'; document.getElementById('2410.02547v1-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 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/2409.06547">arXiv:2409.06547</a> <span> [<a href="https://arxiv.org/pdf/2409.06547">pdf</a>, <a href="https://arxiv.org/format/2409.06547">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="Statistical Mechanics">cond-mat.stat-mech</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"> Imaginary-time Mpemba effect in quantum many-body systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chang%2C+W">Wei-Xuan Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+S">Shuai Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shi-Xin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zi-Xiang 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="2409.06547v1-abstract-short" style="display: inline;"> Various exotic phenomena emerge in non-equilibrium quantum many-body systems. The Mpemba effect, denoting the situation where a hot system freezes faster than the colder one, is a counterintuitive non-equilibrium phenomenon that has attracted enduring interest for more than half a century. In this Letter, we report a novel phenomenon of the Mpemba effect in the imaginary-time relaxation dynamics i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.06547v1-abstract-full').style.display = 'inline'; document.getElementById('2409.06547v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.06547v1-abstract-full" style="display: none;"> Various exotic phenomena emerge in non-equilibrium quantum many-body systems. The Mpemba effect, denoting the situation where a hot system freezes faster than the colder one, is a counterintuitive non-equilibrium phenomenon that has attracted enduring interest for more than half a century. In this Letter, we report a novel phenomenon of the Mpemba effect in the imaginary-time relaxation dynamics in quantum many-body systems, dubbed as imaginary-time Mpemba effect (ITME). Through numerically exact quantum Monte-Carlo (QMC) simulation, we unambiguously demonstrate that in different classes of interacting quantum models, the initial states with higher energy are relaxed faster than lower-energy initial states in the process of imaginary-time relaxation. The emergence of ITME is intimately associated with the low-energy excitations in quantum many-body systems. More crucially, since imaginary-time dynamics is broadly applied in numerical simulation on the quantum many-body ground states, the discovery of ITME potentially provides a new pathway to expedite the quantum many-body computation, particularly for QMC involving the sign problem. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.06547v1-abstract-full').style.display = 'none'; document.getElementById('2409.06547v1-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 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">4.5+8 pages, 4+6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.05431">arXiv:2409.05431</a> <span> [<a href="https://arxiv.org/pdf/2409.05431">pdf</a>, <a href="https://arxiv.org/format/2409.05431">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"> Noise Suppression via Coherent Quantum Feedback: a Schr{枚}dinger Picture Approach </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shikun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+G">Guofeng 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="2409.05431v1-abstract-short" style="display: inline;"> In this article, we explore the possibility of achieving noise suppression for finite-dimensional quantum systems through coherent feedback. For a quantum plant which is expected to evolve according to a target trajectory, noise effect potentially deforms the plant state trajectory from the desired one. It is then hoped that a coherent feedback protocol can be designed that counteracts noise. In t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05431v1-abstract-full').style.display = 'inline'; document.getElementById('2409.05431v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.05431v1-abstract-full" style="display: none;"> In this article, we explore the possibility of achieving noise suppression for finite-dimensional quantum systems through coherent feedback. For a quantum plant which is expected to evolve according to a target trajectory, noise effect potentially deforms the plant state trajectory from the desired one. It is then hoped that a coherent feedback protocol can be designed that counteracts noise. In terms of coping with transient noise, we present several conditions on coherent feedback protocols under which noise-affected trajectories can be driven back towards desired ones asymptotically. As for rejecting persistent noise, conditions on protocols are given which ensure that the error between the target and feedback-corrected trajectories in the long-time limit can be effectively suppressed. Moreover, a possible construction of coherent feedback protocols which satisfies the given conditions is provided. Our theoretical results are illustrated by an example which involves a two-qubit plant and a two-level controller. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05431v1-abstract-full').style.display = 'none'; document.getElementById('2409.05431v1-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">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">14 pages, 2 figures. Accepted for publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.01601">arXiv:2409.01601</a> <span> [<a href="https://arxiv.org/pdf/2409.01601">pdf</a>, <a href="https://arxiv.org/format/2409.01601">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"> Single nuclear spin detection and control in a van der Waals material </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gao%2C+X">Xingyu Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Vaidya%2C+S">Sumukh Vaidya</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+K">Kejun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Dikshit%2C+S">Saakshi Dikshit</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shimin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ju%2C+P">Peng Ju</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+K">Kunhong Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Y">Yuanbin Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Ping%2C+Y">Yuan Ping</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+T">Tongcang 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="2409.01601v1-abstract-short" style="display: inline;"> Optically active spin defects in solids are leading candidates for quantum sensing and quantum networking. Recently, single spin defects were discovered in hexagonal boron nitride (hBN), a layered van der Waals (vdW) material. Due to its two-dimensional structure, hBN allows spin defects to be positioned closer to target samples than in three-dimensional crystals, making it ideal for atomic-scale… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.01601v1-abstract-full').style.display = 'inline'; document.getElementById('2409.01601v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.01601v1-abstract-full" style="display: none;"> Optically active spin defects in solids are leading candidates for quantum sensing and quantum networking. Recently, single spin defects were discovered in hexagonal boron nitride (hBN), a layered van der Waals (vdW) material. Due to its two-dimensional structure, hBN allows spin defects to be positioned closer to target samples than in three-dimensional crystals, making it ideal for atomic-scale quantum sensing, including nuclear magnetic resonance (NMR) of single molecules. However, the chemical structures of these defects remain unknown, and detecting a single nuclear spin with an hBN spin defect has been elusive. In this study, we created single spin defects in hBN using $^{13}$C ion implantation and identified three distinct defect types. We observed both $S=1$ and $S=1/2$ spin states within a single hBN spin defect, with only the $S=1/2$ states showing strong hyperfine interactions with nearby $^{13}$C nuclear spins. For the first time, we demonstrated atomic-scale NMR and coherent control of individual nuclear spins in a vdW material. By comparing experimental results with density-functional theory calculations, we propose chemical structures for these spin defects. Our work advances the understanding of single spin defects in hBN and provides a pathway to enhance quantum sensing using hBN spin defects with nuclear spins as quantum memories. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.01601v1-abstract-full').style.display = 'none'; document.getElementById('2409.01601v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 September, 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">9 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/2408.13015">arXiv:2408.13015</a> <span> [<a href="https://arxiv.org/pdf/2408.13015">pdf</a>, <a href="https://arxiv.org/format/2408.13015">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-dimentional Multipartite Entanglement Structure Detection with Low Cost </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+R">Rui Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shikun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+Z">Zheng Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+C">Chunxiao Du</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+Z">Zhisong Xiao</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="2408.13015v1-abstract-short" style="display: inline;"> Quantum entanglement detection and characterization are crucial for various quantum information processes. Most existing methods for entanglement detection rely heavily on a complete description of the quantum state, which requires numerous measurements and complex setups. This makes these theoretically sound approaches costly and impractical, as the system size increases. In this work, we propose… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13015v1-abstract-full').style.display = 'inline'; document.getElementById('2408.13015v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.13015v1-abstract-full" style="display: none;"> Quantum entanglement detection and characterization are crucial for various quantum information processes. Most existing methods for entanglement detection rely heavily on a complete description of the quantum state, which requires numerous measurements and complex setups. This makes these theoretically sound approaches costly and impractical, as the system size increases. In this work, we propose a multi-view neural network model to generate representations suitable for entanglement structure detection. The number of required quantum measurements is polynomial rather than exponential increase with the qubit number. This remarkable reduction in resource costs makes it possible to detect specific entanglement structures in large-scale systems. Numerical simulations show that our method achieves over 95% detection accuracy for up to 19 qubits systems. By enabling a universal, flexible and resource-efficient analysis of entanglement structures, our approach enhances the capability of utilizing quantum states across a wide range of applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13015v1-abstract-full').style.display = 'none'; document.getElementById('2408.13015v1-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 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/2408.09783">arXiv:2408.09783</a> <span> [<a href="https://arxiv.org/pdf/2408.09783">pdf</a>, <a href="https://arxiv.org/format/2408.09783">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 metrological capability as a probe for quantum phase transition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangbei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chu%2C+Y">Yaoming Chu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shaoliang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+J">Jianming Cai</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="2408.09783v3-abstract-short" style="display: inline;"> The comprehension of quantum phase transitions (QPTs) is considered as a critical foothold in the field of many-body physics. Developing protocols to effectively identify and understand QPTs thus represents a key but challenging task for present quantum simulation experiments. Here, we establish a dynamical quench-interferometric framework to probe a zero-temperature QPT, which utilizes the evolve… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09783v3-abstract-full').style.display = 'inline'; document.getElementById('2408.09783v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.09783v3-abstract-full" style="display: none;"> The comprehension of quantum phase transitions (QPTs) is considered as a critical foothold in the field of many-body physics. Developing protocols to effectively identify and understand QPTs thus represents a key but challenging task for present quantum simulation experiments. Here, we establish a dynamical quench-interferometric framework to probe a zero-temperature QPT, which utilizes the evolved state by quenching the QPT Hamiltonian as input of a unitary interferometer. The metrological capability quantified by the quantum Fisher information captivatingly shows an unique peak in the vicinity of the quantum critical point, allowing us to probe the QPT without cooling the system to its ground state. We show that the probing can be implemented by extracting quantum fluctuations of the interferometric generator as well as parameter estimation uncertainty of the interferometric phase, and subsequently allows identifying the boundary of the phase diagram. Our results establish an important link between QPTs and quantum metrology, and enrich the toolbox of studying non-equilibrium many-body physics in current quantum simulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09783v3-abstract-full').style.display = 'none'; document.getElementById('2408.09783v3-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">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/2408.07750">arXiv:2408.07750</a> <span> [<a href="https://arxiv.org/pdf/2408.07750">pdf</a>, <a href="https://arxiv.org/format/2408.07750">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum Mpemba effects in many-body localization systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shuo Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Hao-Kai Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+S">Shuai Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shi-Xin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+H">Hong Yao</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="2408.07750v1-abstract-short" style="display: inline;"> The nonequilibrium dynamics of quantum many-body systems have attracted growing attention due to various intriguing phenomena absent in equilibrium physics. One famous example is the quantum Mpemba effect, where the subsystem symmetry is restored faster under a symmetric quench from a more asymmetric initial state. The quantum Mpemba effect has been extensively studied in integrable and chaotic sy… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.07750v1-abstract-full').style.display = 'inline'; document.getElementById('2408.07750v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.07750v1-abstract-full" style="display: none;"> The nonequilibrium dynamics of quantum many-body systems have attracted growing attention due to various intriguing phenomena absent in equilibrium physics. One famous example is the quantum Mpemba effect, where the subsystem symmetry is restored faster under a symmetric quench from a more asymmetric initial state. The quantum Mpemba effect has been extensively studied in integrable and chaotic systems. In this Letter, we investigate symmetry restoration and quantum Mpemba effect in many-body localized systems with various initial states. We reveal that the symmetry can still be fully restored in many-body localization phases without approaching thermal equilibrium. Furthermore, we demonstrate that the presence of the quantum Mpemba effect is universal for any initial tilted product state, contrasting to the cases in the chaotic systems where the presence of the quantum Mpemba effect relies on the choice of initial states. We also provide a theoretical analysis of symmetry restoration and quantum Mpemba effects with the help of the effective model for many-body localization. This Letter not only sheds light on extending the quantum Mpemba effect to more non-equilibrium settings but also contributes to a deeper understanding of the many-body localization. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.07750v1-abstract-full').style.display = 'none'; document.getElementById('2408.07750v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages (including supplemental materials), 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.05943">arXiv:2408.05943</a> <span> [<a href="https://arxiv.org/pdf/2408.05943">pdf</a>, <a href="https://arxiv.org/format/2408.05943">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"> Closed-Loop Designed Open-Loop Control of Quantum Systems: An Error Analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shikun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+G">Guofeng 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="2408.05943v1-abstract-short" style="display: inline;"> Quantum Lyapunov control, an important class of quantum control methods, aims at generating converging dynamics guided by Lyapunov-based theoretical tools. However, unlike the case of classical systems, disturbance caused by quantum measurement hinders direct and exact realization of the theoretical feedback dynamics designed with Lyapunov theory. Regarding this issue, the idea of closed-loop desi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.05943v1-abstract-full').style.display = 'inline'; document.getElementById('2408.05943v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.05943v1-abstract-full" style="display: none;"> Quantum Lyapunov control, an important class of quantum control methods, aims at generating converging dynamics guided by Lyapunov-based theoretical tools. However, unlike the case of classical systems, disturbance caused by quantum measurement hinders direct and exact realization of the theoretical feedback dynamics designed with Lyapunov theory. Regarding this issue, the idea of closed-loop designed open-loop control has been mentioned in literature, which means to design the closed-loop dynamics theoretically, simulate the closed-loop system, generate control pulses based on simulation and apply them to the real plant in an open-loop fashion. Based on bilinear quantum control model, we analyze in this article the error, i.e., difference between the theoretical and real systems' time-evolved states, incurred by the procedures of closed-loop designed open-loop control. It is proved that the error at an arbitrary time converges to a unitary transformation of initialization error as the number of simulation grids between 0 and that time tends to infinity. Moreover, it is found that once the simulation accuracy reaches a certain level, adopting more accurate (thus possibly more expensive) numerical simulation methods does not efficiently improve convergence. We also present an upper bound on the error norm and an example to illustrate our results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.05943v1-abstract-full').style.display = 'none'; document.getElementById('2408.05943v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.01980">arXiv:2408.01980</a> <span> [<a href="https://arxiv.org/pdf/2408.01980">pdf</a>, <a href="https://arxiv.org/format/2408.01980">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Measurement Induced Magic Resources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Gongchu Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Si-Qi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+X">Xu-Song Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Huaqing Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yuancheng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">You Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+G">Geng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hamma%2C+A">Alioscia Hamma</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.01980v3-abstract-short" style="display: inline;"> Magic states and magic gates are crucial for achieving universal computation, but some important questions about how magic resources should be implemented to attain quantum advantage have remained unexplored, for instance, in the context of Measurement-based Quantum Computation (MQC) with only single-qubit measurements. This work bridges the gap between MQC and the resource theory of magic by intr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.01980v3-abstract-full').style.display = 'inline'; document.getElementById('2408.01980v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.01980v3-abstract-full" style="display: none;"> Magic states and magic gates are crucial for achieving universal computation, but some important questions about how magic resources should be implemented to attain quantum advantage have remained unexplored, for instance, in the context of Measurement-based Quantum Computation (MQC) with only single-qubit measurements. This work bridges the gap between MQC and the resource theory of magic by introducing the concept of ``invested'' and ``potential" magic resources. The former quantifies the magic cost associated with the MQC framework, serving both as a witness of magic resources and an upper bound for the realization of a desired unitary transformation. Potential magic resources represent the maximum achievable magic resource in a given graph structure defining the MQC. We utilize these concepts to analyze the magic resource requirements of the Quantum Fourier Transform (QFT) and provide a fresh perspective on the universality of MQC of different resource states, highlighting the crucial role of non-Pauli measurements for injecting magic. We demonstrate experimentally our theoretical predictions in a high-fidelity four-photon setup and demonstrate the efficiency of MQC in generating magic states, surpassing the limitations of conventional magic state injection methods. Our findings pave the way for future research exploring magic resource optimization and novel distillation schemes within the MQC framework, contributing to the advancement of fault-tolerant universal quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.01980v3-abstract-full').style.display = 'none'; document.getElementById('2408.01980v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.12587">arXiv:2407.12587</a> <span> [<a href="https://arxiv.org/pdf/2407.12587">pdf</a>, <a href="https://arxiv.org/ps/2407.12587">ps</a>, <a href="https://arxiv.org/format/2407.12587">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> On the dynamical Lie algebras of quantum approximate optimization algorithms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Allcock%2C+J">Jonathan Allcock</a>, <a href="/search/quant-ph?searchtype=author&query=Santha%2C+M">Miklos Santha</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+P">Pei Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shengyu 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="2407.12587v1-abstract-short" style="display: inline;"> Dynamical Lie algebras (DLAs) have emerged as a valuable tool in the study of parameterized quantum circuits, helping to characterize both their expressiveness and trainability. In particular, the absence or presence of barren plateaus (BPs) -- flat regions in parameter space that prevent the efficient training of variational quantum algorithms -- has recently been shown to be intimately related t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.12587v1-abstract-full').style.display = 'inline'; document.getElementById('2407.12587v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.12587v1-abstract-full" style="display: none;"> Dynamical Lie algebras (DLAs) have emerged as a valuable tool in the study of parameterized quantum circuits, helping to characterize both their expressiveness and trainability. In particular, the absence or presence of barren plateaus (BPs) -- flat regions in parameter space that prevent the efficient training of variational quantum algorithms -- has recently been shown to be intimately related to quantities derived from the associated DLA. In this work, we investigate DLAs for the quantum approximate optimization algorithm (QAOA), one of the most studied variational quantum algorithms for solving graph MaxCut and other combinatorial optimization problems. While DLAs for QAOA circuits have been studied before, existing results have either been based on numerical evidence, or else correspond to DLA generators specifically chosen to be universal for quantum computation on a subspace of states. We initiate an analytical study of barren plateaus and other statistics of QAOA algorithms, and give bounds on the dimensions of the corresponding DLAs and their centers for general graphs. We then focus on the $n$-vertex cycle and complete graphs. For the cycle graph we give an explicit basis, identify its decomposition into the direct sum of a $2$-dimensional center and a semisimple component isomorphic to $n-1$ copies of $su(2)$. We give an explicit basis for this isomorphism, and a closed-form expression for the variance of the cost function, proving the absence of BPs. For the complete graph we prove that the dimension of the DLA is $O(n^3)$ and give an explicit basis for the DLA. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.12587v1-abstract-full').style.display = 'none'; document.getElementById('2407.12587v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 July, 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/2407.11744">arXiv:2407.11744</a> <span> [<a href="https://arxiv.org/pdf/2407.11744">pdf</a>, <a href="https://arxiv.org/format/2407.11744">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"> Improved Quantum Power Method and Numerical Integration Using Quantum Singular Value Transformation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Nghiem%2C+N+A">Nhat A. Nghiem</a>, <a href="/search/quant-ph?searchtype=author&query=Sukeno%2C+H">Hiroki Sukeno</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuyu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+T">Tzu-Chieh 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="2407.11744v1-abstract-short" style="display: inline;"> Quantum singular value transformation (QSVT) is a framework that has been shown to unify many primitives in quantum algorithms. In this work, we leverage the QSVT framework in two directions. We first show that the QSVT framework can accelerate one recently introduced quantum power method, which substantially improves its running time. Additionally, we incorporate several elementary numerical inte… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11744v1-abstract-full').style.display = 'inline'; document.getElementById('2407.11744v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11744v1-abstract-full" style="display: none;"> Quantum singular value transformation (QSVT) is a framework that has been shown to unify many primitives in quantum algorithms. In this work, we leverage the QSVT framework in two directions. We first show that the QSVT framework can accelerate one recently introduced quantum power method, which substantially improves its running time. Additionally, we incorporate several elementary numerical integration techniques, such as the rectangular method, Monte Carlo method, and quadrature method, into the QSVT framework, which results in polynomial speedup with respect to the size or the number of points of the grid. Our results thus provide further examples to demonstrate the potential of the QSVT and how it may enhance quantum algorithmic tasks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11744v1-abstract-full').style.display = 'none'; document.getElementById('2407.11744v1-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 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/2407.07697">arXiv:2407.07697</a> <span> [<a href="https://arxiv.org/pdf/2407.07697">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Revealing spontaneous symmetry breaking in continuous time crystals </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Y">Yuanjiang Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">Chenyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bei Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+J">Jin Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+C">Chao Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yaohua Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+X">Xian Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Cuicui Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yong-Chun Liu</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="2407.07697v1-abstract-short" style="display: inline;"> Spontaneous symmetry breaking plays a pivotal role in physics ranging from the emergence of elementary particles to the phase transitions of matter. The spontaneous breaking of continuous time translation symmetry leads to a novel state of matter named continuous time crystal (CTC). It exhibits periodic oscillation without the need for periodic driving, and the relative phases for repetitively rea… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07697v1-abstract-full').style.display = 'inline'; document.getElementById('2407.07697v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.07697v1-abstract-full" style="display: none;"> Spontaneous symmetry breaking plays a pivotal role in physics ranging from the emergence of elementary particles to the phase transitions of matter. The spontaneous breaking of continuous time translation symmetry leads to a novel state of matter named continuous time crystal (CTC). It exhibits periodic oscillation without the need for periodic driving, and the relative phases for repetitively realized oscillations are random. However, the mechanism behind the spontaneous symmetry breaking in CTCs, particularly the random phases, remains elusive. Here we propose and experimentally realize two types of CTCs based on distinct mechanisms: manifold topology and near-chaotic motion. We observe both types of CTCs in thermal atomic ensembles by artificially synthesizing spin-spin nonlinear interactions through a measurement-feedback scheme. Our work provides general recipes for the realization of CTCs, and paves the way for exploring CTCs in various systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07697v1-abstract-full').style.display = 'none'; document.getElementById('2407.07697v1-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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.06687">arXiv:2407.06687</a> <span> [<a href="https://arxiv.org/pdf/2407.06687">pdf</a>, <a href="https://arxiv.org/format/2407.06687">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Realization of Conditional Operations through Transition Pathway Engineering </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Sheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+P">Peng Duan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yun-Jie Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+T">Tian-Le Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Peng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+R">Ren-Ze Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiao-Yan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Ze-An Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+L">Liang-Liang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yong Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Hai-Feng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+L">Lei Du</a>, <a href="/search/quant-ph?searchtype=author&query=Tao%2C+H">Hao-Ran Tao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zhi-Fei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yuan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+Z">Zhi-Long Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Kong%2C+W">Wei-Cheng Kong</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zhao-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yu-Chun Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guo-Ping Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.06687v2-abstract-short" style="display: inline;"> In the NISQ era, achieving large-scale quantum computing demands compact circuits to mitigate decoherence and gate error accumulation. Quantum operations with diverse degrees of freedom hold promise for circuit compression, but conventional approaches encounter challenges in simultaneously adjusting multiple parameters. Here, we propose a transition composite gate (TCG) scheme grounded on state-se… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06687v2-abstract-full').style.display = 'inline'; document.getElementById('2407.06687v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.06687v2-abstract-full" style="display: none;"> In the NISQ era, achieving large-scale quantum computing demands compact circuits to mitigate decoherence and gate error accumulation. Quantum operations with diverse degrees of freedom hold promise for circuit compression, but conventional approaches encounter challenges in simultaneously adjusting multiple parameters. Here, we propose a transition composite gate (TCG) scheme grounded on state-selective transition path engineering, enabling more expressive conditional operations. We experimentally validate a controlled unitary (CU) gate as an example, with independent and continuous parameters. By adjusting the parameters of $\rm X^{12}$ gate, we obtain the CU family with a fidelity range of 95.2% to 99.0% leveraging quantum process tomography (QPT). To demonstrate the capability of circuit compression, we use TCG scheme to prepare 3-qubit Greenberger-Horne-Zeilinger (GHZ) and W states, with the fidelity of 96.77% and 95.72%. TCG can achieve the reduction in circuit depth of about 40% and 44% compared with the use of CZ gates only. Moreover, we show that short-path TCG (SPTCG) can further reduce the state-preparation circuit time cost. The TCG scheme exhibits advantages in certain quantum circuits and shows significant potential for large-scale quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.06687v2-abstract-full').style.display = 'none'; document.getElementById('2407.06687v2-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">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">21 pages, 12 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.04901">arXiv:2407.04901</a> <span> [<a href="https://arxiv.org/pdf/2407.04901">pdf</a>, <a href="https://arxiv.org/format/2407.04901">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Three-Body Recombination of Ultracold Microwave-Shielded Polar Molecules </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Stevenson%2C+I">Ian Stevenson</a>, <a href="/search/quant-ph?searchtype=author&query=Singh%2C+S">Shayamal Singh</a>, <a href="/search/quant-ph?searchtype=author&query=Elkamshishy%2C+A">Ahmed Elkamshishy</a>, <a href="/search/quant-ph?searchtype=author&query=Bigagli%2C+N">Niccol贸 Bigagli</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+W">Weijun Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Siwei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Greene%2C+C+H">Chris H. Greene</a>, <a href="/search/quant-ph?searchtype=author&query=Will%2C+S">Sebastian Will</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="2407.04901v1-abstract-short" style="display: inline;"> A combined experimental and theoretical study is carried out on the three-body recombination process in a gas of microwave-shielded polar molecules. For ground-state polar molecules dressed with a strong microwave field, field-linked bound states can appear in the intermolecular potential. We model three-body recombination into such bound states using classical trajectory calculations. Our results… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.04901v1-abstract-full').style.display = 'inline'; document.getElementById('2407.04901v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.04901v1-abstract-full" style="display: none;"> A combined experimental and theoretical study is carried out on the three-body recombination process in a gas of microwave-shielded polar molecules. For ground-state polar molecules dressed with a strong microwave field, field-linked bound states can appear in the intermolecular potential. We model three-body recombination into such bound states using classical trajectory calculations. Our results show that recombination can explain the enhanced loss rates observed at small microwave detunings in trapped samples of bosonic NaCs [Bigagli, $\textit{et al.}$, Nat. Phys. $\textbf{19}$ 1579-1584 (2023)]. Specifically, our calculations reproduce the experimentally measured three-body loss rates across a wide range of microwave Rabi couplings, detunings, and temperatures. This work suggests that for bosonic shielded molecular systems in which the two-body loss is sufficiently suppressed and a field-linked bound state is present, the dominant loss process will be three-body recombination. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.04901v1-abstract-full').style.display = 'none'; document.getElementById('2407.04901v1-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> <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, 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/2407.02787">arXiv:2407.02787</a> <span> [<a href="https://arxiv.org/pdf/2407.02787">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> A versatile quantum microwave photonic signal processing platform based on coincidence window selection technique </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinghua Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yifan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+X">Xiao Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Quan%2C+R">Runai Quan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+M">Mingtao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang 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="2407.02787v1-abstract-short" style="display: inline;"> Quantum microwave photonics (QMWP) is an innovative approach that combines energy-time entangled biphoton sources as the optical carrier with time-correlated single-photon detection for high-speed RF signal recovery. This groundbreaking method offers unique advantages such as nonlocal RF signal encoding and robust resistance to dispersion-induced frequency fading. This paper explores the versatili… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02787v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02787v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02787v1-abstract-full" style="display: none;"> Quantum microwave photonics (QMWP) is an innovative approach that combines energy-time entangled biphoton sources as the optical carrier with time-correlated single-photon detection for high-speed RF signal recovery. This groundbreaking method offers unique advantages such as nonlocal RF signal encoding and robust resistance to dispersion-induced frequency fading. This paper explores the versatility of processing the quantum microwave photonic signal by utilizing coincidence window selection on the biphoton coincidence distribution. The demonstration includes finely-tunable RF phase shifting, flexible multi-tap transversal filtering (with up to 15 taps), and photonically implemented RF mixing, leveraging the nonlocal RF mapping characteristic of QMWP. These accomplishments significantly enhance the capability of microwave photonic systems in processing ultra-weak signals, opening up new possibilities for various applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02787v1-abstract-full').style.display = 'none'; document.getElementById('2407.02787v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 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/2407.02774">arXiv:2407.02774</a> <span> [<a href="https://arxiv.org/pdf/2407.02774">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum microwave photonic mixer with a large spurious-free dynamic range </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinghua Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yifan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+X">Xiao Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Quan%2C+R">Runai Quan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+M">Mingtao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang 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="2407.02774v1-abstract-short" style="display: inline;"> As one of the most fundamental functionalities of microwave photonics, microwave frequency mixing plays an essential role in modern radars and wireless communication systems. However, the commonly utilized intensity modulation in the systems often leads to inadequate spurious-free dynamic range (SFDR) for many sought-after applications. Quantum microwave photonics technique offers a promising solu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02774v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02774v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02774v1-abstract-full" style="display: none;"> As one of the most fundamental functionalities of microwave photonics, microwave frequency mixing plays an essential role in modern radars and wireless communication systems. However, the commonly utilized intensity modulation in the systems often leads to inadequate spurious-free dynamic range (SFDR) for many sought-after applications. Quantum microwave photonics technique offers a promising solution for improving SFDR in terms of higher-order harmonic distortion. In this paper, we demonstrate two types of quantum microwave photonic mixers based on the configuration of the intensity modulators: cascade-type and parallel-type. Leveraging the nonlocal RF signal encoding capability, both types of quantum microwave photonic mixers not only exhibit the advantage of dual-channel output but also present significant improvement in SFDR. Specifically, the parallel-type quantum microwave photonic mixer achieves a remarkable SFDR value of 113.6 dB.Hz1/2, which is 30 dB better than that of the cascade-type quantum microwave photonic mixer. When compared to the classical microwave photonic mixer, this enhancement reaches a notable 53.6 dB at the expense of 8 dB conversion loss. These results highlight the superiority of quantum microwave photonic mixers in the fields of microwave and millimeter-wave systems. Further applying multi-photon frequency entangled sources as optical carriers, the dual-channel microwave frequency conversion capability endowed by the