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class="pagination-link " aria-label="Page 5" aria-current="page">5 </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/2412.02180">arXiv:2412.02180</a> <span> [<a href="https://arxiv.org/pdf/2412.02180">pdf</a>, <a href="https://arxiv.org/format/2412.02180">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div 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.22.054040">10.1103/PhysRevApplied.22.054040 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optical losses as a function of beam position on the mirrors in a 285-m suspended Fabry-Perot cavity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Y">Y. Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Vardaro%2C+M">M. Vardaro</a>, <a href="/search/quant-ph?searchtype=author&query=Capocasa%2C+E">E. Capocasa</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+J">J. Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Y. Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Lequime%2C+M">M. Lequime</a>, <a href="/search/quant-ph?searchtype=author&query=Barsuglia%2C+M">M. Barsuglia</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="2412.02180v1-abstract-short" style="display: inline;"> Reducing optical losses is crucial for reducing quantum noise in gravitational-wave detectors. Losses are the main source of degradation of the squeezed vacuum. Frequency dependent squeezing obtained via a filter cavity is currently used to reduce quantum noise in the whole detector bandwidth. Such filter cavities are required to have high finesse in order to produce the optimal squeezing angle ro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.02180v1-abstract-full').style.display = 'inline'; document.getElementById('2412.02180v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.02180v1-abstract-full" style="display: none;"> Reducing optical losses is crucial for reducing quantum noise in gravitational-wave detectors. Losses are the main source of degradation of the squeezed vacuum. Frequency dependent squeezing obtained via a filter cavity is currently used to reduce quantum noise in the whole detector bandwidth. Such filter cavities are required to have high finesse in order to produce the optimal squeezing angle rotation and the presence of losses is particularly detrimental for the squeezed beam, as it does multiple round trip within the cavity. Characterising such losses is crucial to assess the quantum noise reduction achievable. In this paper we present an in-situ measurement of the optical losses, done for different positions of the beam on the mirrors of the Virgo filter cavity. We implemented an automatic system to map the losses with respect to the beam position on the mirrors finding that optical losses depend clearly on the beam hitting position on input mirror, varying from 42 ppm to 87 ppm, while they are much more uniform when we scan the end mirror (53 ppm to 61 ppm). We repeated the measurements on several days, finding a statistical error smaller than 4 ppm. The lowest measured losses are not much different with respect to those estimated from individual mirror characterisation performed before the installation (30.3 - 39.3 ppm). This means that no major loss mechanism has been neglected in the estimation presented here. The larger discrepancy found for some beam positions is likely to be due to contamination. In addition to a thorough characterisation of the losses, the methodology described in this paper allowed to find an optimal cavity axis position for which the cavity round trip losses are among the lowest ever measured. This work can contribute to achieve the very challenging losses goals for the optical cavities of the future gravitational-wave detectors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.02180v1-abstract-full').style.display = 'none'; document.getElementById('2412.02180v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This work has been accepted for publication in Physical Review Applied. The final version is available at https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.22.054040</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 22, 054040, 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.17020">arXiv:2411.17020</a> <span> [<a href="https://arxiv.org/pdf/2411.17020">pdf</a>, <a href="https://arxiv.org/format/2411.17020">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> </div> </div> <p class="title is-5 mathjax"> Tower of Structured Excited States from Measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuxuan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Ashida%2C+Y">Yuto Ashida</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="2411.17020v1-abstract-short" style="display: inline;"> Preparing highly entangled quantum states is a key challenge in quantum metrology and quantum information science. Measurements, especially those of global observables, offer a simple and efficient way to generate entanglement between subsystems when they are measured as a whole. We introduce a log-depth protocol leveraging quantum phase estimation to measure a global observable, such as total mag… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.17020v1-abstract-full').style.display = 'inline'; document.getElementById('2411.17020v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.17020v1-abstract-full" style="display: none;"> Preparing highly entangled quantum states is a key challenge in quantum metrology and quantum information science. Measurements, especially those of global observables, offer a simple and efficient way to generate entanglement between subsystems when they are measured as a whole. We introduce a log-depth protocol leveraging quantum phase estimation to measure a global observable, such as total magnetization and momentum. We demonstrate its capability to prepare towers of structured excited states that are useful in quantum metrology; examples include quantum many-body scars in various models, including the