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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=Yuan%2C+H&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2502.09704">arXiv:2502.09704</a> <span> [<a href="https://arxiv.org/pdf/2502.09704">pdf</a>, <a href="https://arxiv.org/format/2502.09704">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="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optimization and Control">math.OC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> </div> </div> <p class="title is-5 mathjax"> Iterative quantum optimisation with a warm-started quantum state </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haomu Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Songqinghao Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Barnes%2C+C+H+W">Crispin H. W. Barnes</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2502.09704v1-abstract-short" style="display: inline;"> We provide a method to prepare a warm-started quantum state from measurements with an iterative framework to enhance the quantum approximate optimisation algorithm (QAOA). The numerical simulations show the method can effectively address the "stuck issue" of the standard QAOA using a single-string warm-started initial state described in [Cain et al., 2023]. When applied to the $3$-regular MaxCut p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.09704v1-abstract-full').style.display = 'inline'; document.getElementById('2502.09704v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2502.09704v1-abstract-full" style="display: none;"> We provide a method to prepare a warm-started quantum state from measurements with an iterative framework to enhance the quantum approximate optimisation algorithm (QAOA). The numerical simulations show the method can effectively address the "stuck issue" of the standard QAOA using a single-string warm-started initial state described in [Cain et al., 2023]. When applied to the $3$-regular MaxCut problem, our approach achieves an improved approximation ratio, with a lower bound that iteratively converges toward the best classical algorithms for $p=1$ standard QAOA. Additionally, in the context of the discrete global minimal variance portfolio (DGMVP) model, simulations reveal a more favourable scaling of identifying the global minimal compared to the QAOA standalone, the single-string warm-started QAOA and a classical constrained sampling approach. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2502.09704v1-abstract-full').style.display = 'none'; document.getElementById('2502.09704v1-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">feedback welcome, 13 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/2412.18398">arXiv:2412.18398</a> <span> [<a href="https://arxiv.org/pdf/2412.18398">pdf</a>, <a href="https://arxiv.org/format/2412.18398">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"> Distributed multi-parameter quantum metrology with a superconducting quantum network </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jiajian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Lingna Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Hai%2C+Y">Yong-Ju Hai</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jiawei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chu%2C+J">Ji Chu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+J">Ji Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+W">Wenhui Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+Y">Yongqi Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+J">Jiawei Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+X">Xuandong Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Tao%2C+Z">Ziyu Tao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Libo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yuanzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+W">Weijie Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Linpeng%2C+X">Xiayu Linpeng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+W">Wenhui Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Niu%2C+J">Jingjing Niu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+Y">Youpeng Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng 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="2412.18398v1-abstract-short" style="display: inline;"> Quantum metrology has emerged as a powerful tool for timekeeping, field sensing, and precision measurements within fundamental physics. With the advent of distributed quantum metrology, its capabilities have been extended to probing spatially distributed parameters across networked quantum systems. However, generating the necessary non-local entanglement remains a significant challenge, and the in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.18398v1-abstract-full').style.display = 'inline'; document.getElementById('2412.18398v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.18398v1-abstract-full" style="display: none;"> Quantum metrology has emerged as a powerful tool for timekeeping, field sensing, and precision measurements within fundamental physics. With the advent of distributed quantum metrology, its capabilities have been extended to probing spatially distributed parameters across networked quantum systems. However, generating the necessary non-local entanglement remains a significant challenge, and the inherent incompatibility in multi-parameter quantum estimation affects ultimate performance. Here we use a superconducting quantum network with low-loss interconnects to estimate multiple distributed parameters associated with non-commuting generators. By employing high-fidelity non-local entanglement across network nodes and a sequential control strategy, we accurately estimate remote vector fields and their gradients. Our approach achieves an improvement of up to 6.86 dB over classical strategy for estimating all three components of a remote vector field in terms of standard deviation. Moreover, for the estimation of gradients along two distinct directions across distributed vector fields, our distributed strategy, which utilizes non-local entanglement, outperforms local entanglement strategies, leading to a 3.44 dB reduction in the sum of variances. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.18398v1-abstract-full').style.display = 'none'; document.getElementById('2412.18398v1-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.18896">arXiv:2411.18896</a> <span> [<a href="https://arxiv.org/pdf/2411.18896">pdf</a>, <a href="https://arxiv.org/format/2411.18896">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"> Control incompatibility in multiparameter quantum metrology </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Z">Zhiyao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shilin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+L">Linmu Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Isogawa%2C+T">Takuya Isogawa</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Changhao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yu Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Guoqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.18896v1-abstract-short" style="display: inline;"> In practical applications like quantum sensing and quantum imaging, there is often a necessity to estimate multiple parameters simultaneously. Although the ultimate precision limits for single-parameter estimation are well established, the precision limit of multi-parameter estimation is much less understood. This is primarily due to the inherent incompatibility of the optimal strategies for the e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.18896v1-abstract-full').style.display = 'inline'; document.getElementById('2411.18896v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.18896v1-abstract-full" style="display: none;"> In practical applications like quantum sensing and quantum imaging, there is often a necessity to estimate multiple parameters simultaneously. Although the ultimate precision limits for single-parameter estimation are well established, the precision limit of multi-parameter estimation is much less understood. This is primarily due to the inherent incompatibility of the optimal strategies for the estimation of different parameters, particularly those pertaining to optimal control.In this study, we tackle the critical issue of control incompatibility in multi-parameter estimation by presenting explicit cases that expose this challenge. Our research not only pioneers the exploration of control incompatibility but also highlights its pivotal role in the field. Furthermore, our work offers valuable insights into how to minimize trade-offs induced by control incompatibility and enhance precision. This paves the way for future investigations into control strategies that enable optimal estimation of multiple parameters that are incompatible. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.18896v1-abstract-full').style.display = 'none'; document.getElementById('2411.18896v1-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 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/2410.21122">arXiv:2410.21122</a> <span> [<a href="https://arxiv.org/pdf/2410.21122">pdf</a>, <a href="https://arxiv.org/format/2410.21122">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum entanglement and Einstein-Podolsky-Rosen steering in magnon frequency comb </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+Q">Qianjun Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">H. Y. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yunshan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+P">Peng Yan</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="2410.21122v1-abstract-short" style="display: inline;"> Significant progress has been made for the emerging concept of magnon frequency comb (MFC) but mainly in the classical region. The quantum property of the comb structure is yet to be explored. Here we theoretically investigate the quantum fluctuations of frequency combs and demonstrate the continuous-variable quantum entanglement and Einstein-Podolsky-Rosen (EPR) steering between different teeth o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.21122v1-abstract-full').style.display = 'inline'; document.getElementById('2410.21122v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.21122v1-abstract-full" style="display: none;"> Significant progress has been made for the emerging concept of magnon frequency comb (MFC) but mainly in the classical region. The quantum property of the comb structure is yet to be explored. Here we theoretically investigate the quantum fluctuations of frequency combs and demonstrate the continuous-variable quantum entanglement and Einstein-Podolsky-Rosen (EPR) steering between different teeth of MFC. Without loss of generality, we address this issue in a hybrid magnon-skyrmion system. We observe a strong two-mode squeezed entanglement and asymmetric steering between the sum- and difference-frequency magnon teeth mediated by the skyrmion that acts as an effective reservoir to cool the Bogoliubov mode delocalized over the first-order magnon pair in MFC. Our findings show the prominent quantum nature of MFC, which has the potential to be utilized in ultrafast quantum metrology and multi-task quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.21122v1-abstract-full').style.display = 'none'; document.getElementById('2410.21122v1-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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16265">arXiv:2410.16265</a> <span> [<a href="https://arxiv.org/pdf/2410.16265">pdf</a>, <a href="https://arxiv.org/format/2410.16265">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"> Quantifying the advantages of applying quantum approximate algorithms to portfolio optimisation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haomu Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Long%2C+C+K">Christopher K. Long</a>, <a href="/search/quant-ph?searchtype=author&query=Lepage%2C+H+V">Hugo V. Lepage</a>, <a href="/search/quant-ph?searchtype=author&query=Barnes%2C+C+H+W">Crispin H. W. Barnes</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="2410.16265v1-abstract-short" style="display: inline;"> We present a quantum algorithm for portfolio optimisation. Specifically, We present an end-to-end quantum approximate optimisation algorithm (QAOA) to solve the discrete global minimum variance portfolio (DGMVP) model. This model finds a portfolio of risky assets with the lowest possible risk contingent on the number of traded assets being discrete. We provide a complete pipeline for this model an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16265v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16265v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16265v1-abstract-full" style="display: none;"> We present a quantum algorithm for portfolio optimisation. Specifically, We present an end-to-end quantum approximate optimisation algorithm (QAOA) to solve the discrete global minimum variance portfolio (DGMVP) model. This model finds a portfolio of risky assets with the lowest possible risk contingent on the number of traded assets being discrete. We provide a complete pipeline for this model and analyses its viability for noisy intermediate-scale quantum computers. We design initial states, a cost operator, and ans盲tze with hard mixing operators within a binary encoding. Further, we perform numerical simulations to analyse several optimisation routines, including layerwise optimisation, utilising COYBLA and dual annealing. Finally, we consider the impacts of thermal relaxation and stochastic measurement noise. We find dual annealing with a layerwise optimisation routine provides the most robust performance. We observe that realistic thermal relaxation noise levels preclude quantum advantage. However, stochastic measurement noise will dominate when hardware sufficiently improves. Within this regime, we numerically demonstrate a favourable scaling in the number of shots required to obtain the global minimum -- an indication of quantum advantage in portfolio optimisation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16265v1-abstract-full').style.display = 'none'; document.getElementById('2410.16265v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">35 pages, 23 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/2409.17620">arXiv:2409.17620</a> <span> [<a href="https://arxiv.org/pdf/2409.17620">pdf</a>, <a href="https://arxiv.org/format/2409.17620">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"> Digital simulation of zero-temperature spontaneous symmetry breaking in a superconducting lattice processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hu%2C+C">Chang-Kang Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+G">Guixu Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Poulsen%2C+K">Kasper Poulsen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chu%2C+J">Ji Chu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chilong Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+R">Ruiyang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haolan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+Y">Yuecheng Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zinner%2C+N+T">Nikolaj T. Zinner</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+D">Dian Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Santos%2C+A+C">Alan C. Santos</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng 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="2409.17620v1-abstract-short" style="display: inline;"> Quantum simulators are ideal platforms to investigate quantum phenomena that are inaccessible through conventional means, such as the limited resources of classical computers to address large quantum systems or due to constraints imposed by fundamental laws of nature. Here, through a digitized adiabatic evolution, we report an experimental simulation of antiferromagnetic (AFM) and ferromagnetic (F… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.17620v1-abstract-full').style.display = 'inline'; document.getElementById('2409.17620v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.17620v1-abstract-full" style="display: none;"> Quantum simulators are ideal platforms to investigate quantum phenomena that are inaccessible through conventional means, such as the limited resources of classical computers to address large quantum systems or due to constraints imposed by fundamental laws of nature. Here, through a digitized adiabatic evolution, we report an experimental simulation of antiferromagnetic (AFM) and ferromagnetic (FM) phase formation induced by spontaneous symmetry breaking (SSB) in a three-generation Cayley tree-like superconducting lattice. We develop a digital quantum annealing algorithm to mimic the system dynamics, and observe the emergence of signatures of SSB-induced phase transition through a connected correlation function. We demonstrate that the signature of phase transition from classical AFM to quantum FM happens in systems undergoing zero-temperature adiabatic evolution with only nearest-neighbor interacting systems, the shortest range of interaction possible. By harnessing properties of the bipartite Renyi entropy as an entanglement witness, we observe the formation of entangled quantum FM and AFM phases. Our results open perspectives for new advances in condensed matter physics and digitized quantum annealing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.17620v1-abstract-full').style.display = 'none'; document.getElementById('2409.17620v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.12614">arXiv:2409.12614</a> <span> [<a href="https://arxiv.org/pdf/2409.12614">pdf</a>, <a href="https://arxiv.org/format/2409.12614">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.133.160801">10.1103/PhysRevLett.133.160801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental sample-efficient quantum state tomography via parallel measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hu%2C+C">Chang-Kang Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+C">Chao Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chilong Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Che%2C+L">Liangyu Che</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+G">Guixu Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+H">Haiyang Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+G">Guantian Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haolan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+R">Ruiyang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+D">Dian Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Xin%2C+T">Tao Xin</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng 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="2409.12614v1-abstract-short" style="display: inline;"> Quantum state tomography (QST) via local measurements on reduced density matrices (LQST) is a promising approach but becomes impractical for large systems. To tackle this challenge, we developed an efficient quantum state tomography method inspired by quantum overlapping tomography [Phys. Rev. Lett. 124, 100401(2020)], which utilizes parallel measurements (PQST). In contrast to LQST, PQST signific… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.12614v1-abstract-full').style.display = 'inline'; document.getElementById('2409.12614v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.12614v1-abstract-full" style="display: none;"> Quantum state tomography (QST) via local measurements on reduced density matrices (LQST) is a promising approach but becomes impractical for large systems. To tackle this challenge, we developed an efficient quantum state tomography method inspired by quantum overlapping tomography [Phys. Rev. Lett. 124, 100401(2020)], which utilizes parallel measurements (PQST). In contrast to LQST, PQST significantly reduces the number of measurements and offers more robustness against shot noise. Experimentally, we demonstrate the feasibility of PQST in a tree-like superconducting qubit chip by designing high-efficiency circuits, preparing W states, ground states of Hamiltonians and random states, and then reconstructing these density matrices using full quantum state tomography (FQST), LQST, and PQST. Our results show that PQST reduces measurement cost, achieving fidelities of 98.68\% and 95.07\% after measuring 75 and 99 observables for 6-qubit and 9-qubit W states, respectively. Furthermore, the reconstruction of the largest density matrix of the 12-qubit W state is achieved with the similarity of 89.23\% after just measuring $243$ parallel observables, while $3^{12}=531441$ complete observables are needed for FQST. Consequently, PQST will be a useful tool for future tasks such as the reconstruction, characterization, benchmarking, and properties learning of states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.12614v1-abstract-full').style.display = 'none'; document.getElementById('2409.12614v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">To appear in PRL(2024)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 133, 160801 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.07068">arXiv:2409.07068</a> <span> [<a href="https://arxiv.org/pdf/2409.07068">pdf</a>, <a href="https://arxiv.org/format/2409.07068">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/10.1002/qute.202400094">10.1002/qute.202400094 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fully-Optimized Quantum Metrology: Framework, Tools, and Applications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qiushi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Z">Zihao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yuxiang 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="2409.07068v1-abstract-short" style="display: inline;"> This tutorial introduces a systematic approach for addressing the key question of quantum metrology: For a generic task of sensing an unknown parameter, what is the ultimate precision given a constrained set of admissible strategies. The approach outputs the maximal attainable precision (in terms of the maximum of quantum Fisher information) as a semidefinite program and optimal strategies as feas… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.07068v1-abstract-full').style.display = 'inline'; document.getElementById('2409.07068v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.07068v1-abstract-full" style="display: none;"> This tutorial introduces a systematic approach for addressing the key question of quantum metrology: For a generic task of sensing an unknown parameter, what is the ultimate precision given a constrained set of admissible strategies. The approach outputs the maximal attainable precision (in terms of the maximum of quantum Fisher information) as a semidefinite program and optimal strategies as feasible solutions thereof. Remarkably, the approach can identify the optimal precision for different sets of strategies, including parallel, sequential, quantum SWITCH-enhanced, causally superposed, and generic indefinite-causal-order strategies. The tutorial consists of a pedagogic introduction to the background and mathematical tools of optimal quantum metrology, a detailed derivation of the main approach, and various concrete examples. As shown in the tutorial, applications of the approach include, but are not limited to, strict hierarchy of strategies in noisy quantum metrology, memory effect in non-Markovian metrology, and designing optimal strategies. Compared with traditional approaches, the approach here yields the exact value of the optimal precision, offering more accurate criteria for experiments and practical applications. It also allows for the comparison between conventional strategies and the recently discovered causally-indefinite strategies, serving as a powerful tool for exploring this new area of quantum metrology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.07068v1-abstract-full').style.display = 'none'; document.getElementById('2409.07068v1-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 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">Tutorial. 38 pages, 18 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Adv. Quantum Technol. 7, 2400094 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.02282">arXiv:2408.02282</a> <span> [<a href="https://arxiv.org/pdf/2408.02282">pdf</a>, <a href="https://arxiv.org/format/2408.02282">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"> Enhanced quantum hypothesis testing via the interplay between coherent evolution and noises </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Lingna Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+M">Min Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Z">Ze Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+X">Xinhua Peng</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.02282v1-abstract-short" style="display: inline;"> Previous studies in quantum information have recognized that specific types of noise can encode information in certain applications. However, the role of noise in Quantum Hypothesis Testing (QHT), traditionally assumed to undermine performance and reduce success probability, has not been thoroughly explored. Our study bridges this gap by establishing sufficient conditions for noisy dynamics that c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.02282v1-abstract-full').style.display = 'inline'; document.getElementById('2408.02282v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.02282v1-abstract-full" style="display: none;"> Previous studies in quantum information have recognized that specific types of noise can encode information in certain applications. However, the role of noise in Quantum Hypothesis Testing (QHT), traditionally assumed to undermine performance and reduce success probability, has not been thoroughly explored. Our study bridges this gap by establishing sufficient conditions for noisy dynamics that can surpass the success probabilities achievable under noiseless (unitary) dynamics within certain time intervals. We then devise and experimentally implement a noise-assisted QHT protocol in the setting of ultralow-field nuclear magnetic resonance spin systems. Our experimental results demonstrate that the success probability of QHT under the noisy dynamics can indeed surpass the ceiling set by unitary evolution alone. Moreover, we have shown that in cases where noise initially hampers the performance, strategic application of coherent controls on the system can transform these previously detrimental noises into advantageous factors. This transformative approach demonstrates the potential to harness and leverage noise in QHT, which pushes the boundaries of QHT and general quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.02282v1-abstract-full').style.display = 'none'; document.getElementById('2408.02282v1-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 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/2407.19780">arXiv:2407.19780</a> <span> [<a href="https://arxiv.org/pdf/2407.19780">pdf</a>, <a href="https://arxiv.org/format/2407.19780">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="Disordered Systems and Neural Networks">cond-mat.dis-nn</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="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 class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.110.165130">10.1103/PhysRevB.110.165130 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Kibble-Zurek behavior in a topological phase transition with a quadratic band crossing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jinyi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shuai Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Nie%2C+X">Xiaotian Nie</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="2407.19780v2-abstract-short" style="display: inline;"> Kibble-Zurek (KZ) mechanism describes the scaling behavior when driving a system across a continuous symmetry-breaking transition. Previous studies have shown that the KZ-like scaling behavior also lies in the topological transitions in the Qi-Wu-Zhang model (2D) and the Su-Schrieffer-Heeger model (1D), although symmetry breaking does not exist here. Both models with linear band crossings give tha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.19780v2-abstract-full').style.display = 'inline'; document.getElementById('2407.19780v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.19780v2-abstract-full" style="display: none;"> Kibble-Zurek (KZ) mechanism describes the scaling behavior when driving a system across a continuous symmetry-breaking transition. Previous studies have shown that the KZ-like scaling behavior also lies in the topological transitions in the Qi-Wu-Zhang model (2D) and the Su-Schrieffer-Heeger model (1D), although symmetry breaking does not exist here. Both models with linear band crossings give that $谓=1$ and $z=1$. We wonder whether different critical exponents can be acquired in topological transitions beyond linear band crossing. In this work, we look into the KZ behavior in a topological 2D checkerboard lattice with a quadratic band crossing. We investigate from dual perspectives: momentum distribution of the Berry curvature in clean systems for simplicity, and real-space analysis of domain-like local Chern marker configurations in disordered systems, which is a more intuitive analog to conventional KZ description. In equilibrium, we find the correlation length diverges with a power $谓\simeq 1/2$. Then, by slowly quenching the system across the topological phase transition, we find that the freeze-out time $t_\mathrm{f}$ and the unfrozen length scale $尉(t_\mathrm{f})$ both satisfy the KZ scaling, verifying $z\simeq 2$. We subsequently explore KZ behavior in topological phase transitions with other higher-order band crossing and find the relationship between the critical exponents and the order. Our results extend the understanding of the KZ mechanism and non-equilibrium topological phase transitions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.19780v2-abstract-full').style.display = 'none'; document.getElementById('2407.19780v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 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">8 pages, 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 110, 165130 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.09860">arXiv:2407.09860</a> <span> [<a href="https://arxiv.org/pdf/2407.09860">pdf</a>, <a href="https://arxiv.org/format/2407.09860">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> </div> <p class="title is-5 mathjax"> Quantum Vicsek Model for Active Matter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+L+X">L. X. Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+L+T">L. T. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C+P">C. P. Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.09860v1-abstract-short" style="display: inline;"> We propose a quantum analog of the Vicsek model, consisting of an ensemble of overdamped spin$-1/2$ particles with ferromagnetic couplings, driven by a uniformly polarized magnetic field. The spontaneous magnetization of the spin components breaks the $SO(3)$ (or $SO(2)$) symmetry, inducing an ordered phase of flocking. We derive the hydrodynamic equations, similar to those formulated by Toner and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09860v1-abstract-full').style.display = 'inline'; document.getElementById('2407.09860v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.09860v1-abstract-full" style="display: none;"> We propose a quantum analog of the Vicsek model, consisting of an ensemble of overdamped spin$-1/2$ particles with ferromagnetic couplings, driven by a uniformly polarized magnetic field. The spontaneous magnetization of the spin components breaks the $SO(3)$ (or $SO(2)$) symmetry, inducing an ordered phase of flocking. We derive the hydrodynamic equations, similar to those formulated by Toner and Tu, by applying a mean-field approximation to the quantum analog model up to the next leading order. Our investigation not only establishes a microscopic connection between the Vicsek model and the Toner-Tu hydrodynamics for active matter, but also aims to inspire further studies of active matter in the quantum regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09860v1-abstract-full').style.display = 'none'; document.getElementById('2407.09860v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.03236">arXiv:2404.03236</a> <span> [<a href="https://arxiv.org/pdf/2404.03236">pdf</a>, <a href="https://arxiv.org/format/2404.03236">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1002/lpor.202401420">10.1002/lpor.202401420 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bright Heralded Single-Photon Source Saturating Theoretical Single-photon Purity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huihong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Q">Qiang Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+L">Lai Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+H">Haiqiang Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+Z">Zhiliang Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.03236v3-abstract-short" style="display: inline;"> Single-photon source is the cornerstone for modern quantum information processing. The present work derives the theoretical limit of single-photon purity for general parametric heralded single-photon sources, and subsequently demonstrates a bright, gigahertz-pulsed heralded source with the purity saturating the limit. By stimulating spontaneous four-wave mixing effect in the silicon spiral wavegui… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.03236v3-abstract-full').style.display = 'inline'; document.getElementById('2404.03236v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.03236v3-abstract-full" style="display: none;"> Single-photon source is the cornerstone for modern quantum information processing. The present work derives the theoretical limit of single-photon purity for general parametric heralded single-photon sources, and subsequently demonstrates a bright, gigahertz-pulsed heralded source with the purity saturating the limit. By stimulating spontaneous four-wave mixing effect in the silicon spiral waveguide, this on-chip source is measured to have a coincidence rate exceeding 1.5~MHz at a coincidence-to-accidental ratio (CAR) of 16.77 in the photon pair correlation experiment. The single-photon purity of this source, quantified by the heralded auto-correlation function $g^{(2)}_\text{h}(0)$, is measured by a heralded Hanbury Brown--Twiss setup to reach the theoretical limit with the lowest value of $0.00094 \pm 0.00002$ obtained at a coincidence rate of 0.8~kHz and a CAR of 2220. The performance improvements are attributed to effective spectral filtering suppressing the noise as well as the coherent pump condition helped by optical injection locking. The reported results provide a reliable standard for benchmarking heralded single-photon sources and present a state-of-the-art heralded source for quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.03236v3-abstract-full').style.display = 'none'; document.getElementById('2404.03236v3-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 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 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, 5 figures, and 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/2404.03228">arXiv:2404.03228</a> <span> [<a href="https://arxiv.org/pdf/2404.03228">pdf</a>, <a href="https://arxiv.org/format/2404.03228">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Steering nonlocality in high-speed telecommunication system without detection loophole </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Q">Qiang Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huihong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+L">Lai Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+Z">Zhiliang Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.03228v2-abstract-short" style="display: inline;"> Nonlocal correlation represents the key feature of quantum mechanics, and is an exploitable resource in quantum information processing. However, the loophole issues and the associated applicability compromises hamper the practical applications. We report the first detection-loophole-free demonstration of steering nonlocality in a fully chip-fiber telecommunication system, with an ultra-fast measur… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.03228v2-abstract-full').style.display = 'inline'; document.getElementById('2404.03228v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.03228v2-abstract-full" style="display: none;"> Nonlocal correlation represents the key feature of quantum mechanics, and is an exploitable resource in quantum information processing. However, the loophole issues and the associated applicability compromises hamper the practical applications. We report the first detection-loophole-free demonstration of steering nonlocality in a fully chip-fiber telecommunication system, with an ultra-fast measurement switching rate (2.5 GHz). In this endeavor, we propose the phase-encoding measurement scheme to adapt the system to the GHz-level modulation rate. We design and fabricate a low-loss silicon chip for efficient entanglement generation, and devise an asymmetric paradigm to mimic the measurement implementation at the steering party thus avoiding the phase-encoding loss. Consequently, we build a fiber-optic setup that can overcome the detection efficiency that is required by conclusive quantum steering with actively switched multiple measurement settings. Our setup presents an immediate platform for exploring applications based on steering nonlocality, especially for quantum communication. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.03228v2-abstract-full').style.display = 'none'; document.getElementById('2404.03228v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 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">Comments are welcome. A potential multisetting 1s-DI QKD protocol is expected to be developed. looking for collaborations</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.07089">arXiv:2402.07089</a> <span> [<a href="https://arxiv.org/pdf/2402.07089">pdf</a>, <a href="https://arxiv.org/format/2402.07089">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.109.022604">10.1103/PhysRevA.109.022604 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum multiparameter estimation enhanced by a topological phase transition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yu Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+F">Fuli Li</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.07089v1-abstract-short" style="display: inline;"> In quantum multiparameter estimation, multiple to-be-estimated parameters are encoded in a quantum dynamics system by a unitary evolution. As the parameters vary, the system may undergo a topological phase transition (TPT). In this paper, we investigate two SU(2) TPT models and propose the singular behavior of the quantum metric tensor around the TPT point as a tool for the simultaneous optimal es… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.07089v1-abstract-full').style.display = 'inline'; document.getElementById('2402.07089v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.07089v1-abstract-full" style="display: none;"> In quantum multiparameter estimation, multiple to-be-estimated parameters are encoded in a quantum dynamics system by a unitary evolution. As the parameters vary, the system may undergo a topological phase transition (TPT). In this paper, we investigate two SU(2) TPT models and propose the singular behavior of the quantum metric tensor around the TPT point as a tool for the simultaneous optimal estimation of multiple parameters. We find that the proposed TPT sensing protocol can achieve the same metrology performance as the quantum-control-enhanced one. Moreover, the probe state of the TPT sensing protocol is only the ground state of the Hamiltonian rather than the entangled state required in the control-enhanced one. In addition, an adaptive multiparameter estimation strategy is developed for updating the estimated values until the desired quantum Cram茅r-Rao bound is approached. Our work reinforces the connection between quantum multiparameter estimation and topology physics, with potential inspiration for quantum critical metrology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.07089v1-abstract-full').style.display = 'none'; document.getElementById('2402.07089v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 6 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 109, 022604 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.12457">arXiv:2401.12457</a> <span> [<a href="https://arxiv.org/pdf/2401.12457">pdf</a>, <a href="https://arxiv.org/ps/2401.12457">ps</a>, <a href="https://arxiv.org/format/2401.12457">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 gyroscopes based on double-mode surface-acoustic-wave cavities </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Y">Yuting Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+S">Shibei Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Ju%2C+F">Fangfang Ju</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.12457v1-abstract-short" style="display: inline;"> Recent progress shows that a surface-acoustic-wave (SAW) cavity can not only induce quantum acoustic dynamics but also can form optomechanical-like systems. Its operating frequencies in the microwave band make it resistant to the thermal noise of surrounding environments, while its radiation-pressure couplings make it susceptible to weak forces. Based on these advantages, we propose a gyroscope co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.12457v1-abstract-full').style.display = 'inline'; document.getElementById('2401.12457v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.12457v1-abstract-full" style="display: none;"> Recent progress shows that a surface-acoustic-wave (SAW) cavity can not only induce quantum acoustic dynamics but also can form optomechanical-like systems. Its operating frequencies in the microwave band make it resistant to the thermal noise of surrounding environments, while its radiation-pressure couplings make it susceptible to weak forces. Based on these advantages, we propose a gyroscope comprising coupled microwave-SAW cavities. In this paper, we systematically consider the three indices including range, signal-to-noise ratio, and sensitivity, which are the most important to gyroscopes but only partially considered in existing works. Additionally, we establish the fundamental limits of sensitivity when the quantum input is in the vacuum state and the squeezed vacuum state. We find that squeezing improves sensitivity and can surpass the standard quantum limit. However, this improvement can only reach up to $\sqrt{2}/2$ even as the squeezed parameter approaches infinity, which is rarely noted in recent works. Finally, we also offer analytical constraints for cooperativity and squeezed parameters. These constraints can be utilized to design gyroscopes based on coupled cavities in experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.12457v1-abstract-full').style.display = 'none'; document.getElementById('2401.12457v1-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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, 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/2312.10379">arXiv:2312.10379</a> <span> [<a href="https://arxiv.org/pdf/2312.10379">pdf</a>, <a href="https://arxiv.org/format/2312.10379">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"> Multi-parameter quantum metrology with stabilized multi-mode squeezed state </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yue Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+X">Xu Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Lingna Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+X">Xingyu Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+W">Waner Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yi Li</a>, <a href="/search/quant-ph?searchtype=author&query=Rehan%2C+K">Kamran Rehan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+M">Mingdong Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+L">Lin Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+X">Xi Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+X">Xinhua Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Y">Yiheng Lin</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="2312.10379v1-abstract-short" style="display: inline;"> Squeezing a quantum state along a specific direction has long been recognized as a crucial technique for enhancing the precision of quantum metrology by reducing parameter uncertainty. However, practical quantum metrology often involves the simultaneous estimation of multiple parameters, necessitating the use of high-quality squeezed states along multiple orthogonal axes to surpass the standard qu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10379v1-abstract-full').style.display = 'inline'; document.getElementById('2312.10379v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.10379v1-abstract-full" style="display: none;"> Squeezing a quantum state along a specific direction has long been recognized as a crucial technique for enhancing the precision of quantum metrology by reducing parameter uncertainty. However, practical quantum metrology often involves the simultaneous estimation of multiple parameters, necessitating the use of high-quality squeezed states along multiple orthogonal axes to surpass the standard quantum limit for all relevant parameters. In addition, a temporally stabilized squeezed state can provide an event-ready probe for parameters, regardless of the initial state, and robust to the timing of the state preparation process once stabilized. In this work, we generate and stabilize a two-mode squeezed state along two secular motional modes in a vibrating trapped ion with reservoir engineering, despite starting from a thermal state of the motion. Leveraging this resource, we demonstrate an estimation of two simultaneous collective displacements along the squeezed axes, achieving improvements surpassing the classical limit by up to 6.9(3) and 7.0(3) decibels (dB), respectively. Our demonstration can be readily scaled to squeezed states with even more modes. The practical implications of our findings span a wide range of applications, including quantum sensing, quantum imaging, and various fields that demand precise measurements of multiple parameters. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10379v1-abstract-full').style.display = 'none'; document.getElementById('2312.10379v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.11925">arXiv:2310.11925</a> <span> [<a href="https://arxiv.org/pdf/2310.11925">pdf</a>, <a href="https://arxiv.org/format/2310.11925">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-024-00894-x">10.1038/s41534-024-00894-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simultaneous Measurement of Multiple Incompatible Observables and Tradeoff in Multiparameter Quantum Estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Lingna Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.11925v2-abstract-short" style="display: inline;"> How well can multiple incompatible observables be implemented by a single measurement? This is a fundamental problem in quantum mechanics with wide implications for the performance optimization of numerous tasks in quantum information science. While existing studies have been mostly focusing on the approximation of two observables with a single measurement, in practice multiple observables are oft… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11925v2-abstract-full').style.display = 'inline'; document.getElementById('2310.11925v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.11925v2-abstract-full" style="display: none;"> How well can multiple incompatible observables be implemented by a single measurement? This is a fundamental problem in quantum mechanics with wide implications for the performance optimization of numerous tasks in quantum information science. While existing studies have been mostly focusing on the approximation of two observables with a single measurement, in practice multiple observables are often encountered, for which the errors of the approximations are little understood. Here we provide a framework to study the implementation of an arbitrary finite number of observables with a single measurement. Our methodology yields novel analytical bounds on the errors of these implementations, significantly advancing our understanding of this fundamental problem. Additionally, we introduce a more stringent bound utilizing semi-definite programming that, in the context of two observables, generates an analytical bound tighter than previously known bounds. The derived bounds have direct applications in assessing the trade-off between the precision of estimating multiple parameters in quantum metrology, an area with crucial theoretical and practical implications. To validate the validity of our findings, we conducted experimental verification using a superconducting quantum processor. This experimental validation not only confirms the theoretical results but also effectively bridges the gap between the derived bounds and empirical data obtained from real-world experiments. Our work paves the way for optimizing various tasks in quantum information science that involve multiple noncommutative observables. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11925v2-abstract-full').style.display = 'none'; document.getElementById('2310.11925v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Inf 10, 98 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.05592">arXiv:2309.05592</a> <span> [<a href="https://arxiv.org/pdf/2309.05592">pdf</a>, <a href="https://arxiv.org/ps/2309.05592">ps</a>, <a href="https://arxiv.org/format/2309.05592">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1367-2630/ad0a50">10.1088/1367-2630/ad0a50 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum hypothesis testing via robust quantum control </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Han Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+B">Benran Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xin Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2309.05592v1-abstract-short" style="display: inline;"> Quantum hypothesis testing plays a pivotal role in quantum technologies, making decisions or drawing conclusions about quantum systems based on observed data. Recently, quantum control techniques have been successfully applied to quantum hypothesis testing, enabling the reduction of error probabilities in the task of distinguishing magnetic fields in presence of environmental noise. In real-world… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.05592v1-abstract-full').style.display = 'inline'; document.getElementById('2309.05592v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.05592v1-abstract-full" style="display: none;"> Quantum hypothesis testing plays a pivotal role in quantum technologies, making decisions or drawing conclusions about quantum systems based on observed data. Recently, quantum control techniques have been successfully applied to quantum hypothesis testing, enabling the reduction of error probabilities in the task of distinguishing magnetic fields in presence of environmental noise. In real-world physical systems, such control is prone to various channels of inaccuracies. Therefore improving the robustness of quantum control in the context of quantum hypothesis testing is crucial. In this work, we utilize optimal control methods to compare scenarios with and without accounting for the effects of signal frequency inaccuracies. For parallel dephasing and spontaneous emission, the optimal control inherently demonstrates a certain level of robustness, while in the case of transverse dephasing with an imperfect signal, it may result in a higher error probability compared to the uncontrolled scheme. To overcome these limitations, we introduce a robust control approach optimized for a range of signal noise, demonstrating superior robustness beyond the predefined tolerance window. On average, both the optimal control and robust control show improvements over the uncontrolled schemes for various dephasing or decay rates, with the robust control yielding the lowest error probability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.05592v1-abstract-full').style.display = 'none'; document.getElementById('2309.05592v1-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> New J. Phys. 25, 113026 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.01434">arXiv:2309.01434</a> <span> [<a href="https://arxiv.org/pdf/2309.01434">pdf</a>, <a href="https://arxiv.org/ps/2309.01434">ps</a>, <a href="https://arxiv.org/format/2309.01434">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.106.042440">10.1103/PhysRevA.106.042440 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum error pre-compensation for quantum noisy channels </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chengjie Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Liangsheng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+G">Guodong Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+R">Runyao 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="2309.01434v1-abstract-short" style="display: inline;"> Most previous efforts of quantum error correction focused on either extending classical error correction schemes to the quantum regime by