quantum microwave photonic mixer can be extended to enhance the performance of multiple-paths microwave mixing which is essential for radar net systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02774v1-abstract-full').style.display = 'none'; document.getElementById('2407.02774v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 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/2406.19308">arXiv:2406.19308</a> <span> [<a href="https://arxiv.org/pdf/2406.19308">pdf</a>, <a href="https://arxiv.org/format/2406.19308">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dressed-State Spectroscopy and Magic Trapping of Microwave-Shielded NaCs Molecules </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Siwei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+W">Weijun Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Bigagli%2C+N">Niccol貌 Bigagli</a>, <a href="/search/quant-ph?searchtype=author&query=Warner%2C+C">Claire Warner</a>, <a href="/search/quant-ph?searchtype=author&query=Stevenson%2C+I">Ian Stevenson</a>, <a href="/search/quant-ph?searchtype=author&query=Will%2C+S">Sebastian Will</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="2406.19308v1-abstract-short" style="display: inline;"> We report on the optical polarizability of microwave-shielded ultracold NaCs molecules in an optical dipole trap. While dressing a pair of rotational states with a microwave field, we observe a marked dependence of the optical polarizability on the intensity and detuning of the dressing field. To precisely characterize differential energy shifts between dressed rotational states, we establish dres… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19308v1-abstract-full').style.display = 'inline'; document.getElementById('2406.19308v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.19308v1-abstract-full" style="display: none;"> We report on the optical polarizability of microwave-shielded ultracold NaCs molecules in an optical dipole trap. While dressing a pair of rotational states with a microwave field, we observe a marked dependence of the optical polarizability on the intensity and detuning of the dressing field. To precisely characterize differential energy shifts between dressed rotational states, we establish dressed-state spectroscopy. For strong dressing fields, we find that a magic rotational transition can be engineered and demonstrate its insensitivity to laser intensity fluctuations. The results of this work have direct relevance for evaporative cooling and the recent demonstration of molecular Bose-Einstein condensates [Bigagli, et al., Nature (2024)] and may open a door to precision microwave spectroscopy in interacting many-body systems of microwave-shielded molecules. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19308v1-abstract-full').style.display = 'none'; document.getElementById('2406.19308v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">5 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/2406.19212">arXiv:2406.19212</a> <span> [<a href="https://arxiv.org/pdf/2406.19212">pdf</a>, <a href="https://arxiv.org/format/2406.19212">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"> JuliVQC: an Efficient Variational Quantum Circuit Simulator for Near-Term Quantum Algorithms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liao%2C+W">Wei-You Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xiao-Yue Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+C">Chen Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+H">He-Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+C">Chu Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.19212v1-abstract-short" style="display: inline;"> We introduce JuliVQC: a light-weight, yet extremely efficient variational quantum circuit simulator. JuliVQC is part of an effort for classical simulation of the \textit{Zuchongzhi} quantum processors, where it is extensively used to characterize the circuit noises, as a building block in the Schr$\ddot{\text{o}}$dinger-Feynman algorithm for classical verification and performance benchmarking, and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19212v1-abstract-full').style.display = 'inline'; document.getElementById('2406.19212v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.19212v1-abstract-full" style="display: none;"> We introduce JuliVQC: a light-weight, yet extremely efficient variational quantum circuit simulator. JuliVQC is part of an effort for classical simulation of the \textit{Zuchongzhi} quantum processors, where it is extensively used to characterize the circuit noises, as a building block in the Schr$\ddot{\text{o}}$dinger-Feynman algorithm for classical verification and performance benchmarking, and for variational optimization of the Fsim gate parameters. The design principle of JuliVQC is three-fold: (1) Transparent implementation of its core algorithms, realized by using the high-performance script language Julia; (2) Efficiency is the focus, with a cache-friendly implementation of each elementary operations and support for shared-memory parallelization; (3) Native support of automatic differentiation for both the noiseless and noisy quantum circuits. We perform extensive numerical experiments on JuliVQC in different application scenarios, including quantum circuits, variational quantum circuits and their noisy counterparts, which show that its performance is among the top of the popular alternatives. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19212v1-abstract-full').style.display = 'none'; document.getElementById('2406.19212v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">12 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/2406.11788">arXiv:2406.11788</a> <span> [<a href="https://arxiv.org/pdf/2406.11788">pdf</a>, <a href="https://arxiv.org/format/2406.11788">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Holographic Classical Shadow Tomography </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuhan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xiaozhou Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ippoliti%2C+M">Matteo Ippoliti</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+Y">Yi-Zhuang You</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="2406.11788v1-abstract-short" style="display: inline;"> We introduce "holographic shadows", a new class of randomized measurement schemes for classical shadow tomography that achieves the optimal scaling of sample complexity for learning geometrically local Pauli operators at any length scale, without the need for fine-tuning protocol parameters such as circuit depth or measurement rate. Our approach utilizes hierarchical quantum circuits, such as tree… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.11788v1-abstract-full').style.display = 'inline'; document.getElementById('2406.11788v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.11788v1-abstract-full" style="display: none;"> We introduce "holographic shadows", a new class of randomized measurement schemes for classical shadow tomography that achieves the optimal scaling of sample complexity for learning geometrically local Pauli operators at any length scale, without the need for fine-tuning protocol parameters such as circuit depth or measurement rate. Our approach utilizes hierarchical quantum circuits, such as tree quantum circuits or holographic random tensor networks. Measurements within the holographic bulk correspond to measurements at different scales on the boundary (i.e. the physical system of interests), facilitating efficient quantum state estimation across observable at all scales. Considering the task of estimating string-like Pauli observables supported on contiguous intervals of $k$ sites in a 1D system, our method achieves an optimal sample complexity scaling of $\sim d^k\mathrm{poly}(k)$, with $d$ the local Hilbert space dimension. We present a holographic minimal cut framework to demonstrate the universality of this sample complexity scaling and validate it with numerical simulations, illustrating the efficacy of holographic shadows in enhancing quantum state learning capabilities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.11788v1-abstract-full').style.display = 'none'; document.getElementById('2406.11788v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 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">Comments:</span> <span class="has-text-grey-dark mathjax">20 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/2406.07625">arXiv:2406.07625</a> <span> [<a href="https://arxiv.org/pdf/2406.07625">pdf</a>, <a href="https://arxiv.org/format/2406.07625">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="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 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/s41567-024-02664-0">10.1038/s41567-024-02664-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Emergent Universal Quench Dynamics in Randomly Interacting Spin Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuchen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+T">Tian-Gang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Z">Ze Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+P">Pai Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shengyu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Fu%2C+R">Riqiang Fu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Ren Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+W">Wei Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+P">Pengfei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhai%2C+H">Hui Zhai</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+X">Xinhua Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+J">Jiangfeng Du</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="2406.07625v1-abstract-short" style="display: inline;"> Universality often emerges in low-energy equilibrium physics of quantum many-body systems, despite their microscopic complexity and variety. Recently, there has been a growing interest in studying far-from-equilibrium dynamics of quantum many-body systems. Such dynamics usually involves highly excited states beyond the traditional low-energy theory description. Whether universal behaviors can also… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07625v1-abstract-full').style.display = 'inline'; document.getElementById('2406.07625v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.07625v1-abstract-full" style="display: none;"> Universality often emerges in low-energy equilibrium physics of quantum many-body systems, despite their microscopic complexity and variety. Recently, there has been a growing interest in studying far-from-equilibrium dynamics of quantum many-body systems. Such dynamics usually involves highly excited states beyond the traditional low-energy theory description. Whether universal behaviors can also emerge in such non-equilibrium dynamics is a central issue at the frontier of quantum dynamics. Here we report the experimental observation of universal dynamics by monitoring the spin depolarization process in a solid-state NMR system described by an ensemble of randomly interacting spins. The spin depolarization can be related to temporal spin-spin correlation functions at high temperatures. We discover a remarkable phenomenon that these correlation functions obey a universal functional form. This experimental fact helps us identify the dominant interacting processes in the spin depolarization dynamics that lead to this universality. Our observation demonstrates the existence of universality even in non-equilibrium dynamics at high temperatures, thereby complementing the well-established universality in low-energy physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07625v1-abstract-full').style.display = 'none'; document.getElementById('2406.07625v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 4 figures; Supplementary Information 26 pages, 11 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Phys. (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.07225">arXiv:2406.07225</a> <span> [<a href="https://arxiv.org/pdf/2406.07225">pdf</a>, <a href="https://arxiv.org/format/2406.07225">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 generic and robust quantum agent inspired by deep meta-reinforcement learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Miao%2C+Z">Zibo Miao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shihui Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+Y">Yu Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Tao%2C+S">Sibo Tao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.07225v1-abstract-short" style="display: inline;"> Deep reinforcement learning (deep RL) has enabled human- or superhuman- performances in various applications. Recently, deep RL has also been adopted to improve the performance of quantum control. However, a large volume of data is typically required to train the neural network in deep RL, making it inefficient compared with the traditional optimal quantum control method. Here, we thus develop a n… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07225v1-abstract-full').style.display = 'inline'; document.getElementById('2406.07225v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.07225v1-abstract-full" style="display: none;"> Deep reinforcement learning (deep RL) has enabled human- or superhuman- performances in various applications. Recently, deep RL has also been adopted to improve the performance of quantum control. However, a large volume of data is typically required to train the neural network in deep RL, making it inefficient compared with the traditional optimal quantum control method. Here, we thus develop a new training algorithm inspired by the deep meta-reinforcement learning (deep meta-RL), which requires significantly less training data. The trained neural network is adaptive and robust. In addition, the algorithm proposed by us has been applied to design the Hadamard gate and show that for a wide range of parameters the infidelity of the obtained gate can be made of the order 0.0001. Our algorithm can also automatically adjust the number of pulses required to generate the target gate, which is different from the traditional optimal quantum control method which typically fixes the number of pulses a-priory. The results of this paper can pave the