Affleck-Kennedy-Lieb-Tasaki (AKLT) model, the constrained domain-wall model, and the spin-$\frac{1}{2}$ and spin-$1$ XX chains. The same method is also applicable to preparing the Dicke states of high weight. In addition, we propose a protocol for momentum measurement that avoids disturbing the system, facilitating the preparation of states beyond the above construction, such as the Arovas $A$ state of the AKLT Hamiltonian. Our results expand the utility of measurement-based approaches to accessing highly entangled states in quantum many-body systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.17020v1-abstract-full').style.display = 'none'; document.getElementById('2411.17020v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 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">15 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/2410.13734">arXiv:2410.13734</a> <span> [<a href="https://arxiv.org/pdf/2410.13734">pdf</a>, <a href="https://arxiv.org/format/2410.13734">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Strong-to-weak spontaneous symmetry breaking meets average symmetry-protected topological order </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo 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="2410.13734v1-abstract-short" style="display: inline;"> Recent studies have unveiled new possibilities for discovering intrinsic quantum phases that are unique to open systems, including phases with average symmetry-protected topological (ASPT) order and strong-to-weak spontaneous symmetry breaking (SWSSB) order in systems with global symmetry. In this work, we propose a new class of phases, termed the double ASPT phase, which emerges from a nontrivial… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.13734v1-abstract-full').style.display = 'inline'; document.getElementById('2410.13734v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.13734v1-abstract-full" style="display: none;"> Recent studies have unveiled new possibilities for discovering intrinsic quantum phases that are unique to open systems, including phases with average symmetry-protected topological (ASPT) order and strong-to-weak spontaneous symmetry breaking (SWSSB) order in systems with global symmetry. In this work, we propose a new class of phases, termed the double ASPT phase, which emerges from a nontrivial extension of these two orders. This new phase is absent from prior studies and cannot exist in conventional closed systems. Using the recently developed imaginary-Lindbladian formalism, we explore the phase diagram of a one-dimensional open system with $\mathbb{Z}_2^蟽\times \mathbb{Z}_2^蟿$ symmetry. We identify universal critical behaviors along each critical line and observe the emergence of an intermediate phase that completely breaks the $\mathbb{Z}_2^蟽$ symmetry, leading to the formation of two triple points in the phase diagram. These two triple points are topologically distinct and connected by a domain-wall decoration duality map. Our results promote the establishment of a complete classification for quantum phases in open systems with various symmetry conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.13734v1-abstract-full').style.display = 'none'; document.getElementById('2410.13734v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 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">10 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.13176">arXiv:2410.13176</a> <span> [<a href="https://arxiv.org/pdf/2410.13176">pdf</a>, <a href="https://arxiv.org/ps/2410.13176">ps</a>, <a href="https://arxiv.org/format/2410.13176">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-classical correspondence of non-Hermitian spin-orbit coupled bosonic junction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yan%2C+X">Xin Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hongzheng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+C">Changwei Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+B">Baiyuan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+X">Xiaobing Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+J">Jinpeng Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Z">Zhao-Yun Zeng</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="2410.13176v2-abstract-short" style="display: inline;"> We investigate the classical-quantum correspondence of non-Hermitian Spin-orbit (SO)-coupled bosonic junctions, where an effective decay term is introduced in one of the two wells. Starting from the normalized two-point functions, we analytically demonstrate that the mean-field system has a classical Hamiltonian structure, and we successfully derive a non-Hermitian discrete nonlinear Schr枚dinger (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.13176v2-abstract-full').style.display = 'inline'; document.getElementById('2410.13176v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.13176v2-abstract-full" style="display: none;"> We investigate the classical-quantum correspondence of non-Hermitian Spin-orbit (SO)-coupled bosonic junctions, where an effective decay term is introduced in one of the two wells. Starting from the normalized two-point functions, we analytically demonstrate that the mean-field system has a classical Hamiltonian structure, and we successfully derive a non-Hermitian discrete nonlinear Schr枚dinger (Gross-Pitaevskii) equation. We discover that near the symmetry-breaking phase transition point, the correspondence between classical (mean-field) and quantum dynamics is more likely to break down. When the effective spin-orbit coupling (SOC) strength assumes half-integer values, atomic self-trapping in the non-lossy well definitely occurs, regardless of the system parameters, and the quantum dynamics is insensitive to the number of particles. Additionally, we reveal that in both the mean-field and many-particle models, the SOC effects can greatly promote the synchronous periodic oscillations between the spin-up and spin-down components, and this synchronization dynamics is protected by a symmetry mechanism. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.13176v2-abstract-full').style.display = 'none'; document.getElementById('2410.13176v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 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">13 pages, 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.11219">arXiv:2410.11219</a> <span> [<a href="https://arxiv.org/pdf/2410.11219">pdf</a>, <a href="https://arxiv.org/ps/2410.11219">ps</a>, <a href="https://arxiv.org/format/2410.11219">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"> Relationship between average correlation and quantum steering for arbitrary two-qubit states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+y">youneng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiangjun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+h">huping Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Tian%2C+q">qinglong Tian</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="2410.11219v1-abstract-short" style="display: inline;"> Quantum nonlocality and nonclassicality are two remarkable characteristics of quantum theory, and offer quantum advantages in some quantum information processing. Motivated by recent work on the interplay between nonclassicality quantified by average correlation [Tschaffon et al., Phys. Rev. Res. 5,023063 (2023)] and Bell nonlocality, in this paper we aim to establish the relationship between the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.11219v1-abstract-full').style.display = 'inline'; document.getElementById('2410.11219v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.11219v1-abstract-full" style="display: none;"> Quantum nonlocality and nonclassicality are two remarkable characteristics of quantum theory, and offer quantum advantages in some quantum information processing. Motivated by recent work on the interplay between nonclassicality quantified by average correlation [Tschaffon et al., Phys. Rev. Res. 5,023063 (2023)] and Bell nonlocality, in this paper we aim to establish the relationship between the average correlation and the violation of the three-setting linear steering inequality for two-qubit systems. Exact lower and upper bounds of average correlation versus steering are obtained, and the respective states which suffice those bounds are also characterized. For clarity of our presentation, we illustrate these results with examples from well-known classes of two-qubit states. Moreover, the dynamical behavior of these two quantifiers is carefully analyzed under the influence of local unital and nonunital noisy channels. The results suggest that average correlation is closely related to the violation of three-setting linear steering, like its relationship with Bell violation. Particularly, for a given class of states, the hierarchy of nonclassicality-steering-Bell nonlocality is demonstrated. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.11219v1-abstract-full').style.display = 'none'; document.getElementById('2410.11219v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <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">2</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.13517">arXiv:2409.13517</a> <span> [<a href="https://arxiv.org/pdf/2409.13517">pdf</a>, <a href="https://arxiv.org/format/2409.13517">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Networking and Internet Architecture">cs.NI</span> </div> </div> <p class="title is-5 mathjax"> Efficient Entanglement Routing for Satellite-Aerial-Terrestrial Quantum Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+Y">Yanmin Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+L">Lei Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zhu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuanxiong Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.13517v1-abstract-short" style="display: inline;"> In the era of 6G and beyond, space-aerial-terrestrial quantum networks (SATQNs) are shaping the future of the global-scale quantum Internet. This paper investigates the collaboration among satellite, aerial, and terrestrial quantum networks to efficiently transmit high-fidelity quantum entanglements over long distances. We begin with a comprehensive overview of existing satellite-, aerial-, and te… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13517v1-abstract-full').style.display = 'inline'; document.getElementById('2409.13517v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.13517v1-abstract-full" style="display: none;"> In the era of 6G and beyond, space-aerial-terrestrial quantum networks (SATQNs) are shaping the future of the global-scale quantum Internet. This paper investigates the collaboration among satellite, aerial, and terrestrial quantum networks to efficiently transmit high-fidelity quantum entanglements over long distances. We begin with a comprehensive overview of existing satellite-, aerial-, and terrestrial-based quantum networks. Subsequently, we address the entanglement routing problem with the objective of maximizing quantum network throughput by jointly optimizing path selection and entanglement generation rates (PS-EGR). Given that the original problem is formulated as a mixed-integer linear programming (MILP) problem, which is inherently intractable, we propose a Benders' decomposition (BD)-based algorithm to solve the problem efficiently. Numerical results validate the effectiveness of the proposed PS-EGR scheme, offering valuable insights into various optimizable factors within the system. Finally, we discuss the current challenges and propose promising avenues for future research in SATQNs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.13517v1-abstract-full').style.display = 'none'; document.getElementById('2409.13517v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 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/2409.05419">arXiv:2409.05419</a> <span> [<a