performing a perfect correction on a subset of errors, or seeking a recovery operation to maximize the fidelity between a input state and its corresponding output state of a noisy channel. There are few results concerning quantum error pre-compensation. Here we… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.01434v1-abstract-full').style.display = 'inline'; document.getElementById('2309.01434v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.01434v1-abstract-full" style="display: none;"> Most previous efforts of quantum error correction focused on either extending classical error correction schemes to the quantum regime by performing a perfect correction on a subset of errors, or seeking a recovery operation to maximize the fidelity between a input state and its corresponding output state of a noisy channel. There are few results concerning quantum error pre-compensation. Here we design an error pre-compensated input state for an arbitrary quantum noisy channel and a given target output state. By following a procedure, the required input state, if it exists, can be analytically obtained in single-partite systems. Furthermore, we also present semidefinite programs to numerically obtain the error pre-compensated input states with maximal fidelities between the target state and the output state. The numerical results coincide with the analytical results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.01434v1-abstract-full').style.display = 'none'; document.getElementById('2309.01434v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 3 figures,</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 106, 042440 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.11590">arXiv:2307.11590</a> <span> [<a href="https://arxiv.org/pdf/2307.11590">pdf</a>, <a href="https://arxiv.org/ps/2307.11590">ps</a>, <a href="https://arxiv.org/format/2307.11590">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 LiDAR with Frequency Modulated Continuous Wave </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+M">Ming-Da Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Z">Zhan-Feng Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hong-Yi Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zuo%2C+Y">Ying Zuo</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Peng Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hai-Dong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Li-Jian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+Q">Qi Qin</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.11590v1-abstract-short" style="display: inline;"> The range and speed of a moving object can be ascertained using the sensing technique known as light detection and ranging (LiDAR). It has recently been suggested that quantum LiDAR, which uses entangled states of light, can enhance the capabilities of LiDAR. Entangled pulsed light is used in prior quantum LiDAR approaches to assess both range and velocity at the same time using the pulses' time o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.11590v1-abstract-full').style.display = 'inline'; document.getElementById('2307.11590v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.11590v1-abstract-full" style="display: none;"> The range and speed of a moving object can be ascertained using the sensing technique known as light detection and ranging (LiDAR). It has recently been suggested that quantum LiDAR, which uses entangled states of light, can enhance the capabilities of LiDAR. Entangled pulsed light is used in prior quantum LiDAR approaches to assess both range and velocity at the same time using the pulses' time of flight and Doppler shift. The entangled pulsed light generation and detection, which are crucial for pulsed quantum LiDAR, are often inefficient. Here, we study a quantum LiDAR that operates on a frequency-modulated continuous wave (FMCW), as opposed to pulses. We first outline the design of the quantum FMCW LiDAR using entangled frequency-modulated photons in a Mach-Zehnder interferometer, and we demonstrate how it can increase accuracy and resolution for range and velocity measurements by $\sqrt{n}$ and $n$, respectively, with $n$ entangled photons. We also demonstrate that quantum FMCW LiDAR may perform simultaneous measurements of the range and velocity without the need for quantum pulsed compression, which is necessary in pulsed quantum LiDAR. Since the generation of entangled photons is the only inefficient nonlinear optical process needed, the quantum FMCW LiDAR is better suited for practical implementations. Additionally, most measurements in the quantum FMCW LiDAR can be carried out electronically by down-converting optical signal to microwave region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.11590v1-abstract-full').style.display = 'none'; document.getElementById('2307.11590v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.17610">arXiv:2305.17610</a> <span> [<a href="https://arxiv.org/pdf/2305.17610">pdf</a>, <a href="https://arxiv.org/format/2305.17610">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Composite Biased Rotations for Precise Raman Control of Spinor Matterwaves </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qiu%2C+L">Liyang Qiu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+S">Saijun Wu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.17610v2-abstract-short" style="display: inline;"> Precise control of hyperfine matterwaves via Raman excitations is instrumental to a class of atom-based quantum technology. We investigate the Raman spinor control technique for alkaline atoms in an intermediate regime of single-photon detuning where a choice can be made to balance the Raman excitation power efficiency with the control speed, excited-state adiabatic elimination, and spontaneous em… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17610v2-abstract-full').style.display = 'inline'; document.getElementById('2305.17610v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.17610v2-abstract-full" style="display: none;"> Precise control of hyperfine matterwaves via Raman excitations is instrumental to a class of atom-based quantum technology. We investigate the Raman spinor control technique for alkaline atoms in an intermediate regime of single-photon detuning where a choice can be made to balance the Raman excitation power efficiency with the control speed, excited-state adiabatic elimination, and spontaneous emission suppression requirements. Within the regime, rotations of atomic spinors by the Raman coupling are biased by substantial light shifts. Taking advantage of the fixed bias angle, we show that composite biased rotations can be optimized to enable precise ensemble spinor matterwave control within nanoseconds, even for multiple Zeeman pseudo-spins defined on the hyperfine ground states and when the laser illumination is strongly inhomogeneous. Our scheme fills a technical gap in light pulse atom interferometry, for achieving high speed Raman spinor matterwave control with moderate laser power. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.17610v2-abstract-full').style.display = 'none'; document.getElementById('2305.17610v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 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/2305.01946">arXiv:2305.01946</a> <span> [<a href="https://arxiv.org/pdf/2305.01946">pdf</a>, <a href="https://arxiv.org/format/2305.01946">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.19.054048">10.1103/PhysRevApplied.19.054048 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Controlled entanglement source for quantum cryptography </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Q">Qiang Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huihong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yuanbin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+L">Lai Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y">Yuanfei Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+H">Haiqiang Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+Z">Zhiliang Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.01946v1-abstract-short" style="display: inline;"> Quantum entanglement has become an essential resource in quantum information processing. Existing works employ entangled quantum states to perform various tasks, while little attention is paid to the control of the resource. In this work, we propose a simple protocol to upgrade an entanglement source with access control through phase randomization at the optical pump. The enhanced source can effec… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.01946v1-abstract-full').style.display = 'inline'; document.getElementById('2305.01946v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.01946v1-abstract-full" style="display: none;"> Quantum entanglement has become an essential resource in quantum information processing. Existing works employ entangled quantum states to perform various tasks, while little attention is paid to the control of the resource. In this work, we propose a simple protocol to upgrade an entanglement source with access control through phase randomization at the optical pump. The enhanced source can effectively control all users in utilizing the entanglement resource to implement quantum cryptography. In addition, we show this control can act as a practical countermeasure against memory attack on device-independent quantum key distribution at a negligible cost. To demonstrate the feasibility of our protocol, we implement an experimental setup using just off-the-shelf components and characterize its performance accordingly. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.01946v1-abstract-full').style.display = 'none'; document.getElementById('2305.01946v1-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 7 figures, comments are welcome! Looking forward to collaborations!</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.06915">arXiv:2304.06915</a> <span> [<a href="https://arxiv.org/pdf/2304.06915">pdf</a>, <a href="https://arxiv.org/format/2304.06915">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"> Quasi-binary encoding based quantum alternating operator ansatz </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+B">Bingren Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hanqing Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haomu Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+L">Lei Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xin 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="2304.06915v2-abstract-short" style="display: inline;"> This paper proposes a quasi-binary encoding based algorithm for solving a specific quadratic optimization models with discrete variables, in the quantum approximate optimization algorithm (QAOA) framework. The quadratic optimization model has three constraints: 1. Discrete constraint, the variables are required to be integers. 2. Bound constraint, each variable is required to be greater than or eq… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.06915v2-abstract-full').style.display = 'inline'; document.getElementById('2304.06915v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.06915v2-abstract-full" style="display: none;"> This paper proposes a quasi-binary encoding based algorithm for solving a specific quadratic optimization models with discrete variables, in the quantum approximate optimization algorithm (QAOA) framework. The quadratic optimization model has three constraints: 1. Discrete constraint, the variables are required to be integers. 2. Bound constraint, each variable is required to be greater than or equal to an integer and less than or equal to another integer. 3. Sum constraint, the sum of all variables should be a given integer. To solve this optimization model, we use quasi-binary encoding to encode the variables. For an integer variable with upper bound $U_i$ and lower bound $L_i$, this encoding method can use at most $2\log_2 (U_i-L_i+1)$ qubits to encode the variable. Moreover, we design a mixing operator specifically for this encoding to satisfy the hard constraint model. In the hard constraint model, the quantum state always satisfies the constraints during the evolution, and no penalty term is needed in the objective function. In other parts of the QAOA framework, we also incorporate ideas such as CVaR-QAOA and parameter scheduling methods into our QAOA algorithm. In the financial field, by introducing precision, portfolio optimization problems can be reduced to the above model. We will use portfolio optimization cases for numerical simulation. We design an iterative method to solve the problem of coarse precision caused by insufficient qubits of the simulators or quantum computers. This iterative method can refine the precision by multiple few-qubit experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.06915v2-abstract-full').style.display = 'none'; document.getElementById('2304.06915v2-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 12 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 90C27; 81P68; m91B28 <span class="has-text-black-bis has-text-weight-semibold">ACM Class:</span> G.1.6; I.1.2 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.16313">arXiv:2303.16313</a> <span> [<a href="https://arxiv.org/pdf/2303.16313">pdf</a>, <a href="https://arxiv.org/format/2303.16313">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0152543">10.1063/5.0152543 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tutorial: Nonlinear magnonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+S">Shasha Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhenyu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yipu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+F">Fengxiao Sun</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Q">Qiongyi He</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+P">Peng Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">H. Y. Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.16313v1-abstract-short" style="display: inline;"> Nonlinear magnonics studies the nonlinear interaction between magnons and other physical platforms (phonon, photon, qubit, spin texture) to generate novel magnon states for information processing. In this tutorial, we first introduce the nonlinear interactions of magnons in pure magnetic systems and hybrid magnon-phonon and magnon-photon systems. Then we show how these nonlinear interactions can g… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.16313v1-abstract-full').style.display = 'inline'; document.getElementById('2303.16313v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.16313v1-abstract-full" style="display: none;"> Nonlinear magnonics studies the nonlinear interaction between magnons and other physical platforms (phonon, photon, qubit, spin texture) to generate novel magnon states for information processing. In this tutorial, we first introduce the nonlinear interactions of magnons in pure magnetic systems and hybrid magnon-phonon and magnon-photon systems. Then we show how these nonlinear interactions can generate exotic magnonic phenomena. In the classical regime, we will cover the parametric excitation of magnons, bistability and multistability, and the magnonic frequency comb. In the quantum regime, we will discuss the single magnon state, Schr枚dinger cat state and the entanglement and quantum steering among magnons, photons and phonons. The applications of the hybrid magnonics systems in quantum transducer and sensing will also be presented. Finally, we outlook the future development direction of nonlinear magnonics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.16313v1-abstract-full').style.display = 'none'; document.getElementById('2303.16313v1-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 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">50 pages, 26 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Appl. Phys. 134, 151101 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.06310">arXiv:2302.06310</a> <span> [<a href="https://arxiv.org/pdf/2302.06310">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> </div> </div> <p class="title is-5 mathjax"> Efficient real-time spin readout of nitrogen-vacancy centers based on Bayesian estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jixing Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tianzheng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+S">Sigang Xia</a>, <a href="/search/quant-ph?searchtype=author&query=Bian%2C+G">Guodong Bian</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+P">Pengcheng Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Mingxin Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Sixian Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangyun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shaoda Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Heng Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.06310v1-abstract-short" style="display: inline;"> In this work, to improve the spin readout efficiency of the nitrogen vacancy (NV) center, a real-time Bayesian estimation algorithm is proposed, which combines both the prior probability distribution and the fluorescence likelihood function established by the implementation of the NV center dynamics model. The theoretical surpass of the Cramer-Rao lower bound of the readout variance and the improv… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06310v1-abstract-full').style.display = 'inline'; document.getElementById('2302.06310v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.06310v1-abstract-full" style="display: none;"> In this work, to improve the spin readout efficiency of the nitrogen vacancy (NV) center, a real-time Bayesian estimation algorithm is proposed, which combines both the prior probability distribution and the fluorescence likelihood function established by the implementation of the NV center dynamics model. The theoretical surpass of the Cramer-Rao lower bound of the readout variance and the improvement of the readout efficiency in the simulation indicate that our approach is an appealing alternative to the conventional photon summation method. The Bayesian real-time estimation readout was experimentally realized by combining a high-performance acquisition and processing hardware, and the Rabi oscillation experiments divulged that the signal-to-noise ratio of our approach was improved by 28.6%. Therefore, it is anticipated that the employed Bayesian estimation readout will effectively present superior sensing capabilities of the NV ensemble, and foster the further development of compact and scalable quantum sensors and consequently novel quantum information processing devices on a monolithic platform. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.06310v1-abstract-full').style.display = 'none'; document.getElementById('2302.06310v1-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 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.06090">arXiv:2301.06090</a> <span> [<a href="https://arxiv.org/pdf/2301.06090">pdf</a>, <a href="https://arxiv.org/format/2301.06090">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 class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevResearch.5.L032016">10.1103/PhysRevResearch.5.L032016 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Extracting the Quantum Geometric Tensor of an Optical Raman Lattice by Bloch State Tomography </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yi%2C+C">Chang-Rui Yi</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+J">Jinlong Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Jiao%2C+R">Rui-Heng Jiao</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yu-Meng Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jin-Yi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shuai Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2301.06090v2-abstract-short" style="display: inline;"> In Hilbert space, the geometry of the quantum state is identified by the quantum geometric tensor (QGT), whose imaginary part is the Berry curvature and real part is the quantum metric tensor. Here, we propose and experimentally implement a complete Bloch state tomography to directly measure eigenfunction of an optical Raman lattice for ultracold atoms. Through the measured eigenfunction, the dist… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.06090v2-abstract-full').style.display = 'inline'; document.getElementById('2301.06090v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.06090v2-abstract-full" style="display: none;"> In Hilbert space, the geometry of the quantum state is identified by the quantum geometric tensor (QGT), whose imaginary part is the Berry curvature and real part is the quantum metric tensor. Here, we propose and experimentally implement a complete Bloch state tomography to directly measure eigenfunction of an optical Raman lattice for ultracold atoms. Through the measured eigenfunction, the distribution of the complete QGT in the Brillouin zone is reconstructed, with which the topological invariants are extracted by the Berry curvature and the distances of quantum states in momentum space are measured by the quantum metric tensor. Further, we experimentally test a predicted inequality between the Berry curvature and quantum metric tensor, which reveals a deep connection between topology and geometry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.06090v2-abstract-full').style.display = 'none'; document.getElementById('2301.06090v2-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 5, L032016 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.12296">arXiv:2211.12296</a> <span> [<a href="https://arxiv.org/pdf/2211.12296">pdf</a>, <a href="https://arxiv.org/format/2211.12296">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"> Variational Quantum Metrology with Loschmidt Echo </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Ran Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+Z">Ze Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiaodong Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuchen Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Hui Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yuquan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</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="2211.12296v1-abstract-short" style="display: inline;"> By utilizing quantum mechanical effects, such as superposition and entanglement, quantum metrology promises higher precision than the classical strategies. It is, however, practically challenging to realize the quantum advantages. This is mainly due to the difficulties in engineering non-classical probe state and performing nontrivial measurement in practise, particularly with a large number of pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.12296v1-abstract-full').style.display = 'inline'; document.getElementById('2211.12296v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.12296v1-abstract-full" style="display: none;"> By utilizing quantum mechanical effects, such as superposition and entanglement, quantum metrology promises higher precision than the classical strategies. It is, however, practically challenging to realize the quantum advantages. This is mainly due to the difficulties in engineering non-classical probe state and performing nontrivial measurement in practise, particularly with a large number of particles. Here we propose a scalable scheme with a symmetrical variational quantum circuit which, same as the Loschmidt echo, consists of a forward and a backward evolution. We show that in this scheme the quantum Fisher information, which quantifies the precision limit, can be efficiently obtained from a measurement signal of the Loschmidt echo. We experimentally implement the scheme on an ensemble of 10-spin quantum processor and successfully achieves a precision near the theoretical limit which outperforms the standard quantum limit with 12.4 dB. The scheme can be efficiently implemented on various noisy intermediate-scale quantum devices which provides a promising routine to demonstrate quantum advantages. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.12296v1-abstract-full').style.display = 'none'; document.getElementById('2211.12296v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.04739">arXiv:2211.04739</a> <span> [<a href="https://arxiv.org/pdf/2211.04739">pdf</a>, <a href="https://arxiv.org/format/2211.04739">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.043201">10.1103/PhysRevLett.130.043201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tuning anomalous Floquet topological bands with ultracold atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jin-Yi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yi%2C+C">Chang-Rui Yi</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Long Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiao%2C+R">Rui-Heng Jiao</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+K">Kai-Ye Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xiong-Jun Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shuai Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.04739v1-abstract-short" style="display: inline;"> The Floquet engineering opens the way to create new topological states without counterparts in static systems. Here, we report the experimental realization and characterization of new anomalous topological states with high-precision Floquet engineering for ultracold atoms trapped in a shaking optical Raman lattice. The Floquet band topology is manipulated by tuning the driving-induced band crossin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.04739v1-abstract-full').style.display = 'inline'; document.getElementById('2211.04739v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.04739v1-abstract-full" style="display: none;"> The Floquet engineering opens the way to create new topological states without counterparts in static systems. Here, we report the experimental realization and characterization of new anomalous topological states with high-precision Floquet engineering for ultracold atoms trapped in a shaking optical Raman lattice. The Floquet band topology is manipulated by tuning the driving-induced band crossings referred to as band inversion surfaces (BISs), whose configurations fully characterize the topology of the underlying states. We uncover various exotic anomalous topological states by measuring the configurations of BISs which correspond to the bulk Floquet topology. In particular, we identify an unprecedented anomalous Floquet valley-Hall state that possesses anomalous helicallike edge modes protected by valleys and a chiral state with high Chern number. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.04739v1-abstract-full').style.display = 'none'; document.getElementById('2211.04739v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 130, 043201 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.02961">arXiv:2209.02961</a> <span> [<a href="https://arxiv.org/pdf/2209.02961">pdf</a>, <a href="https://arxiv.org/format/2209.02961">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.106.224422">10.1103/PhysRevB.106.224422 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Master equation approach to magnon relaxation and dephasing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">H. Y. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Sterk%2C+W+P">W. P. Sterk</a>, <a href="/search/quant-ph?searchtype=author&query=Kamra%2C+A">Akashdeep Kamra</a>, <a href="/search/quant-ph?searchtype=author&query=Duine%2C+R+A">Rembert A. Duine</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="2209.02961v1-abstract-short" style="display: inline;"> There has been a recent upsurge of interest in the quantum properties of magnons for quantum information processing. An important issue is to examine the stability of quantum states of magnons against various relaxation and dephasing channels. Since the interaction of magnons in magnetic systems may fall in the ultra-strong and even deep-strong coupling regimes, the relaxation process of magnon st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.02961v1-abstract-full').style.display = 'inline'; document.getElementById('2209.02961v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.02961v1-abstract-full" style="display: none;"> There has been a recent upsurge of interest in the quantum properties of magnons for quantum information processing. An important issue is to examine the stability of quantum states of magnons against various relaxation and dephasing channels. Since the interaction of magnons in magnetic systems may fall in the ultra-strong and even deep-strong coupling regimes, the relaxation process of magnon states is quite different from the more common quantum optical systems. Here we study the relaxation and dephasing of magnons based on the Lindblad formalism and derive a generalized master equation that describes the quantum dynamics of magnons. Employing this master equation, we identify two distinct dissipation channels for squeezed magnons, i.e., the local dissipation and collective dissipation, which play a role for both ferromagnets and antiferromagnets. The local dissipation is caused by the independent exchange of angular momentum between the magnonic system and the environment, while the collective dissipation is dressed by the parametric interactions of magnons and it enhances the quantumness and thermal stability of squeezed magnons. Further, we show how this formalism can be applied to study the pure dephasing of magnons caused by four-magnon scattering and magnon-phonon interactions. Our results provide the theoretical tools to study the decoherence of magnons within a full quantum-mechanical framework and further benefit the use of quantum states of magnons for information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.02961v1-abstract-full').style.display = 'none'; document.getElementById('2209.02961v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </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, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review B 106, 224422 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.13095">arXiv:2206.13095</a> <span> [<a href="https://arxiv.org/pdf/2206.13095">pdf</a>, <a href="https://arxiv.org/format/2206.13095">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.128.250502">10.1103/PhysRevLett.128.250502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Information geometry under hierarchical quantum measurement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.13095v1-abstract-short" style="display: inline;"> In most quantum technologies, measurements need to be performed on the parametrized quantum states to transform the quantum information to classical information. The measurements, however, inevitably distort the information. The characterization of the discrepancy is an important subject in quantum information science, which plays a key role in understanding the difference between the structures o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.13095v1-abstract-full').style.display = 'inline'; document.getElementById('2206.13095v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.13095v1-abstract-full" style="display: none;"> In most quantum technologies, measurements need to be performed on the parametrized quantum states to transform the quantum information to classical information. The measurements, however, inevitably distort the information. The characterization of the discrepancy is an important subject in quantum information science, which plays a key role in understanding the difference between the structures of the quantum and classical information. Here we analyze the discrepancy in terms of the Fisher information metric and present a framework that can provide analytical bounds on the difference under hierarchical quantum measurements. Specifically, we present a set of analytical bounds on the difference between the quantum and classical Fisher information metric under hierarchical p-local quantum measurements, which are measurements that can be performed collectively on at most p copies of quantum states. The results can be directly transformed to the precision limit in multi-parameter quantum metrology, which leads to characterizations of the tradeoff among the precision of different parameters. The framework also provides a coherent picture for various existing results by including them as special cases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.13095v1-abstract-full').style.display = 'none'; document.getElementById('2206.13095v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </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">This is a short version of arXiv:2109.05807</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 128, 250502 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.11166">arXiv:2206.11166</a> <span> [<a href="https://arxiv.org/pdf/2206.11166">pdf</a>, <a href="https://arxiv.org/format/2206.11166">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 Logarithm Depth Quantum Converter: From One-hot Encoding to Binary Encoding </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+B">Bingren Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hanqing Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haomu Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+L">Lei Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xin 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="2206.11166v2-abstract-short" style="display: inline;"> Within the quantum computing, there are two ways to encode a normalized vector $\{ 伪_i \}$. They are one-hot encoding and binary coding. The one-hot encoding state is denoted as $\left | 蠄_O^{(N)} \right \rangle=\sum_{i=0}^{N-1} 伪_i \left |0 \right \rangle^{\otimes N-i-1} \left |1 \right \rangle \left |0 \right \rangle ^{\otimes i}$ and the binary encoding state is denoted as… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.11166v2-abstract-full').style.display = 'inline'; document.getElementById('2206.11166v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.11166v2-abstract-full" style="display: none;"> Within the quantum computing, there are two ways to encode a normalized vector $\{ 伪_i \}$. They are one-hot encoding and binary coding. The one-hot encoding state is denoted as $\left | 蠄_O^{(N)} \right \rangle=\sum_{i=0}^{N-1} 伪_i \left |0 \right \rangle^{\otimes N-i-1} \left |1 \right \rangle \left |0 \right \rangle ^{\otimes i}$ and the binary encoding state is denoted as $\left | 蠄_B^{(N)} \right \rangle=\sum_{i=0}^{N-1} 伪_i \left |b_i \right \rangle$, where $b_i$ is interpreted in binary of $i$ as the tensor product sequence of qubit states. In this paper, we present a method converting between the one-hot encoding state and the binary encoding state by taking the Edick state as the transition state, where the Edick state is defined as $\left | 蠄_E^{(N)} \right \rangle=\sum_{i=0}^{N-1} 伪_i \left |0 \right \rangle^{\otimes N-i-1} \left |1 \right \rangle ^{\otimes i}$. Compared with the early work, our circuit achieves the exponential speedup with $O(\log^2 N)$ depth and $O(N)$ size. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.11166v2-abstract-full').style.display = 'none'; document.getElementById('2206.11166v2-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 figures, 17 pages</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 68Q12 <span class="has-text-black-bis has-text-weight-semibold">ACM Class:</span> F.1.0 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.07471">arXiv:2206.07471</a> <span> [<a href="https://arxiv.org/pdf/2206.07471">pdf</a>, <a href="https://arxiv.org/format/2206.07471">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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"> Dissipation-free modes in dissipative systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=van+Seters%2C+D">Daan van Seters</a>, <a href="/search/quant-ph?searchtype=author&query=Ludwig%2C+T">Tim Ludwig</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">Huaiyang Y. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Duine%2C+R+A">Rembert A. Duine</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="2206.07471v1-abstract-short" style="display: inline;"> The coupling between a system and its environment (or bath) always leads to dissipation. We show, however, that a system composed of two subsystems can have a dissipation-free mode, if the bath is shared between the two subsystems. Reading in reverse, a shared bath does not contribute to the dissipation of all modes. As a key example, we consider a simple model for a two-sublattice antiferromagnet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.07471v1-abstract-full').style.display = 'inline'; document.getElementById('2206.07471v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.07471v1-abstract-full" style="display: none;"> The coupling between a system and its environment (or bath) always leads to dissipation. We show, however, that a system composed of two subsystems can have a dissipation-free mode, if the bath is shared between the two subsystems. Reading in reverse, a shared bath does not contribute to the dissipation of all modes. As a key example, we consider a simple model for a two-sublattice antiferromagnet, where the environment is modeled by a bath that is shared between the two sublattice magnetizations. In our model, we find that the N茅el order parameter is a dissipation-free mode. For antiferromagnets, our results offer an explanation for why the dissipation rate of the N茅el vector is typically much lower than that of the average magnetization. In general, our results suggest a way to reduce dissipation (and decoherence) for some modes in composite systems, which could have experimental and technological applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.07471v1-abstract-full').style.display = 'none'; document.getElementById('2206.07471v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 2 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.15588">arXiv:2205.15588</a> <span> [<a href="https://arxiv.org/pdf/2205.15588">pdf</a>, <a href="https://arxiv.org/format/2205.15588">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computational Physics">physics.comp-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevResearch.4.043057">10.1103/PhysRevResearch.4.043057 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> QuanEstimation: An open-source toolkit for quantum parameter estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+M">Mao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Huai-Ming Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoguang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Demkowicz-Dobrza%C5%84ski%2C+R">Rafa艂 Demkowicz-Dobrza艅ski</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jing 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="2205.15588v3-abstract-short" style="display: inline;"> Quantum parameter estimation promises a high-precision measurement in theory, however, how to design the optimal scheme in a specific scenario, especially under a practical condition, is still a serious problem that needs to be solved case by case due to the existence of multiple mathematical bounds and optimization methods. Depending on the scenario considered, different bounds may be more or les… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.15588v3-abstract-full').style.display = 'inline'; document.getElementById('2205.15588v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.15588v3-abstract-full" style="display: none;"> Quantum parameter estimation promises a high-precision measurement in theory, however, how to design the optimal scheme in a specific scenario, especially under a practical condition, is still a serious problem that needs to be solved case by case due to the existence of multiple mathematical bounds and optimization methods. Depending on the scenario considered, different bounds may be more or less suitable, both in terms of computational complexity and the tightness of the bound itself. At the same time, the metrological schemes provided by different optimization methods need to be tested against realization complexity, robustness, etc. Hence, a comprehensive toolkit containing various bounds and optimization methods is essential for the scheme design in quantum metrology. To fill this vacancy, here we present a Python-Julia-based open-source toolkit for quantum parameter estimation, which includes many well-used mathematical bounds and optimization methods. Utilizing this toolkit, all procedures in the scheme design, such as the optimizations of the probe state, control and measurement, can be readily and efficiently performed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.15588v3-abstract-full').style.display = 'none'; document.getElementById('2205.15588v3-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </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">40 pages, 20 figures. Close to the published version. Corresponding package version: v0.2.0 (Python) v0.1.3 (Julia)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 4, 043057 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.09758">arXiv:2203.09758</a> <span> [<a href="https://arxiv.org/pdf/2203.09758">pdf</a>, <a href="https://arxiv.org/format/2203.09758">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.070803">10.1103/PhysRevLett.130.070803 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal Strategies of Quantum Metrology with a Strict Hierarchy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qiushi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Z">Zihao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yuxiang 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="2203.09758v3-abstract-short" style="display: inline;"> One of the main quests in quantum metrology is to attain the ultimate precision limit with given resources, where the resources are not only of the number of queries, but more importantly of the allowed strategies. With the same number of queries, the restrictions on the strategies constrain the achievable precision. In this work, we establish a systematic framework to identify the ultimate precis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09758v3-abstract-full').style.display = 'inline'; document.getElementById('2203.09758v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.09758v3-abstract-full" style="display: none;"> One of the main quests in quantum metrology is to attain the ultimate precision limit with given resources, where the resources are not only of the number of queries, but more importantly of the allowed strategies. With the same number of queries, the restrictions on the strategies constrain the achievable precision. In this work, we establish a systematic framework to identify the ultimate precision limit of different families of strategies, including the parallel, the sequential, and the indefinite-causal-order strategies, and provide an efficient algorithm that determines an optimal strategy within the family of strategies under consideration. With our framework, we show there exists a strict hierarchy of the precision limits for different families of strategies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09758v3-abstract-full').style.display = 'none'; document.getElementById('2203.09758v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </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 + 23 pages, 10 figures; close to the published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 130, 070803 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.01435">arXiv:2202.01435</a> <span> [<a href="https://arxiv.org/pdf/2202.01435">pdf</a>, <a href="https://arxiv.org/format/2202.01435">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-022-34727-2">10.1038/s41467-022-34727-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Engineering superconducting qubits to reduce quasiparticles and charge noise </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pan%2C+X">Xianchuang Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Y">Yuxuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haolan Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Nie%2C+L">Lifu Nie</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+W">Weiwei Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Libo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jian Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Song Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Z+H">Zhi Hao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Catelani%2C+G">Gianluigi Catelani</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+L">Ling Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+F">Fei Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+D">Dapeng 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="2202.01435v2-abstract-short" style="display: inline;"> Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.01435v2-abstract-full').style.display = 'inline'; document.getElementById('2202.01435v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.01435v2-abstract-full" style="display: none;"> Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence devices is therefore highly desirable. Here we experimentally demonstrate how to control quasiparticle generation by downsizing the qubit, capping it with a metallic cover, and equipping it with suitable quasiparticle traps. Using a flip-chip design, we shape the electromagnetic environment of the qubit above the superconducting gap, inhibiting quasiparticle poisoning. Our findings support the hypothesis that quasiparticle generation is dominated by the breaking of Cooper pairs at the junction, as a result of photon absorption by the antenna-like qubit structure. We achieve record low charge-parity switching rate (<1Hz). Our aluminium devices also display improved stability with respect to discrete charging events. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.01435v2-abstract-full').style.display = 'none'; document.getElementById('2202.01435v2-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Commun. 13, 7196 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.06637">arXiv:2201.06637</a> <span> [<a href="https://arxiv.org/pdf/2201.06637">pdf</a>, <a href="https://arxiv.org/format/2201.06637">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.106.L100403">10.1103/PhysRevB.106.L100403 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pure dephasing of magnonic quantum states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">H. Y. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Sterk%2C+W+P">W. P. Sterk</a>, <a href="/search/quant-ph?searchtype=author&query=Kamra%2C+A">Akashdeep Kamra</a>, <a href="/search/quant-ph?searchtype=author&query=Duine%2C+R+A">Rembert A. Duine</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="2201.06637v1-abstract-short" style="display: inline;"> For a wide range of nonclassical magnonic states that have been proposed and demonstrated recently, a new time scale besides the magnon lifetime - the magnon dephasing time - becomes important, but this time scale is rarely studied. Considering exchange interaction and spin-phonon coupling, we evaluate the pure magnon dephasing time and find it to be smaller than the magnon lifetime at temperature… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.06637v1-abstract-full').style.display = 'inline'; document.getElementById('2201.06637v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.06637v1-abstract-full" style="display: none;"> For a wide range of nonclassical magnonic states that have been proposed and demonstrated recently, a new time scale besides the magnon lifetime - the magnon dephasing time - becomes important, but this time scale is rarely studied. Considering exchange interaction and spin-phonon coupling, we evaluate the pure magnon dephasing time and find it to be smaller than the magnon lifetime at temperatures of a few Kelvins. By examining a magnonic cat state as an example, we show how pure dephasing of magnons destroys and limits the survival of quantum superpositions. Thus it will be critical to perform quantum operations within the pure dephasing time. We further derive the master equation for the density matrix describing such magnonic quantum states taking into account the role of pure dephasing, whose methodology can be generalized to include additional dephasing channels that experiments are likely to encounter in the future. Our findings enable one to design and manipulate robust quantum states of magnons for information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.06637v1-abstract-full').style.display = 'none'; document.getElementById('2201.06637v1-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 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review B 106, L100403 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.05370">arXiv:2201.05370</a> <span> [<a href="https://arxiv.org/pdf/2201.05370">pdf</a>, <a href="https://arxiv.org/ps/2201.05370">ps</a>, <a href="https://arxiv.org/format/2201.05370">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/10.1002/andp.202000154">10.1002/andp.202000154 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spectrum of Single-Photon Scattering in a Strong-Coupling Hybrid Optomechanical System </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S+Y">S. Y. Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+W+Z">W. Z. Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">H. Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.05370v1-abstract-short" style="display: inline;"> We analyze theoretically the single-photon excitation and transmission spectra of a strong-coupling hybrid optomechanics, where a two-level system (TLS) is coupled to the mechanical resonator (MR), generating the Jaynes-Cummings-type polariton doublets. In our model, both the optomichanical coupling and the TLS-MR coupling are strong. In this parameter region, the polaron-assisted excitation and r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.05370v1-abstract-full').style.display = 'inline'; document.getElementById('2201.05370v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.05370v1-abstract-full" style="display: none;"> We analyze theoretically the single-photon excitation and transmission spectra of a strong-coupling hybrid optomechanics, where a two-level system (TLS) is coupled to the mechanical resonator (MR), generating the Jaynes-Cummings-type polariton doublets. In our model, both the optomichanical coupling and the TLS-MR coupling are strong. In this parameter region, the polaron-assisted excitation and reemission processes can strongly affect the single-photon excitation and output spectra of the cavity. We find that the fine structure around each sideband can be used to characterize the TLS-MR and the effective TLS-photon couplings, even at single-quantum level. Thus, the spectrum structures may make it possible to sensitively probe the quantum nature of a macroscopic mechanical element. We further provide a possible approach for tomographic reconstruction of the state of a TLS, utilizing the single-photon transmission spectra. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.05370v1-abstract-full').style.display = 'none'; document.getElementById('2201.05370v1-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 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </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, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Ann. Phys. (Berlin) 2020, 2000154 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.12332">arXiv:2112.12332</a> <span> [<a href="https://arxiv.org/pdf/2112.12332">pdf</a>, <a href="https://arxiv.org/ps/2112.12332">ps</a>, <a href="https://arxiv.org/format/2112.12332">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.106.033703">10.1103/PhysRevA.106.033703 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Two-mode light states before and after delocalized single-photon addition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lan%2C+B">Bo Lan</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hong-chun Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xue-xiang Xu</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="2112.12332v3-abstract-short" style="display: inline;"> We studied the effect of delocalized single-photon addition (DPA) on two input modes containing four cases: two independent coherent states (CSs), two independent thermal states (TSs), two independent single-mode squeezed vacuums (SVs), and an entangled two-mode squeezed vacuum (TMSV). In essence, four types of new non-Gaussian entangled light states are generated. We studied three different resou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.12332v3-abstract-full').style.display = 'inline'; document.getElementById('2112.12332v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.12332v3-abstract-full" style="display: none;"> We studied the effect of delocalized single-photon addition (DPA) on two input modes containing four cases: two independent coherent states (CSs), two independent thermal states (TSs), two independent single-mode squeezed vacuums (SVs), and an entangled two-mode squeezed vacuum (TMSV). In essence, four types of new non-Gaussian entangled light states are generated. We studied three different resources (including entanglement, discorrelation and Wigner negativity) for each two-mode light state. The output states after DPA are entangled, with more parameters and complex structures, characterizing more Wigner negativity or even discorrelation. In contrast, the CSs case is the most tunable protocol, because its negativity under partial transposition, discorrelation, and Wigner logarithmic negativity are more sensitive to superposition phase than those in TSs, SVs and TMSV cases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.12332v3-abstract-full').style.display = 'none'; document.getElementById('2112.12332v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A.106, 033703 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.14241">arXiv:2111.14241</a> <span> [<a href="https://arxiv.org/pdf/2111.14241">pdf</a>, <a href="https://arxiv.org/format/2111.14241">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1016/j.physrep.2022.03.002">10.1016/j.physrep.2022.03.002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum magnonics: when magnon spintronics meets quantum information science </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">H. Y. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yunshan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Kamra%2C+A">Akashdeep Kamra</a>, <a href="/search/quant-ph?searchtype=author&query=Duine%2C+R+A">Rembert A. Duine</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+P">Peng Yan</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="2111.14241v2-abstract-short" style="display: inline;"> Spintronics and quantum information science are two promising candidates for innovating information processing technologies. The combination of these two fields enables us to build solid-state platforms for studying quantum phenomena and for realizing multi-functional quantum tasks. For a long time, however, the intersection of these two fields was limited. This situation has changed significantly… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.14241v2-abstract-full').style.display = 'inline'; document.getElementById('2111.14241v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.14241v2-abstract-full" style="display: none;"> Spintronics and quantum information science are two promising candidates for innovating information processing technologies. The combination of these two fields enables us to build solid-state platforms for studying quantum phenomena and for realizing multi-functional quantum tasks. For a long time, however, the intersection of these two fields was limited. This situation has changed significantly over the last few years because of the remarkable progress in coding and processing information using magnons. On the other hand, significant advances in understanding the entanglement of quasi-particles and in designing high-quality qubits and photonic cavities for quantum information processing provide physical platforms to integrate magnons with quantum systems. From these endeavours, the highly interdisciplinary field of quantum magnonics emerges, which combines spintronics, quantum optics and quantum information science.Here, we give an overview of the recent developments concerning the quantum states of magnons and their hybridization with mature quantum platforms. First, we review the basic concepts of magnons and quantum entanglement and discuss the generation and manipulation of quantum states of magnons, such as single-magnon states, squeezed states and quantum many-body states including Bose-Einstein condensation and the resulting spin superfluidity. We discuss how magnonic systems can be integrated and entangled with quantum platforms including cavity photons, superconducting qubits, nitrogen-vacancy centers, and phonons for coherent information transfer and collaborative information processing. The implications of these hybrid quantum systems for non-Hermitian physics and parity-time symmetry are highlighted, together with applications in quantum memories and high-precision measurements. Finally, we present an outlook on the opportunities in quantum magnonics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.14241v2-abstract-full').style.display = 'none'; document.getElementById('2111.14241v2-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 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">93 pages, 35 figures, Physics Reports (in press)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physics Reports 965, 1-74 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.12279">arXiv:2111.12279</a> <span> [<a href="https://arxiv.org/pdf/2111.12279">pdf</a>, <a href="https://arxiv.org/format/2111.12279">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/10.1002/qute.202100080">10.1002/qute.202100080 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal Scheme for Quantum Metrology </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jing Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+M">Mao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Lingna Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2111.12279v1-abstract-short" style="display: inline;"> Quantum metrology can achieve far better precision than classical metrology, and is one of the most important applications of quantum technologies in the real world. To attain the highest precision promised by quantum metrology, all steps of the schemes need to be optimized, which include the state preparation, parametrization, and measurement. Here the recent progresses on the optimization of the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12279v1-abstract-full').style.display = 'inline'; document.getElementById('2111.12279v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.12279v1-abstract-full" style="display: none;"> Quantum metrology can achieve far better precision than classical metrology, and is one of the most important applications of quantum technologies in the real world. To attain the highest precision promised by quantum metrology, all steps of the schemes need to be optimized, which include the state preparation, parametrization, and measurement. Here the recent progresses on the optimization of these steps, which are essential for the identification and achievement of the ultimate precision limit in quantum metrology, are reviewed. It is hoped this provides a useful reference for the researchers in quantum metrology and related fields. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12279v1-abstract-full').style.display = 'none'; document.getElementById('2111.12279v1-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 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Adv. Quantum Technol. 5, 2100080 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.09045">arXiv:2110.09045</a> <span> [<a href="https://arxiv.org/pdf/2110.09045">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0078426">10.1063/5.0078426 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Burst Eddy Current Testing with a Diamond Magnetometry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+C">Chang Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jixing Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Heng Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Bian%2C+G">Guodong Bian</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+P">Pengcheng Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Minxin 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="2110.09045v2-abstract-short" style="display: inline;"> In this work, a burst eddy current testing technique based on the employment of a diamond nitrogen vacancy (NV) center magnetometer with the Hahn echo (HE) sequence is demonstrated. With the confocal experiment apparatus, the HE-based NV magnetometer attained a magnetic sensitivity of $4.3 ~ \mathrm{nT} / \sqrt{\mathrm{Hz}}$ and a volume-normalized sensitivity of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.09045v2-abstract-full').style.display = 'inline'; document.getElementById('2110.09045v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.09045v2-abstract-full" style="display: none;"> In this work, a burst eddy current testing technique based on the employment of a diamond nitrogen vacancy (NV) center magnetometer with the Hahn echo (HE) sequence is demonstrated. With the confocal experiment apparatus, the HE-based NV magnetometer attained a magnetic sensitivity of $4.3 ~ \mathrm{nT} / \sqrt{\mathrm{Hz}}$ and a volume-normalized sensitivity of $3.6 ~ \mathrm{pT} / \sqrt{\mathrm{Hz} \cdot \mathrm{mm}^{-3}}$, which are 5 times better than the already existing method under the same conditions. Based on the proposed magnetometer configuration, a burst eddy current (BEC) testing prototype achieves a minimum detectable sample smaller than ${300~渭 \mathrm{m}}$ and measurement accuracy of $9.85~\mathrm渭 \mathrm{m}$., which is employed to image different metallic specimens and detect the layered internal structures. Since our prototype comprises superb high sensitivity, it exhibits various potential applications in the fields of deformation monitoring, security screening, and quality control. Moreover, its biocompatibility and promising nanoscale resolution paves the way for electromagnetic testing in the fields of biomaterials. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.09045v2-abstract-full').style.display = 'none'; document.getElementById('2110.09045v2-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.05967">arXiv:2110.05967</a> <span> [<a href="https://arxiv.org/pdf/2110.05967">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of anyonic Bloch oscillations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weixuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiteng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Di%2C+F">Fengxiao Di</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+N">Na Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+X">Xingen Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+H">Houjun Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xiangdong 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="2110.05967v2-abstract-short" style="display: inline;"> Bloch oscillations are exotic phenomena describing the periodic motion of a wave packet subjected to the external force in a lattice, where the system possessing single- or multipleparticles could exhibit distinct oscillation behaviors. In particular, it has been pointed out that quantum statistics could dramatically affected the Bloch oscillation even in the absence of particle interactions, wher… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.05967v2-abstract-full').style.display = 'inline'; document.getElementById('2110.05967v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.05967v2-abstract-full" style="display: none;"> Bloch oscillations are exotic phenomena describing the periodic motion of a wave packet subjected to the external force in a lattice, where the system possessing single- or multipleparticles could exhibit distinct oscillation behaviors. In particular, it has been pointed out that quantum statistics could dramatically affected the Bloch oscillation even in the absence of particle interactions, where the oscillation frequency of two pseudofermions with the anyonic statistical angle being pi becomes half of that for two bosons. However, these statisticdependent Bloch oscillations have never been observed in experiments up to now. Here, we report the first experimental simulation of anyonic Bloch oscillations using electric circuits. By mapping eigenstates of two anyons to modes of designed circuit simulators, the Bloch oscillation of two bosons and two pseudofermions are verified by measuring the voltage dynamics. It is found that the oscillation period in the two-boson simulator is almost twice of that in the two-pseudofermion simulator, which is consistent with the theoretical prediction. Our proposal provides a flexible platform to investigate and visualize many interesting phenomena related to particle statistics, and could have potential applications in the field of the novelty signal control. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.05967v2-abstract-full').style.display = 'none'; document.getElementById('2110.05967v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">35 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/2110.04524">arXiv:2110.04524</a> <span> [<a href="https://arxiv.org/pdf/2110.04524">pdf</a>, <a href="https://arxiv.org/ps/2110.04524">ps</a>, <a href="https://arxiv.org/format/2110.04524">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> The generalized Hamilton principle and non-Hermitian quantum theory </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+X">Xiang-Yao Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+B">Ben-Shan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+M">Meng Han</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+M">Ming-Li Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Heng-Mei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hong-Chun Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Si-Qi 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="2110.04524v1-abstract-short" style="display: inline;"> The Hamilton principle is a variation principle describing the isolated and conservative systems, its Lagrange function is the difference between kinetic energy and potential energy. By Feynman path integration, we can obtain the Hermitian quantum theory, i.e., the standard Schrodinger equation. In this paper, we have given the generalized Hamilton principle, which can describe the open system (ma… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.04524v1-abstract-full').style.display = 'inline'; document.getElementById('2110.04524v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.04524v1-abstract-full" style="display: none;"> The Hamilton principle is a variation principle describing the isolated and conservative systems, its Lagrange function is the difference between kinetic energy and potential energy. By Feynman path integration, we can obtain the Hermitian quantum theory, i.e., the standard Schrodinger equation. In this paper, we have given the generalized Hamilton principle, which can describe the open system (mass or energy exchange systems) and nonconservative force systems or dissipative systems. On this basis, we have given the generalized Lagrange function, it has to do with the kinetic energy, potential energy and the work of nonconservative forces to do. With the Feynman path integration, we have given the non-Hermitian quantum theory of the nonconservative force systems. Otherwise, we have given the generalized Hamiltonian function for the particle exchanging heat with the outside world, which is the sum of kinetic energy, potential energy and thermal energy, and further given the equation of quantum thermodynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.04524v1-abstract-full').style.display = 'none'; document.getElementById('2110.04524v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.01844">arXiv:2110.01844</a> <span> [<a href="https://arxiv.org/pdf/2110.01844">pdf</a>, <a href="https://arxiv.org/format/2110.01844">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/2058-9565/ac5d7e">10.1088/2058-9565/ac5d7e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Global Heisenberg scaling in noisy and practical phase estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hayashi%2C+M">Masahito Hayashi</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zi-Wen Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.01844v1-abstract-short" style="display: inline;"> Heisenberg scaling characterizes the ultimate precision of parameter estimation enabled by quantum mechanics, which represents an important quantum advantage of both theoretical and technological interest. Here, we study the attainability of strong, global notions of Heisenberg scaling in the fundamental problem of phase estimation, from a practical standpoint. A main message of this work is an as… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.01844v1-abstract-full').style.display = 'inline'; document.getElementById('2110.01844v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.01844v1-abstract-full" style="display: none;"> Heisenberg scaling characterizes the ultimate precision of parameter estimation enabled by quantum mechanics, which represents an important quantum advantage of both theoretical and technological interest. Here, we study the attainability of strong, global notions of Heisenberg scaling in the fundamental problem of phase estimation, from a practical standpoint. A main message of this work is an asymptotic noise "threshold" for global Heisenberg scaling. We first demonstrate that Heisenberg scaling is fragile to noises in the sense that it cannot be achieved in the presence of phase damping noise with strength above a stringent scaling in the system size. Nevertheless, we show that when the noise does not exceed this threshold, the global Heisenberg scaling in terms of limiting distribution (which we highlight as a practically important figure of merit) as well as average error can indeed be achieved. Furthermore, we provide a practical adaptive protocol using one qubit only, which achieves global Heisenberg scaling in terms of limiting distribution under such noise. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.01844v1-abstract-full').style.display = 'none'; document.getElementById('2110.01844v1-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 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Science and Technology, vol. 7, no. 2, 025030 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.08334">arXiv:2109.08334</a> <span> [<a href="https://arxiv.org/pdf/2109.08334">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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"> Observation of non-Hermitian many-body skin effects in Hilbert space </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weixuan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Di%2C+F">Fengxiao Di</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Haiteng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+X">Xingen Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=He1%2C+L">Lu He1</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+H">Houjun Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xiangdong 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="2109.08334v1-abstract-short" style="display: inline;"> Non-Hermiticity greatly expands existing physical laws beyond the Hermitian framework, revealing various novel phenomena with unique properties. Up to now, most exotic nonHermitian effects, such as exceptional points and non-Hermitian skin effects, are discovered in single-particle systems. The interplay between non-Hermitian and manybody correlation is expected to be a more fascinating but much l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.08334v1-abstract-full').style.display = 'inline'; document.getElementById('2109.08334v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.08334v1-abstract-full" style="display: none;"> Non-Hermiticity greatly expands existing physical laws beyond the Hermitian framework, revealing various novel phenomena with unique properties. Up to now, most exotic nonHermitian effects, such as exceptional points and non-Hermitian skin effects, are discovered in single-particle systems. The interplay between non-Hermitian and manybody correlation is expected to be a more fascinating but much less explored area. Due to the complexity of the problem, current researches in this field mainly stay at the theoretical level. The experimental observation of predicted non-Hermitian manybody phases is still a great challenging. Here, we report the first experimental simulation of strongly correlated non-Hermitian many-body system, and reveal a new type of nonHermitian many-body skin states toward effective boundaries in Hilbert space. Such an interaction-induced non-Hermitian many-body skin effect represents the aggregation of bosonic clusters with non-identical occupations in the periodic lattice. In particular, by mapping eigen-states of three correlated bosons to modes of the designed threedimensional electric circuit, non-Hermitian many-body skin effects in Hilbert space is verified by measuring the spatial impedance response. Our finding not only discloses a new physical effect in the non-Hermitian many-body system, but also suggests a flexible platform to further investigate other non-Hermitian correlated phases in experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.08334v1-abstract-full').style.display = 'none'; document.getElementById('2109.08334v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.05807">arXiv:2109.05807</a> <span> [<a href="https://arxiv.org/pdf/2109.05807">pdf</a>, <a href="https://arxiv.org/format/2109.05807">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.105.062442">10.1103/PhysRevA.105.062442 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Incompatibility measures in multi-parameter quantum estimation under hierarchical quantum measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hongzhen Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Haidong Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.05807v3-abstract-short" style="display: inline;"> The incompatibility of the measurements constraints the achievable precisions in multi-parameter quantum estimation. Understanding the tradeoff induced by such incompatibility is a central topic in quantum metrology. Here we provide an approach to study the incompatibility under general $p$-local measurements, which are the measurements that can be performed collectively on at most $p$ copies of q… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05807v3-abstract-full').style.display = 'inline'; document.getElementById('2109.05807v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.05807v3-abstract-full" style="display: none;"> The incompatibility of the measurements constraints the achievable precisions in multi-parameter quantum estimation. Understanding the tradeoff induced by such incompatibility is a central topic in quantum metrology. Here we provide an approach to study the incompatibility under general $p$-local measurements, which are the measurements that can be performed collectively on at most $p$ copies of quantum states. We demonstrate the power of the approach by presenting a hierarchy of analytical bounds on the tradeoff among the precision limits of different parameters. These bounds lead to a necessary condition for the saturation of the quantum Cram茅r-Rao bound under $p$-local measurements, which recovers the partial commutative condition at p=1 and the weak commutative condition at $p=\infty$. As a further demonstration of the power of the framework, we present another set of tradeoff relations with the right logarithmic operators(RLD). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.05807v3-abstract-full').style.display = 'none'; document.getElementById('2109.05807v3-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 5 figures, with improved bounds</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 105, 062442 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.11342">arXiv:2107.11342</a> <span> [<a href="https://arxiv.org/pdf/2107.11342">pdf</a>, <a href="https://arxiv.org/format/2107.11342">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Classical Physics">physics.class-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevE.105.L022101">10.1103/PhysRevE.105.L022101 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimizing Thermodynamic Cycles with Two Finite-Sized Reservoirs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yu-Han Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C+P">C. P. Sun</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.11342v3-abstract-short" style="display: inline;"> We study the non-equilibrium thermodynamics of a heat engine operating between two finite-sized reservoirs with well-defined temperatures. Within the linear response regime, it is found that the uniform temperature of the two reservoirs at final time $蟿$ is bounded from below by the entropy production $蟽_{\mathrm{min}}\propto1/蟿$. We discover a general power-efficiency trade-off depending on the r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.11342v3-abstract-full').style.display = 'inline'; document.getElementById('2107.11342v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.11342v3-abstract-full" style="display: none;"> We study the non-equilibrium thermodynamics of a heat engine operating between two finite-sized reservoirs with well-defined temperatures. Within the linear response regime, it is found that the uniform temperature of the two reservoirs at final time $蟿$ is bounded from below by the entropy production $蟽_{\mathrm{min}}\propto1/蟿$. We discover a general power-efficiency trade-off depending on the ratio of heat capacities ($纬$) of the reservoirs for the engine. And a universal efficiency at maximum average power of the engine for arbitrary $纬$ is obtained. For practical purposes, the operation protocol of an ideal gas heat engine to achieve the optimal performance associated with $蟽_{\mathrm{min}}$ is demonstrated. Our findings can be used to develop an general optimization scenario for thermodynamic cycles with finite-sized reservoirs in real-world circumstances. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.11342v3-abstract-full').style.display = 'none'; document.getElementById('2107.11342v3-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 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures. The discussion on optimal operation of the heat engine is added. 8 pages and 1 figure of the Supplemental Material. Comments are wellcome</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. E 105, L022101 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.05580">arXiv:2105.05580</a> <span> [<a href="https://arxiv.org/pdf/2105.05580">pdf</a>, <a href="https://arxiv.org/format/2105.05580">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-021-22887-6">10.1038/s41467-021-22887-6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A generalised multipath delayed-choice experiment on a large-scale quantum nanophotonic chip </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiaojiong Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+Y">Yaohao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shuheng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Pramanik%2C+T">Tanumoy Pramanik</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+J">Jun Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Bao%2C+J">Jueming Bao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhai%2C+C">Chonghao Zhai</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+T">Tianxiang Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Huihong Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+J">Jiajie Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Fei%2C+S">Shao-Ming Fei</a>, <a href="/search/quant-ph?searchtype=author&query=Huber%2C+M">Marcus Huber</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+B">Bo Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zhihua Li</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Q">Qiongyi He</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+Q">Qihuang Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jianwei Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.05580v1-abstract-short" style="display: inline;"> Famous double-slit or double-path experiments, implemented in a Young's or Mach-Zehnder interferometer, have confirmed the dual nature of quantum matter, When a stream of photons, neutrons, atoms, or molecules, passes through two slits, either wave-like interference fringes build up on a screen, or particle-like which-path distribution can be ascertained. These quantum objects exhibit both wave an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.05580v1-abstract-full').style.display = 'inline'; document.getElementById('2105.05580v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.05580v1-abstract-full" style="display: none;"> Famous double-slit or double-path experiments, implemented in a Young's or Mach-Zehnder interferometer, have confirmed the dual nature of quantum matter, When a stream of photons, neutrons, atoms, or molecules, passes through two slits, either wave-like interference fringes build up on a screen, or particle-like which-path distribution can be ascertained. These quantum objects exhibit both wave and particle properties but exclusively, depending on the way they are measured. In an equivalent Mach-Zehnder configuration, the object displays either wave or particle nature in the presence or absence of a beamsplitter, respectively, that represents the choice of which-measurement. Wheeler further proposed a gedanken experiment, in which the choice of which-measurement is delayed, i.e. determined after the object has already entered the interferometer, so as to exclude the possibility of predicting which-measurement it will confront. The delayed-choice experiments have enabled significant demonstrations of genuine two-path duality of different quantum objects. Recently, a quantum controlled version of delayed-choice was proposed by Ionicioiu and Terno, by introducing a quantum-controlled beamsplitter that is in a coherent superposition of presence and absence. It represents a controllable experiment platform that can not only reveal wave and particle characters, but also their superposition. Moreover, a quantitative description of two-slit duality relation was initialized in Wootters and Zurek's seminal work and formalized by Greenberger,et. al. as D2+V2<=1, where D is the distinguishability of whichpath information, and V is the contrast visibility of interference. In this regard, getting which-path information exclusively reduces the interference visibility, and vice versa. This double-path duality relation has been tested in pioneer experiments and recently in delayed-choice measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.05580v1-abstract-full').style.display = 'none'; document.getElementById('2105.05580v1-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 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Commun. 12, 2712 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.05436">arXiv:2105.05436</a> <span> [<a href="https://arxiv.org/pdf/2105.05436">pdf</a>, <a href="https://arxiv.org/ps/2105.05436">ps</a>, <a href="https://arxiv.org/format/2105.05436">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Controllable double optical bistability via photon and phonon interaction in a hybrid optomechanical system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cheng Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yong He</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">Chang-Ying Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+X">Xiao-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Heng-Mei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H">Hong-Chun Yuan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.05436v1-abstract-short" style="display: inline;"> The optical bistability have been studied theoretically in a multi-mode optomechanical system with two mechanical oscillators independently coupled to two cavities in addition to direct tunnel coupling between cavities. It is proved that the bistable behavior of mean intracavity photon number in the right cavity can be tuned by adjusting the strength of the pump laser beam driving the left cavity.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.05436v1-abstract-full').style.display = 'inline'; document.getElementById('2105.05436v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.05436v1-abstract-full" style="display: none;"> The optical bistability have been studied theoretically in a multi-mode optomechanical system with two mechanical oscillators independently coupled to two cavities in addition to direct tunnel coupling between cavities. It is proved that the bistable behavior of mean intracavity photon number in the right cavity can be tuned by adjusting the strength of the pump laser beam driving the left cavity. And the mean intracavity photon number is relatively larger in the red sideband regime than that in the blue sideband regime. Moreover, we have shown that the double optical bistability of intracavity photon in the right cavity and the two steady-state positions of mechanical resonators can be observed when the control field power is increased to a critical value. Besides, the critical values for observing bistability and double bistability can be tuned by adjusting the coupling coefficient between two cavities and the coupling rates between cavities mode and mechanical mode. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.05436v1-abstract-full').style.display = 'none'; document.getElementById('2105.05436v1-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 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.15899">arXiv:2103.15899</a> <span> [<a href="https://arxiv.org/pdf/2103.15899">pdf</a>, <a href="https://arxiv.org/format/2103.15899">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.16.024047">10.1103/PhysRevApplied.16.024047 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electrically switchable entanglement channel in van der Waals magnets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+H+Y">H. Y. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Kamra%2C+A">Akashdeep Kamra</a>, <a href="/search/quant-ph?searchtype=author&query=Hartmann%2C+D+M+F">Dion M. F. Hartmann</a>, <a href="/search/quant-ph?searchtype=author&query=Duine%2C+R+A">Rembert A. Duine</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="2103.15899v1-abstract-short" style="display: inline;"> Two dimensional layered van der Waals (vdW) magnets have demonstrated their potential to study both fundamental and applied physics due to their remarkable electronic properties. However, the connection of vdW magnets to spintronics as well as quantum information science is not clear. In particular, it remains elusive whether there are novel magnetic phenomena only belonging to vdW magnets, but ab… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.15899v1-abstract-full').style.display = 'inline'; document.getElementById('2103.15899v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.15899v1-abstract-full" style="display: none;"> Two dimensional layered van der Waals (vdW) magnets have demonstrated their potential to study both fundamental and applied physics due to their remarkable electronic properties. However, the connection of vdW magnets to spintronics as well as quantum information science is not clear. In particular, it remains elusive whether there are novel magnetic phenomena only belonging to vdW magnets, but absent in the widely studied crystalline magnets. Here we consider the quantum correlations of magnons in a layered vdW magnet and identify an entanglement channel of magnons across the magnetic layers, which can be effectively tuned and even deterministically switched on and off by both magnetic and electric means. This is a unique feature of vdW magnets in which the underlying physics is well understood in terms of the competing roles of exchange and anisotropy fields that contribute to the magnon excitation. Furthermore, we show that such a tunable entanglement channel can mediate the electrically controllable entanglement of two distant qubits, which also provides a protocol to indirectly measure the entanglement of magnons. Our findings provide a novel avenue to electrically manipulate the qubits and further open up new opportunities to utilize vdW magnets for quantum information science. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.15899v1-abstract-full').style.display = 'none'; document.getElementById('2103.15899v1-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 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 16, 024047 (2021) </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Yuan%2C+H&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> 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