way towards constructing a universally robust quantum agent catering to the different demands in quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.07225v1-abstract-full').style.display = 'none'; document.getElementById('2406.07225v1-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 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/2406.06063">arXiv:2406.06063</a> <span> [<a href="https://arxiv.org/pdf/2406.06063">pdf</a>, <a href="https://arxiv.org/format/2406.06063">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Enabling Large-Scale and High-Precision Fluid Simulations on Near-Term Quantum Computers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zhao-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+T">Teng-Yang Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+C">Chuang-Chao Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+L">Liang Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+M">Ming-Yang Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhuang%2C+X">Xi-Ning Zhuang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xiao-Fan Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yun-Jie Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+T">Tai-Ping Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yong Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+L">Lei Du</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+L">Liang-Liang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Hai-Feng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Tao%2C+H">Hao-Ran Tao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+T">Tian-Le Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiao-Yan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Ze-An Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+P">Peng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Sheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+R">Ren-Ze Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+Z">Zhi-Long Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Kong%2C+W">Wei-Cheng Kong</a>, <a href="/search/quant-ph?searchtype=author&query=Dou%2C+M">Meng-Han Dou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jun-Chao Wang</a> , et al. (7 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.06063v3-abstract-short" style="display: inline;"> Quantum computational fluid dynamics (QCFD) offers a promising alternative to classical computational fluid dynamics (CFD) by leveraging quantum algorithms for higher efficiency. This paper introduces a comprehensive QCFD method, including an iterative method "Iterative-QLS" that suppresses error in quantum linear solver, and a subspace method to scale the solution to a larger size. We implement o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.06063v3-abstract-full').style.display = 'inline'; document.getElementById('2406.06063v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.06063v3-abstract-full" style="display: none;"> Quantum computational fluid dynamics (QCFD) offers a promising alternative to classical computational fluid dynamics (CFD) by leveraging quantum algorithms for higher efficiency. This paper introduces a comprehensive QCFD method, including an iterative method "Iterative-QLS" that suppresses error in quantum linear solver, and a subspace method to scale the solution to a larger size. We implement our method on a superconducting quantum computer, demonstrating successful simulations of steady Poiseuille flow and unsteady acoustic wave propagation. The Poiseuille flow simulation achieved a relative error of less than $0.2\%$, and the unsteady acoustic wave simulation solved a 5043-dimensional matrix. We emphasize the utilization of the quantum-classical hybrid approach in applications of near-term quantum computers. By adapting to quantum hardware constraints and offering scalable solutions for large-scale CFD problems, our method paves the way for practical applications of near-term quantum computers in computational science. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.06063v3-abstract-full').style.display = 'none'; document.getElementById('2406.06063v3-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 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">Comments:</span> <span class="has-text-grey-dark mathjax">31 pages, 10 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/2406.01997">arXiv:2406.01997</a> <span> [<a href="https://arxiv.org/pdf/2406.01997">pdf</a>, <a href="https://arxiv.org/format/2406.01997">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Machine-Learning Insights on Entanglement-trainability Correlation of Parameterized Quantum Circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shikun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+Z">Zheng Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+R">Rui Li</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+C">Chunxiao Du</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+Z">Zhisong Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yongyou 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="2406.01997v2-abstract-short" style="display: inline;"> Variational quantum algorithms (VQAs) have emerged as the leading strategy to obtain quantum advantage on the current noisy intermediate-scale devices. However, their entanglement-trainability correlation, as the major reason for the barren plateau (BP) phenomenon, poses a challenge to their applications. In this Letter, we suggest a gate-to-tensor (GTT) encoding method for parameterized quantum c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01997v2-abstract-full').style.display = 'inline'; document.getElementById('2406.01997v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.01997v2-abstract-full" style="display: none;"> Variational quantum algorithms (VQAs) have emerged as the leading strategy to obtain quantum advantage on the current noisy intermediate-scale devices. However, their entanglement-trainability correlation, as the major reason for the barren plateau (BP) phenomenon, poses a challenge to their applications. In this Letter, we suggest a gate-to-tensor (GTT) encoding method for parameterized quantum circuits (PQCs), with which two long short-term memory networks (L-G networks) are trained to predict both entanglement and trainability. The remarkable capabilities of the L-G networks afford a statistical way to delve into the entanglement-trainability correlation of PQCs within a dataset encompassing millions of instances. This machine-learning-driven method first confirms that the more entanglement, the more possible the BP problem. Then, we observe that there still exist PQCs with both high entanglement and high trainability. Furthermore, the trained L-G networks result in an impressive increase in time efficiency by about one million times when constructing a PQC with specific entanglement and trainability, demonstrating their practical applications in VQAs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01997v2-abstract-full').style.display = 'none'; document.getElementById('2406.01997v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 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/2406.01715">arXiv:2406.01715</a> <span> [<a href="https://arxiv.org/pdf/2406.01715">pdf</a>, <a href="https://arxiv.org/format/2406.01715">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="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Ferromagnetic semimetal and charge-density wave phases of interacting electrons in a honeycomb moir茅 potential </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yubo Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Morales%2C+M+A">Miguel A. Morales</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shiwei 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="2406.01715v1-abstract-short" style="display: inline;"> The exploration of quantum phases in moir茅 systems has drawn intense experimental and theoretical efforts. The realization of honeycomb symmetry has been a recent focus. The combination of strong interaction and honeycomb symmetry can lead to exotic electronic states such as fractional Chern insulator, unconventional superconductor, and quantum spin liquid. Accurate computations in such systems, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01715v1-abstract-full').style.display = 'inline'; document.getElementById('2406.01715v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.01715v1-abstract-full" style="display: none;"> The exploration of quantum phases in moir茅 systems has drawn intense experimental and theoretical efforts. The realization of honeycomb symmetry has been a recent focus. The combination of strong interaction and honeycomb symmetry can lead to exotic electronic states such as fractional Chern insulator, unconventional superconductor, and quantum spin liquid. Accurate computations in such systems, with reliable treatment of strong long-ranged Coulomb interaction and approaching the large system sizes to extract thermodynamic phases, are mostly missing. We study the two-dimensional electron gas on a honeycomb moir茅 lattice at quarter filling, using fixed-phase diffusion Monte Carlo. The ground state phases of this important model are determined in the parameter regime relevant to current experiments. With increasing moir茅 potential, the systems transitions from a paramagnetic metal to an itinerant ferromagnetic semimetal and then a charge-density-wave insulator. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01715v1-abstract-full').style.display = 'none'; document.getElementById('2406.01715v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.20696">arXiv:2405.20696</a> <span> [<a href="https://arxiv.org/pdf/2405.20696">pdf</a>, <a href="https://arxiv.org/format/2405.20696">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"> Directly Estimating Mixed-State Entanglement with Bell Measurement Assistance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Gong-Chu Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Si-Qi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+X">Xu-Song Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">You Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+G">Geng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.20696v2-abstract-short" style="display: inline;"> Entanglement plays a fundamental role in quantum physics and information processing. Here, we develop an unbiased estimator for mixed-state entanglement in the few-shot scenario and directly estimate it using random unitary evolution in a photonic system. As a supplement to traditional projective measurements, we incorporate Bell measurements on qubit-pairs, enriching the previous randomized measu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.20696v2-abstract-full').style.display = 'inline'; document.getElementById('2405.20696v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.20696v2-abstract-full" style="display: none;"> Entanglement plays a fundamental role in quantum physics and information processing. Here, we develop an unbiased estimator for mixed-state entanglement in the few-shot scenario and directly estimate it using random unitary evolution in a photonic system. As a supplement to traditional projective measurements, we incorporate Bell measurements on qubit-pairs, enriching the previous randomized measurement scheme, which is no-go in this task with only local unitary evolution. The scheme is scalable to n-qubits via Bell measurements on qubit-pairs. The estimator can be derived directly from a few consecutive outcomes while exhibiting greater robustness to system errors and noise compared to schemes based on shadow estimation. We find that, under a fixed measurement resource, the way with more versatile measurement settings with fewer repeats per setting is more efficient. Our protocol and demonstration advance the direct characterization of quantum states in practice. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.20696v2-abstract-full').style.display = 'none'; document.getElementById('2405.20696v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 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">5 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/2405.19397">arXiv:2405.19397</a> <span> [<a href="https://arxiv.org/pdf/2405.19397">pdf</a>, <a href="https://arxiv.org/format/2405.19397">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="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Ground state phases of the two-dimension electron gas with a unified variational approach </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Smith%2C+C">Conor Smith</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yixiao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Levy%2C+R">Ryan Levy</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yubo Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Morales%2C+M+A">Miguel A. Morales</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shiwei 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="2405.19397v1-abstract-short" style="display: inline;"> The two-dimensional electron gas (2DEG) is a fundamental model, which is drawing increasing interest because of recent advances in experimental and theoretical studies of 2D materials. Current understanding of the ground state of the 2DEG relies on quantum Monte Carlo calculations, based on variational comparisons of different ansatze for different phases. We use a single variational ansatz, a gen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.19397v1-abstract-full').style.display = 'inline'; document.getElementById('2405.19397v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.19397v1-abstract-full" style="display: none;"> The two-dimensional electron gas (2DEG) is a fundamental model, which is drawing increasing interest because of recent advances in experimental and theoretical studies of 2D materials. Current understanding of the ground state of the 2DEG relies on quantum Monte Carlo calculations, based on variational comparisons of different ansatze for different phases. We use a single variational ansatz, a general backflow-type wave function using a message-passing neural quantum state architecture, for a unified description across the entire density range. The variational optimization consistently leads to lower ground-state energies than