href="https://arxiv.org/pdf/2409.05419">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="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Super-bunching light with giant high-order correlations and extreme multi-photon events </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qin%2C+C">Chengbing Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuanyuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+Y">Yu Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jiamin Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangdong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Y">Yunrui Song</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xuedong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+S">Shuangping Han</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zihua Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanqiang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+G">Guofeng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+R">Ruiyun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+J">Jianyong Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Z">Zhichun Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xinhui Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+L">Liantuan Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+S">Suotang Jia</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.05419v3-abstract-short" style="display: inline;"> Non-classical light sources emitting bundles of N-photons with strong correlation represent versatile resources of interdisciplinary importance with applications ranging from fundamental tests of quantum mechanics to quantum information processing. Yet, high-order correlations, gN(0),quantifying photon correlation, are still limited to hundreds. Here, we report the generation of a super-bunching l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05419v3-abstract-full').style.display = 'inline'; document.getElementById('2409.05419v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.05419v3-abstract-full" style="display: none;"> Non-classical light sources emitting bundles of N-photons with strong correlation represent versatile resources of interdisciplinary importance with applications ranging from fundamental tests of quantum mechanics to quantum information processing. Yet, high-order correlations, gN(0),quantifying photon correlation, are still limited to hundreds. Here, we report the generation of a super-bunching light source in photonic crystal fiber with g2(0) reaching 5.86*104 and g5(0) up to 2.72*108, through measuring its photon number probability distributions. under giant g2(0) values, the super-bunching light source presents upturned-tail photon distributions and ubiquitous extreme multi-photon events, where 31 photons from a single light pulse at a mean of 1.99*10-4 photons per pulse have been determined. The probability of this extreme event has been enhanced by 10139 folds compared to a coherent laser with Poissonian distribution. By varying the power of the pumping laser, both photon number distributions and corresponding high-order correlations of this light source can be substantially tailored from Poissonian to super-bunching distributions. These phenomena are attributed to the synchronized nonlinear interactions in photonic crystal fibers pumping by bright squeezed light, and the theoretical simulations agree well with the experimental results. Our research showcases the ability to achieve non-classical light sources with giant high-order correlations and extreme multi-photon events, paving the way for high-order correlation imaging, extreme nonlinear optical effects, quantum information processing, and exploring light-matter interactions with multi-photon physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.05419v3-abstract-full').style.display = 'none'; document.getElementById('2409.05419v3-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 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.03217">arXiv:2409.03217</a> <span> [<a href="https://arxiv.org/pdf/2409.03217">pdf</a>, <a href="https://arxiv.org/format/2409.03217">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"> Experimental Catalytic Amplification of Asymmetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Min Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+F">Feng Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xue-Yuan Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yun-Feng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.03217v2-abstract-short" style="display: inline;"> The manipulation and transformation of quantum resources are key parts of quantum mechanics. Among them, asymmetry is one of the most useful operational resources, which is widely used in quantum clocks, quantum metrology, and other tasks. Recent studies have shown that the asymmetry of quantum states can be significantly amplified with the assistance of correlating catalysts which are finite-dime… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.03217v2-abstract-full').style.display = 'inline'; document.getElementById('2409.03217v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.03217v2-abstract-full" style="display: none;"> The manipulation and transformation of quantum resources are key parts of quantum mechanics. Among them, asymmetry is one of the most useful operational resources, which is widely used in quantum clocks, quantum metrology, and other tasks. Recent studies have shown that the asymmetry of quantum states can be significantly amplified with the assistance of correlating catalysts which are finite-dimensional auxiliaries. In the experiment, we perform translationally invariant operations, ensuring that the asymmetric resources of the entire system remain non-increasing, on a composite system composed of a catalytic system and a quantum system. The experimental results demonstrate an asymmetry amplification of 0.0172\pm0.0022 in the system following the catalytic process. Our work showcases the potential of quantum catalytic processes and is expected to inspire further research in the field of quantum resource theories. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.03217v2-abstract-full').style.display = 'none'; document.getElementById('2409.03217v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 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">17pages,7figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.09083">arXiv:2408.09083</a> <span> [<a href="https://arxiv.org/pdf/2408.09083">pdf</a>, <a href="https://arxiv.org/format/2408.09083">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"> Imaginary Hamiltonian variational ansatz for combinatorial optimization problems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chai%2C+Y">Yahui Chai</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+X">Xu Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yibin Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=T%C3%BCys%C3%BCz%2C+C">Cenk T眉ys眉z</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="2408.09083v1-abstract-short" style="display: inline;"> Obtaining exact solutions to combinatorial optimization problems using classical computing is computationally expensive. The current tenet in the field is that quantum computers can address these problems more efficiently. While promising algorithms require fault-tolerant quantum hardware, variational algorithms have emerged as viable candidates for near-term devices. The success of these algorith… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09083v1-abstract-full').style.display = 'inline'; document.getElementById('2408.09083v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.09083v1-abstract-full" style="display: none;"> Obtaining exact solutions to combinatorial optimization problems using classical computing is computationally expensive. The current tenet in the field is that quantum computers can address these problems more efficiently. While promising algorithms require fault-tolerant quantum hardware, variational algorithms have emerged as viable candidates for near-term devices. The success of these algorithms hinges on multiple factors, with the design of the ansatz having the utmost importance. It is known that popular approaches such as quantum approximate optimization algorithm (QAOA) and quantum annealing suffer from adiabatic bottlenecks, that lead to either larger circuit depth or evolution time. On the other hand, the evolution time of imaginary time evolution is bounded by the inverse energy gap of the Hamiltonian, which is constant for most non-critical physical systems. In this work, we propose imaginary Hamiltonian variational ansatz ($i$HVA) inspired by quantum imaginary time evolution to solve the MaxCut problem. We introduce a tree arrangement of the parametrized quantum gates, enabling the exact solution of arbitrary tree graphs using the one-round $i$HVA. For randomly generated $D$-regular graphs, we numerically demonstrate that the $i$HVA solves the MaxCut problem with a small constant number of rounds and sublinear depth, outperforming QAOA, which requires rounds increasing with the graph size. Furthermore, our ansatz solves MaxCut exactly for graphs with up to 24 nodes and $D \leq 5$, whereas only approximate solutions can be derived by the classical near-optimal Goemans-Williamson algorithm. We validate our simulated results with hardware experiments on a graph with 63 nodes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.09083v1-abstract-full').style.display = 'none'; document.getElementById('2408.09083v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 15 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.03239">arXiv:2408.03239</a> <span> [<a href="https://arxiv.org/pdf/2408.03239">pdf</a>, <a href="https://arxiv.org/format/2408.03239">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> A New Framework for Quantum Phases in Open Systems: Steady State of Imaginary-Time Lindbladian Evolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+K">Ke Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo 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="2408.03239v1-abstract-short" style="display: inline;"> This study delves into the concept of quantum phases in open quantum systems, examining the shortcomings of existing approaches that focus on steady states of Lindbladians and highlighting their limitations in capturing key phase transitions. In contrast to these methods, we introduce the concept of imaginary-time Lindbladian evolution as an alternative framework. This new approach defines gapped… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.03239v1-abstract-full').style.display = 'inline'; document.getElementById('2408.03239v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.03239v1-abstract-full" style="display: none;"> This study delves into the concept of quantum phases in open quantum systems, examining the shortcomings of existing approaches that focus on steady states of Lindbladians and highlighting their limitations in capturing key phase transitions. In contrast to these methods, we introduce the concept of imaginary-time Lindbladian evolution as an alternative framework. This new approach defines gapped quantum phases in open systems through the spectrum properties of the imaginary-Liouville superoperator. We find that, in addition to all pure gapped ground states, the Gibbs state of a stabilizer Hamiltonian at any finite temperature can also be characterized by our scheme, demonstrated through explicit construction. To illustrate the effectiveness of this framework, we apply it to investigate the phase diagram for open systems with $\mathbb{Z}_{2}^蟽 \times \mathbb{Z}_{2}^蟿$ symmetry, including cases with nontrivial average symmetry protected topological order or spontaneous symmetry breaking order. Our findings demonstrate universal properties at quantum criticality, such as nonanalytic behaviors of steady-state observables, divergence of correlation lengths, and closing of the imaginary-Liouville gap. These results advance our