previous best results. Transition into a Wigner crystal (WC) phase occurs automatically at rs = 37 +/- 1, a density lower than currently believed. Between the liquid and WC phases, the same ansatz and variational search strongly suggest the existence of intermediate states in a broad range of densities, with enhanced short-range nematic spin correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.19397v1-abstract-full').style.display = 'none'; document.getElementById('2405.19397v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.13935">arXiv:2405.13935</a> <span> [<a href="https://arxiv.org/pdf/2405.13935">pdf</a>, <a href="https://arxiv.org/format/2405.13935">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="Other Condensed Matter">cond-mat.other</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"> Out-of-plane magnetic phase diagram of Kitaev quantum spin liquid candidate Na2Co2TeO6 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shengzhi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+S">Sangyun Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Brosha%2C+E">Eric Brosha</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Q">Qing Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Haidong Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Zapf%2C+V+S">Vivien S. Zapf</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+M">Minseong 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="2405.13935v3-abstract-short" style="display: inline;"> We have investigated the magnetic properties and mapped out the phase diagram of the honeycomb magnet Na2Co2TeO6 with Co 3d7 in out-of-plane magnetic fields. This material has previously been proposed to show nearest-neighbor Kitaev interactions between Co spins and maybe even Kitaev quantum spin liquid behavior in high fields. At low magnetic fields, we observe a thermal phase transition at TN =… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.13935v3-abstract-full').style.display = 'inline'; document.getElementById('2405.13935v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.13935v3-abstract-full" style="display: none;"> We have investigated the magnetic properties and mapped out the phase diagram of the honeycomb magnet Na2Co2TeO6 with Co 3d7 in out-of-plane magnetic fields. This material has previously been proposed to show nearest-neighbor Kitaev interactions between Co spins and maybe even Kitaev quantum spin liquid behavior in high fields. At low magnetic fields, we observe a thermal phase transition at TN = 27 K, transitioning from a paramagnetic state to a canonical ferrimagnetic state. Under the application of magnetic fields, a spin flop-like phase transition occurred before saturation of J = 1/2 between 10 K and TN. Below 10 K, a peak-dip-peak structure emerges between 10 and 17 T in the magnetic susceptibility (dM/dH) before the magnetic saturation, reminiscent of magnetic plateau behavior. The measurement of the magnetocaloric effect also shows dip-peak-dip behavior in this field range. Our data can be explained by an XXZ model with a single ion anisotropy and possibly small Kitaev and 螕 exchange interactions. We also unambiguously determined the magnetization saturation field that helps constrain the energy scale of the exchange interactions <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.13935v3-abstract-full').style.display = 'none'; document.getElementById('2405.13935v3-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">v1</span> submitted 22 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">LA-UR-24-24990</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.13369">arXiv:2405.13369</a> <span> [<a href="https://arxiv.org/pdf/2405.13369">pdf</a>, <a href="https://arxiv.org/format/2405.13369">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Realization of a crosstalk-free multi-ion node for long-distance quantum networking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lai%2C+P+-">P. -C. Lai</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Y. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+J+-">J. -X. Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+Z+-">Z. -B. Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z+-">Z. -Q. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">S. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+P+-">P. -Y. Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Tian%2C+Z+-">Z. -C. Tian</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Y+-">Y. -D. Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Chang%2C+X+-">X. -Y. Chang</a>, <a href="/search/quant-ph?searchtype=author&query=Qi%2C+B+-">B. -X. Qi</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y+-">Y. -Y. Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z+-">Z. -C. Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y+-">Y. -K. Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Y. Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pu%2C+Y+-">Y. -F. Pu</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="2405.13369v1-abstract-short" style="display: inline;"> Trapped atomic ions constitute one of the leading physical platforms for building the quantum repeater nodes to realize large-scale quantum networks. In a long-distance trapped-ion quantum network, it is essential to have crosstalk-free dual-type qubits: one type, called the communication qubit, to establish entangling interface with telecom photons; and the other type, called the memory qubit, to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.13369v1-abstract-full').style.display = 'inline'; document.getElementById('2405.13369v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.13369v1-abstract-full" style="display: none;"> Trapped atomic ions constitute one of the leading physical platforms for building the quantum repeater nodes to realize large-scale quantum networks. In a long-distance trapped-ion quantum network, it is essential to have crosstalk-free dual-type qubits: one type, called the communication qubit, to establish entangling interface with telecom photons; and the other type, called the memory qubit, to store quantum information immune from photon scattering under entangling attempts. Here, we report the first experimental implementation of a telecom-compatible and crosstalk-free quantum network node based on two trapped $^{40}$Ca$^{+}$ ions. The memory qubit is encoded on a long-lived metastable level to avoid crosstalk with the communication qubit encoded in another subspace of the same ion species, and a quantum wavelength conversion module is employed to generate ion-photon entanglement over a $12\,$km fiber in a heralded style. Our work therefore constitutes an important step towards the realization of quantum repeaters and long-distance quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.13369v1-abstract-full').style.display = 'none'; document.getElementById('2405.13369v1-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 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">12 pages, 12 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.09571">arXiv:2405.09571</a> <span> [<a href="https://arxiv.org/pdf/2405.09571">pdf</a>, <a href="https://arxiv.org/format/2405.09571">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Signal Processing">eess.SP</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Data Analysis, Statistics and Probability">physics.data-an</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> The Best Radar Ranging Pulse to Resolve Two Reflectors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jordan%2C+A+N">Andrew N. Jordan</a>, <a href="/search/quant-ph?searchtype=author&query=Howell%2C+J+C">John C. Howell</a>, <a href="/search/quant-ph?searchtype=author&query=Kempf%2C+A">Achim Kempf</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shunxing Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=White%2C+D">Derek White</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="2405.09571v1-abstract-short" style="display: inline;"> Previous work established fundamental bounds on subwavelength resolution for the radar range resolution problem, called superradar [Phys. Rev. Appl. 20, 064046 (2023)]. In this work, we identify the optimal waveforms for distinguishing the range resolution between two reflectors of identical strength. We discuss both the unnormalized optimal waveform as well as the best square-integrable pulse, an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09571v1-abstract-full').style.display = 'inline'; document.getElementById('2405.09571v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.09571v1-abstract-full" style="display: none;"> Previous work established fundamental bounds on subwavelength resolution for the radar range resolution problem, called superradar [Phys. Rev. Appl. 20, 064046 (2023)]. In this work, we identify the optimal waveforms for distinguishing the range resolution between two reflectors of identical strength. We discuss both the unnormalized optimal waveform as well as the best square-integrable pulse, and their variants. Using orthogonal function theory, we give an explicit algorithm to optimize the wave pulse in finite time to have the best performance. We also explore range resolution estimation with unnormalized waveforms with multi-parameter methods to also independently estimate loss and time of arrival. These results are consistent with the earlier single parameter approach of range resolution only and give deeper insight into the ranging estimation problem. Experimental results are presented using radio pulse reflections inside coaxial cables, showing robust range resolution smaller than a tenth of the inverse bandedge, with uncertainties close to the derived Cram茅r-Rao bound. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09571v1-abstract-full').style.display = 'none'; document.getElementById('2405.09571v1-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, 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">8 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/2405.09122">arXiv:2405.09122</a> <span> [<a href="https://arxiv.org/pdf/2405.09122">pdf</a>, <a href="https://arxiv.org/format/2405.09122">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 Band Structure Calculation of Semiconducting Materials on a Noisy Quantum Processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shaobo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Karim%2C+A">Akib Karim</a>, <a href="/search/quant-ph?searchtype=author&query=Quiney%2C+H+M">Harry M. Quiney</a>, <a href="/search/quant-ph?searchtype=author&query=Usman%2C+M">Muhammad Usman</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="2405.09122v1-abstract-short" style="display: inline;"> Quantum chemistry is a promising application in the era of quantum computing since the unique effects of quantum mechanics that take exponential growing resources to simulate classically are controllable on quantum computers. Fermionic degrees of freedom can be encoded efficiently onto qubits and allow for algorithms such as the Quantum Equation-of-Motion method to find the entire energy spectrum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09122v1-abstract-full').style.display = 'inline'; document.getElementById('2405.09122v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.09122v1-abstract-full" style="display: none;"> Quantum chemistry is a promising application in the era of quantum computing since the unique effects of quantum mechanics that take exponential growing resources to simulate classically are controllable on quantum computers. Fermionic degrees of freedom can be encoded efficiently onto qubits and allow for algorithms such as the Quantum Equation-of-Motion method to find the entire energy spectrum of a quantum system. In this paper, we propose the Reduced Quantum Equation-of-Motion method by reducing the dimensionality of its generalized eigenvalue equation, which results in half the measurements required compared to the Quantum Equation-of-Motion method, leading to speed up the algorithm and less noise accumulation on real devices. In particular, we analyse the performance of our method on two noise models and calculate the excitation energies of a bulk Silicon and Gallium Arsenide using our method on an IBM quantum processor. Our method is fully robust to the uniform depolarizing error and we demonstrate that the selection of suitable atomic orbital complexity could increase the robustness of our algorithm under real noise. We also find that taking the average of multiple experiments tends towards the correct energies due to the fluctuations around the exact values. Such noise resilience of our approach could be used on current quantum devices to solve quantum chemistry problems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.09122v1-abstract-full').style.display = 'none'; document.getElementById('2405.09122v1-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.08866">arXiv:2405.08866</a> <span> [<a href="https://arxiv.org/pdf/2405.08866">pdf</a>, <a href="https://arxiv.org/format/2405.08866">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Adaptation and Self-Organizing Systems">nlin.AO</span> </div> </div> <p class="title is-5 mathjax"> On the quantum origin of limit cycles, fixed points, and critical slowing down </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Dutta%2C+S">Shovan Dutta</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Haque%2C+M">Masudul Haque</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="2405.08866v1-abstract-short" style="display: inline;"> Among the most iconic features of classical dissipative dynamics are persistent limit-cycle oscillations and critical slowing down at the onset of such oscillations, where the system relaxes purely algebraically in time. On the other hand, quantum systems subject to generic Markovian dissipation decohere exponentially in time, approaching a unique steady state. Here we show how coherent limit-cycl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08866v1-abstract-full').style.display = 'inline'; document.getElementById('2405.08866v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.08866v1-abstract-full" style="display: none;"> Among the most iconic features of classical dissipative dynamics are persistent limit-cycle oscillations and critical slowing down at the