understanding of quantum phase transitions in open quantum systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.03239v1-abstract-full').style.display = 'none'; document.getElementById('2408.03239v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.00464">arXiv:2408.00464</a> <span> [<a href="https://arxiv.org/pdf/2408.00464">pdf</a>, <a href="https://arxiv.org/format/2408.00464">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"> Optimally robust shortcuts to population inversion in cat-state qubits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+S">Shao-Wei Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhong-Zheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yue-Ying Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye-Hong Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+Y">Yan Xia</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="2408.00464v1-abstract-short" style="display: inline;"> Cat-state qubits formed by photonic coherent states are a promising candidate for realizing fault-tolerant quantum computing. Such logic qubits have a biased noise channel that the bit-flip error dominates over all the other errors. In this manuscript, we propose an optimally robust protocol using the control method of shortcuts to adiabaticity to realize a nearly perfect population inversion in a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.00464v1-abstract-full').style.display = 'inline'; document.getElementById('2408.00464v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.00464v1-abstract-full" style="display: none;"> Cat-state qubits formed by photonic coherent states are a promising candidate for realizing fault-tolerant quantum computing. Such logic qubits have a biased noise channel that the bit-flip error dominates over all the other errors. In this manuscript, we propose an optimally robust protocol using the control method of shortcuts to adiabaticity to realize a nearly perfect population inversion in a cat-state qubit. We construct a shortcut based on the Lewis-Riesenfeld invariant and examine the stability versus different types of perturbations for the fast and robust population inversion. Numerical simulations demonstrate that the population inversion can be mostly insensitive to systematic errors in our protocol. Even when the parameter imperfection rate for bit-flip control is $20\%$, the final population of the target state can still reach $\geq 99\%$. The optimally robust control provides a feasible method for fault-tolerant and scalable quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.00464v1-abstract-full').style.display = 'none'; document.getElementById('2408.00464v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 8 figures, 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/2407.15629">arXiv:2407.15629</a> <span> [<a href="https://arxiv.org/pdf/2407.15629">pdf</a>, <a href="https://arxiv.org/format/2407.15629">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Lattice">hep-lat</span> </div> </div> <p class="title is-5 mathjax"> Concurrent VQE for Simulating Excited States of the Schwinger Model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yibin Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Angelides%2C+T">Takis Angelides</a>, <a href="/search/quant-ph?searchtype=author&query=Jansen%2C+K">Karl Jansen</a>, <a href="/search/quant-ph?searchtype=author&query=K%C3%BChn%2C+S">Stefan K眉hn</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="2407.15629v1-abstract-short" style="display: inline;"> This work explores the application of the concurrent variational quantum eigensolver (cVQE) for computing excited states of the Schwinger model. By designing suitable ansatz circuits utilizing universal SO(4) or SO(8) qubit gates, we demonstrate how to efficiently obtain the lowest two, four, and eight eigenstates with one, two, and three ancillary qubits for both vanishing and non-vanishing backg… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15629v1-abstract-full').style.display = 'inline'; document.getElementById('2407.15629v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.15629v1-abstract-full" style="display: none;"> This work explores the application of the concurrent variational quantum eigensolver (cVQE) for computing excited states of the Schwinger model. By designing suitable ansatz circuits utilizing universal SO(4) or SO(8) qubit gates, we demonstrate how to efficiently obtain the lowest two, four, and eight eigenstates with one, two, and three ancillary qubits for both vanishing and non-vanishing background electric field cases. Simulating the resulting quantum circuits classically with tensor network techniques, we demonstrate the capability of our approach to compute the two lowest eigenstates of systems with up to $\mathcal{O}(100)$ qubits. Given that our method allows for measuring the low-lying spectrum precisely, we also present a novel technique for estimating the additive mass renormalization of the lattice based on the energy gap. As a proof-of-principle calculation, we prepare the ground and first-excited states with one ancillary and four physical qubits on quantum hardware, demonstrating the practicality of using the cVQE to simulate excited states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.15629v1-abstract-full').style.display = 'none'; document.getElementById('2407.15629v1-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 17 figures, 3 tables, 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/2407.02787">arXiv:2407.02787</a> <span> [<a href="https://arxiv.org/pdf/2407.02787">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> A versatile quantum microwave photonic signal processing platform based on coincidence window selection technique </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinghua Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yifan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+X">Xiao Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Quan%2C+R">Runai Quan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+M">Mingtao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.02787v1-abstract-short" style="display: inline;"> Quantum microwave photonics (QMWP) is an innovative approach that combines energy-time entangled biphoton sources as the optical carrier with time-correlated single-photon detection for high-speed RF signal recovery. This groundbreaking method offers unique advantages such as nonlocal RF signal encoding and robust resistance to dispersion-induced frequency fading. This paper explores the versatili… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02787v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02787v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02787v1-abstract-full" style="display: none;"> Quantum microwave photonics (QMWP) is an innovative approach that combines energy-time entangled biphoton sources as the optical carrier with time-correlated single-photon detection for high-speed RF signal recovery. This groundbreaking method offers unique advantages such as nonlocal RF signal encoding and robust resistance to dispersion-induced frequency fading. This paper explores the versatility of processing the quantum microwave photonic signal by utilizing coincidence window selection on the biphoton coincidence distribution. The demonstration includes finely-tunable RF phase shifting, flexible multi-tap transversal filtering (with up to 15 taps), and photonically implemented RF mixing, leveraging the nonlocal RF mapping characteristic of QMWP. These accomplishments significantly enhance the capability of microwave photonic systems in processing ultra-weak signals, opening up new possibilities for various applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02787v1-abstract-full').style.display = 'none'; document.getElementById('2407.02787v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.02774">arXiv:2407.02774</a> <span> [<a href="https://arxiv.org/pdf/2407.02774">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum microwave photonic mixer with a large spurious-free dynamic range </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinghua Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yifan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xiang%2C+X">Xiao Xiang</a>, <a href="/search/quant-ph?searchtype=author&query=Quan%2C+R">Runai Quan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+M">Mingtao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+R">Ruifang Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+T">Tao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+S">Shougang Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.02774v1-abstract-short" style="display: inline;"> As one of the most fundamental functionalities of microwave photonics, microwave frequency mixing plays an essential role in modern radars and wireless communication systems. However, the commonly utilized intensity modulation in the systems often leads to inadequate spurious-free dynamic range (SFDR) for many sought-after applications. Quantum microwave photonics technique offers a promising solu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02774v1-abstract-full').style.display = 'inline'; document.getElementById('2407.02774v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.02774v1-abstract-full" style="display: none;"> As one of the most fundamental functionalities of microwave photonics, microwave frequency mixing plays an essential role in modern radars and wireless communication systems. However, the commonly utilized intensity modulation in the systems often leads to inadequate spurious-free dynamic range (SFDR) for many sought-after applications. Quantum microwave photonics technique offers a promising solution for improving SFDR in terms of higher-order harmonic distortion. In this paper, we demonstrate two types of quantum microwave photonic mixers based on the configuration of the intensity modulators: cascade-type and parallel-type. Leveraging the nonlocal RF signal encoding capability, both types of quantum microwave photonic mixers not only exhibit the advantage of dual-channel output but also present significant improvement in SFDR. Specifically, the parallel-type quantum microwave photonic mixer achieves a remarkable SFDR value of 113.6 dB.Hz1/2, which is 30 dB better than that of the cascade-type quantum microwave photonic mixer. When compared to the classical microwave photonic mixer, this enhancement reaches a notable 53.6 dB at the expense of 8 dB conversion loss. These results highlight the superiority of quantum microwave photonic mixers in the fields of microwave and millimeter-wave systems. Further applying multi-photon frequency entangled sources as optical carriers, the dual-channel microwave frequency conversion capability endowed by the quantum microwave photonic mixer can be extended to enhance the performance of multiple-paths microwave mixing which is essential for radar net systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.02774v1-abstract-full').style.display = 'none'; document.getElementById('2407.02774v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.02236">arXiv:2406.02236</a> <span> [<a href="https://arxiv.org/pdf/2406.02236">pdf</a>, <a href="https://arxiv.org/format/2406.02236">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"> Demonstration of superior communication through thermodynamically free channels in an optical quantum switch </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tang%2C+H">Hao Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Min Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yun-Feng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.02236v1-abstract-short" style="display: inline;"> The release of causal structure of physical events from a well-defined order to an indefinite one stimulates remarkable enhancements in various quantum information tasks. Some of these advantages, however, are questioned for the ambiguous role of the control