onset of such oscillations, where the system relaxes purely algebraically in time. On the other hand, quantum systems subject to generic Markovian dissipation decohere exponentially in time, approaching a unique steady state. Here we show how coherent limit-cycle oscillations and algebraic decay can emerge in a quantum system governed by a Markovian master equation as one approaches the classical limit, illustrating general mechanisms using a single-spin model and a two-site lossy Bose-Hubbard model. In particular, we demonstrate that the fingerprint of a limit cycle is a slow-decaying branch with vanishing decoherence rates in the Liouville spectrum, while a power-law decay is realized by a spectral collapse at the bifurcation point. We also show how these are distinct from the case of a classical fixed point, for which the quantum spectrum is gapped and can be generated from the linearized classical dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08866v1-abstract-full').style.display = 'none'; document.getElementById('2405.08866v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 May, 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">4 pages, 6 figures + Supplement</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.05076">arXiv:2405.05076</a> <span> [<a href="https://arxiv.org/pdf/2405.05076">pdf</a>, <a href="https://arxiv.org/format/2405.05076">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Subsystem Information Capacity in Random Circuits and Hamiltonian Dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu-Qin Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shuo Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shi-Xin 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="2405.05076v2-abstract-short" style="display: inline;"> In this study, we explore the information capacity of open quantum systems, focusing on the effective channels formed by the subsystem of random quantum circuits and quantum Hamiltonian evolution. By analyzing the subsystem information capacity, which is closely linked to quantum coherent information of these effective quantum channels, we uncover a diverse range of dynamical and steady behaviors… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05076v2-abstract-full').style.display = 'inline'; document.getElementById('2405.05076v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.05076v2-abstract-full" style="display: none;"> In this study, we explore the information capacity of open quantum systems, focusing on the effective channels formed by the subsystem of random quantum circuits and quantum Hamiltonian evolution. By analyzing the subsystem information capacity, which is closely linked to quantum coherent information of these effective quantum channels, we uncover a diverse range of dynamical and steady behaviors depending on the types of evolution. Therefore, the subsystem information capacity serves as a valuable tool for studying the intrinsic nature of various dynamical phases, such as integrable, localized, thermalized, and topological systems. We also reveal the impact of different initial information encoding schemes on information dynamics including one-to-one, one-to-many, and many-to-many. To support our findings, we provide representative examples for numerical simulations, including random quantum circuits with or without mid-circuit measurements, random Clifford Floquet circuits, free and interacting Aubry-Andr茅 models, and Su-Schrieffer-Heeger models. Those numerical results are further quantitatively explained using the effective statistical model mapping and the quasiparticle picture in the cases of random circuits and non-interacting Hamiltonian dynamics, respectively. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05076v2-abstract-full').style.display = 'none'; document.getElementById('2405.05076v2-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 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">32 pages, 31 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/2405.03729">arXiv:2405.03729</a> <span> [<a href="https://arxiv.org/pdf/2405.03729">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Computational ghost imaging with hybrid transforms by integrating Hadamard, discrete cosine, and Haar matrices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Yi-Ning Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Lin-Shan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L">Liu-Ya Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Kong%2C+L">Lingxin Kong</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">Chong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+C">Cheng Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Su-Heng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+D">De-Zhong Cao</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="2405.03729v1-abstract-short" style="display: inline;"> A scenario of ghost imaging with hybrid transform approach is proposed by integrating Hadamard, discrete cosine, and Haar matrices. The measurement matrix is formed by the Kronecker product of the two different transform matrices. The image information can be conveniently reconstructed by the corresponding inverse matrices. In experiment, six hybridization sets are performed in computational ghost… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.03729v1-abstract-full').style.display = 'inline'; document.getElementById('2405.03729v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.03729v1-abstract-full" style="display: none;"> A scenario of ghost imaging with hybrid transform approach is proposed by integrating Hadamard, discrete cosine, and Haar matrices. The measurement matrix is formed by the Kronecker product of the two different transform matrices. The image information can be conveniently reconstructed by the corresponding inverse matrices. In experiment, six hybridization sets are performed in computational ghost imaging. For an object of staggered stripes, only one bucket signal survives in the Hadamard-cosine, Haar-Hadamard, and Haar-cosine hybridization sets, demonstrating flexible image compression. For a handmade windmill object, the quality factors of the reconstructed images vary with the hybridization sets. Sub-Nyquist sampling can be applied to either or both of the different transform matrices in each hybridization set in experiment. The hybridization method can be extended to apply more transforms at once. Ghost imaging with hybrid transforms may find flexible applications in image processing, such as image compression and image encryption. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.03729v1-abstract-full').style.display = 'none'; document.getElementById('2405.03729v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 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">5 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/2404.18686">arXiv:2404.18686</a> <span> [<a href="https://arxiv.org/pdf/2404.18686">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dynamic temperature compensation for wavelength-stable entangled biphoton generation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yuting Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+H">Huibo Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+X">Xiao Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Quan%2C+R">Runai Quan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+M">Mingtao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</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="2404.18686v1-abstract-short" style="display: inline;"> A dynamic temperature compensation method is presented to stabilize the wavelength of the entangled biphoton source, which is generated via the spontaneous parametric down-conversion based on a MgO: PPLN waveguide. Utilizing the dispersive Fourier transformation technique combined with a digital proportional-integral-differential algorithm, the small amount of wavelength variation can be instantly… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.18686v1-abstract-full').style.display = 'inline'; document.getElementById('2404.18686v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.18686v1-abstract-full" style="display: none;"> A dynamic temperature compensation method is presented to stabilize the wavelength of the entangled biphoton source, which is generated via the spontaneous parametric down-conversion based on a MgO: PPLN waveguide. Utilizing the dispersive Fourier transformation technique combined with a digital proportional-integral-differential algorithm, the small amount of wavelength variation can be instantly identified and then compensated with active temperature correction. The long-term wavelength stability, assessed though Allan deviation, shows nearly a hundredfold enhancement, reaching 2.00*10^(-7) at the averaging time of 10000 s. It offers a simple, ready-to-use solution for precise wavelength control in quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.18686v1-abstract-full').style.display = 'none'; document.getElementById('2404.18686v1-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 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/2404.14841">arXiv:2404.14841</a> <span> [<a href="https://arxiv.org/pdf/2404.14841">pdf</a>, <a href="https://arxiv.org/ps/2404.14841">ps</a>, <a href="https://arxiv.org/format/2404.14841">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"> Floquet dynamics of Rabi model beyond the counterrotating hybridized rotating wave method </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Han%2C+Y">Yingying Han</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuanghao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+M">Meijuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+Q">Q. Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wenxian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Weidong 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="2404.14841v1-abstract-short" style="display: inline;"> Monochromatically driven two-level systems (i.e., Rabi models) are ubiquitous in various fields of physics. Though they have been exactly solved, the physical pictures in these exact solutions are not clear. Recently, approximate analytical solutions with neat physics have been obtained by using the counterrotating hybridized rotating wave (CHRW) method, which has been proven to be effective over… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14841v1-abstract-full').style.display = 'inline'; document.getElementById('2404.14841v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.14841v1-abstract-full" style="display: none;"> Monochromatically driven two-level systems (i.e., Rabi models) are ubiquitous in various fields of physics. Though they have been exactly solved, the physical pictures in these exact solutions are not clear. Recently, approximate analytical solutions with neat physics have been obtained by using the counterrotating hybridized rotating wave (CHRW) method, which has been proven to be effective over a wider range of parameters than the previous analytical solutions. However, the CHRW depends on a parameter 尉, which has no solution in some regimes. Here we combine the double-unitary-transformation approach with the generalized Van Vleck nearly degenerate perturbation theory, and present approximate analytical results with clear physics for almost all parameter regimes, which agree well with the numerical solutions and the previous experimental results. Moreover, the dynamic frequencies of the Rabi model are regular, and the frequency with the highest Fourier amplitude changes from the Rabi frequency to 2n蠅 with driving frequency 蠅 and integer n, as the driving intensity increases from weak to deep-strong. In addition, we further explore the Floquet dynamics of the dissipative open Rabi model. Remarkably, the dissipations are tunable in the rotating frame, and the approximate analytical results obtained by our method are in good agreement with the numerical results in the strong driving regime. These results pave the way to quantum control using strong and deep-strong driving with applications in quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14841v1-abstract-full').style.display = 'none'; document.getElementById('2404.14841v1-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 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">11 pages, 7 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/2404.14727">arXiv:2404.14727</a> <span> [<a href="https://arxiv.org/pdf/2404.14727">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-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"> Pure skin effect obeying power partition in directed graphs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wenwen Liu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+O">Oubo You</a>, <a href="/search/quant-ph?searchtype=author&query=Min%2C+B">Bumki Min</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuang 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="2404.14727v1-abstract-short" style="display: inline;"> Non-Hermitian physics has received great attention recently. In particular, band structures in non-Hermitian systems can be engineered to exhibit various topological effects. Among them, one of the most intriguing phenomena is the non-Hermitian skin effect (NHSE). Here, we investigate NHSE in systems featuring directed chains or directed graphs, where the arrows denote the directions of the non-re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14727v1-abstract-full').style.display = 'inline'; document.getElementById('2404.14727v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.14727v1-abstract-full" style="display: none;"> Non-Hermitian physics has received great attention recently. In particular, band structures in non-Hermitian systems can be engineered to exhibit various topological effects. Among them, one of the most intriguing phenomena is the non-Hermitian skin effect (NHSE). Here, we investigate NHSE in systems featuring directed chains or directed graphs, where the arrows denote the directions of the non-reciprocal hopping between neighbouring nodes. We show that the systems exhibit pure skin modes with non-oscillatory wavefunctions, in contrast to previously studied NHSE. Interestingly, the sum of the decay constants along different directions for each skin mode obeys a power partition rule, i.e. their sum is a fixed value and the value of each constant only depends on the ratio between the non-reciprocal hopping parameters and is independent of detailed graph configurations. Such Pure Skin Effect (PSE) can be explained by using a generalized method for solving the Generalized Brillouin-zone with multiple bulk states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14727v1-abstract-full').style.display = 'none'; document.getElementById('2404.14727v1-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 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">poster in Piers2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.14038">arXiv:2404.14038</a> <span> [<a href="https://arxiv.org/pdf/2404.14038">pdf</a>, <a href="https://arxiv.org/format/2404.14038">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"> Accurate Chemical Reaction Modeling on Noisy Intermediate-Scale Quantum Computers Using a Noise-Resilient Wavefunction Ansatz </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+X">Xiongzhi Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+H">Huili Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shizheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+P">Pei Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Linghu%2C+K">Kehuan Linghu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+J">Jiangyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+X">Xiaoxia Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jie Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zhenyu Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+J">Jinlong 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="2404.14038v1-abstract-short" style="display: inline;"> Quantum computing is of great potential for chemical system simulations. In this study, we propose an efficient protocol of quantum computer based simulation of chemical systems which enables accurate chemical reaction modeling on noisy intermediate-scale quantum (NISQ) devices. In this protocol, we combine an correlation energy-based active orbital selection, an effective Hamiltonian from the dri… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14038v1-abstract-full').style.display = 'inline'; document.getElementById('2404.14038v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.14038v1-abstract-full" style="display: none;"> Quantum computing is of great potential for chemical system simulations. In this study, we propose an efficient protocol of quantum computer based simulation of chemical systems which enables accurate chemical reaction modeling on noisy intermediate-scale quantum (NISQ) devices. In this protocol, we combine an correlation energy-based active orbital selection, an effective Hamiltonian from the driven similarity renormalization group (DSRG) method, and a noise-resilient wavefunction ansatz. Such a combination gives a quantum resource-efficient way to accurately simulate chemical systems. The power of this protocol is demonstrated by numerical results for systems with up to tens of atoms. Modeling of a Diels-Alder (DA) reaction is also performed on a cloud-based superconducting quantum computer. These results represent an important step forward in realizing quantum utility in the NISQ era. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14038v1-abstract-full').style.display = 'none'; document.getElementById('2404.14038v1-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 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/2404.06108">arXiv:2404.06108</a> <span> [<a href="https://arxiv.org/pdf/2404.06108">pdf</a>, <a href="https://arxiv.org/format/2404.06108">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"> Symmetry-guided gradient descent for quantum neural networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bian%2C+K">Kaiming Bian</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shitao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Meng%2C+F">Fei Meng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Dahlsten%2C+O">Oscar Dahlsten</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="2404.06108v2-abstract-short" style="display: inline;"> Many supervised learning tasks have intrinsic symmetries, such as translational and rotational symmetry in image classifications. These symmetries can be exploited to enhance performance. We formulate the symmetry constraints into a concise mathematical form. We design two ways to adopt the constraints into the cost function, thereby shaping the cost landscape in favour of parameter choices which… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.06108v2-abstract-full').style.display = 'inline'; document.getElementById('2404.06108v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.06108v2-abstract-full" style="display: none;"> Many supervised learning tasks have intrinsic symmetries, such as translational and rotational symmetry in image classifications. These symmetries can be exploited to enhance performance. We formulate the symmetry constraints into a concise mathematical form. We design two ways to adopt the constraints into the cost function, thereby shaping the cost landscape in favour of parameter choices which respect the given symmetry. Unlike methods that alter the neural network circuit ansatz to impose symmetry, our method only changes the classical post-processing of gradient descent, which is simpler to implement. We call the method symmetry-guided gradient descent (SGGD). We illustrate SGGD in entanglement classification of Werner states and in a binary classification task in a 2-D feature space. In both cases, the results show that SGGD can accelerate the training, improve the generalization ability, and remove vanishing gradients, especially when the training data is biased. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.06108v2-abstract-full').style.display = 'none'; document.getElementById('2404.06108v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 August, 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> <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">Phys. Rev. A 110, 022406. Published in 5 August 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.13623">arXiv:2403.13623</a> <span> [<a href="https://arxiv.org/pdf/2403.13623">pdf</a>, <a href="https://arxiv.org/format/2403.13623">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Fast delivery of heralded atom-photon quantum correlation over 12km fiber through multiplexing enhancement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Sheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+J">Jixuan Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+Y">Yibo Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Y">Yuedong Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Y">Yukai Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+L">Luming Duan</a>, <a href="/search/quant-ph?searchtype=author&query=Pu%2C+Y">Yunfei Pu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.13623v2-abstract-short" style="display: inline;"> Distributing quantum entanglement between distant parties is a significant but difficult task in quantum information science, as it can enable numerous applications but suffers from exponential decay in the quantum channel. Quantum repeater is one of the most promising approaches towards this goal. In a quantum repeater protocol, it is essential that the entanglement generation speed within each e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13623v2-abstract-full').style.display = 'inline'; document.getElementById('2403.13623v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.13623v2-abstract-full" style="display: none;"> Distributing quantum entanglement between distant parties is a significant but difficult task in quantum information science, as it can enable numerous applications but suffers from exponential decay in the quantum channel. Quantum repeater is one of the most promising approaches towards this goal. In a quantum repeater protocol, it is essential that the entanglement generation speed within each elementary link is faster than the memory decoherence rate, to enable the scale-up of the quantum repeater by connecting neighboring repeater segments. This stringent requirement has not been implemented over a fiber of metropolitan scale so far. As a step towards this challenging goal, in this work we experimentally realize multiplexing-enhanced generation of heralded atom-photon quantum correlation over a 12km fiber. We excite the memory modes in a multiplexed quantum memory successively to generate 280 pairs of atom-photon quantum correlations with a train of photonic time-bin pulses filling the long fiber. After successful detection of a heralding signal, the excited memory mode can be identified and retrieved into idler photons on demand with either fixed or variable storage time. With the multiplexing enhancement, the heralding rate of atom-photon correlation can reach 1.95kHz, and the ratio between the quantum correlation generation rate to memory decoherence rate can be improved to 0.46 for a fiber length of 12km, which is so far the best for long fiber length (>10km) to our knowledge. This work therefore constitutes an important step towards the realization of a large-scale quantum repeater network. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13623v2-abstract-full').style.display = 'none'; document.getElementById('2403.13623v2-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">v1</span> submitted 20 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">13 pages, 10 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/2403.13011">arXiv:2403.13011</a> <span> [<a href="https://arxiv.org/pdf/2403.13011">pdf</a>, <a href="https://arxiv.org/ps/2403.13011">ps</a>, <a href="https://arxiv.org/format/2403.13011">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/10.1139/cjp-2014-0272">10.1139/cjp-2014-0272 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> 2D isotropic negative permeability in a 螞-type three-level atomic system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuang-Ying Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+S">Shun-Cai Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+A">Ai-Ling 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="2403.13011v2-abstract-short" style="display: inline;"> A approach for two-dimensional(2D) negative permeability in a $螞$-type three-level atomic system interacting with a probe magnetic and the superposition of two orthogonal standing-wave fields is proposed. Through the theoretical analysis and numerical simulation, two equally and tunable peak maxima of negative magnetic responses are observed in the x-y plane, and around the peak maxima region the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13011v2-abstract-full').style.display = 'inline'; document.getElementById('2403.13011v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.13011v2-abstract-full" style="display: none;"> A approach for two-dimensional(2D) negative permeability in a $螞$-type three-level atomic system interacting with a probe magnetic and the superposition of two orthogonal standing-wave fields is proposed. Through the theoretical analysis and numerical simulation, two equally and tunable peak maxima of negative magnetic responses are observed in the x-y plane, and around the peak maxima region the negative permeability is isotropic. A new avenue to 2D isotropic negative <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.13011v2-abstract-full').style.display = 'none'; document.getElementById('2403.13011v2-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">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">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Can. J. Phys. 93:1-5 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.12099">arXiv:2403.12099</a> <span> [<a href="https://arxiv.org/pdf/2403.12099">pdf</a>, <a href="https://arxiv.org/ps/2403.12099">ps</a>, <a href="https://arxiv.org/format/2403.12099">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/0256-307X/32/5/058104">10.1088/0256-307X/32/5/058104 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Left-handedness with three zero-absorption windows tuned by the incoherent pumping field and inter-dot tunnelings in a GaAs/AlGaAs triple quantum dots system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+S">Shun-Cai Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shuang-Ying Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Q">Qi-Xuan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+J">Jing Jia</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="2403.12099v1-abstract-short" style="display: inline;"> Left-handedness with three zero-absorption windows is achieved in a triple-quantum dot (TQD) system. With the typical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity and magnetic permeability are obtained by the adjustable incoherent pumping field and two inter-dot tunnelings. What's more, three zero-absorption windows in the left-handedness fr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.12099v1-abstract-full').style.display = 'inline'; document.getElementById('2403.12099v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.12099v1-abstract-full" style="display: none;"> Left-handedness with three zero-absorption windows is achieved in a triple-quantum dot (TQD) system. With the typical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity and magnetic permeability are obtained by the adjustable incoherent pumping field and two inter-dot tunnelings. What's more, three zero-absorption windows in the left-handedness frequency bands are observed in the TQD system. The left-handedness with zero-absorption in solid state heterostructure may solve not only the challenge in the photonic resonant scheme for left-handed materials (LHMs) but also the application limitation of the negative refractive materials with large amount of absorption. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.12099v1-abstract-full').style.display = 'none'; document.getElementById('2403.12099v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 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">5 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chin. Phys. 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