system in the quantum switch that is an experimentally realized process with indefinite causal structure. In communications, for example, not… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02236v1-abstract-full').style.display = 'inline'; document.getElementById('2406.02236v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.02236v1-abstract-full" style="display: none;"> The release of causal structure of physical events from a well-defined order to an indefinite one stimulates remarkable enhancements in various quantum information tasks. Some of these advantages, however, are questioned for the ambiguous role of the control system in the quantum switch that is an experimentally realized process with indefinite causal structure. In communications, for example, not only the superposition of alternative causal orders, but also the superposition of alternative trajectories can accelerate information transmissions. Here, we follow the proposal of Liu et al. [Phys. Rev. Lett. 129, 230604 (2022)], and examine the information enhancement effect of indefinite causal orders with the toolkit of thermodynamics in a photonic platform. Specifically, we simulate the thermal interaction between a system qubit and two heat baths embedded in a quantum switch by implementing the corresponding switched thermal channels. Although its action on the system qubit only is thermally free, our results suggest that the quantum switch should be seen as a resource when the control qubit is also considered. Moreover, we characterize the non-Markovian property in this scenario by measuring the information backflows from the heat baths to the system qubit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02236v1-abstract-full').style.display = 'none'; document.getElementById('2406.02236v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.02045">arXiv:2406.02045</a> <span> [<a href="https://arxiv.org/pdf/2406.02045">pdf</a>, <a href="https://arxiv.org/format/2406.02045">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"> Experimental single-photon quantum key distribution surpassing the fundamental coherent-state rate limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+X">Xing Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Likang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yong-Peng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+G">Gao-Qiang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ning%2C+Z">Zhen Ning</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+M">Mo-Chi Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+J">Jun-Yi Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+G">Geng-Yan Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Hui Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yu-Ming He</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</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="2406.02045v1-abstract-short" style="display: inline;"> Single-photon sources are essential for quantum networks, enabling applications ranging from quantum key distribution (QKD) to the burgeoning quantum internet. Despite the remarkable advancements, the current reliance of QKD on attenuated coherent (laser) light sources has imposed a fundamental limit on the secret key rate (SKR). This constraint is primarily attributable to the scarcity of single-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02045v1-abstract-full').style.display = 'inline'; document.getElementById('2406.02045v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.02045v1-abstract-full" style="display: none;"> Single-photon sources are essential for quantum networks, enabling applications ranging from quantum key distribution (QKD) to the burgeoning quantum internet. Despite the remarkable advancements, the current reliance of QKD on attenuated coherent (laser) light sources has imposed a fundamental limit on the secret key rate (SKR). This constraint is primarily attributable to the scarcity of single-photon components within coherent light, confined by an inherent upper bound of 1/e. Here, we report high-rate QKD using a high-efficiency single-photon source, enabling an SKR transcending the fundamental rate limit of coherent light. We developed an on-demand, bright semiconductor quantum-dot single-photon source with an efficiency of 0.71(2), exceeding the inherent bound of coherent light by approximately 2.87 dB. Implementing narrow-bandwidth filtering and random polarization modulation, we conducted a field QKD trial over a 14.6(1.1)-dB-loss free-space urban channel, achieving an SKR of 0.00108 bits per pulse. This surpasses the practical limit of coherent-light-based QKD by 2.53 dB. Our findings conclusively demonstrate the superior performance of nanotechnology-based single-photon sources over coherent light for QKD applications, marking a pivotal stride towards the realization of a global quantum internet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02045v1-abstract-full').style.display = 'none'; document.getElementById('2406.02045v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 5 figures, 1 Table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.06863">arXiv:2405.06863</a> <span> [<a href="https://arxiv.org/pdf/2405.06863">pdf</a>, <a href="https://arxiv.org/format/2405.06863">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"> Ultraprecise time-difference measurement via enhanced dual pointers with multiple weak interactions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanqiang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jianchao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+J">Jiahui Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiaomin Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+L">Liantuan Xiao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.06863v1-abstract-short" style="display: inline;"> Standard weak measurement with an assistant pointer and single weak interaction constrains measurement precision and quantity of interaction parameters, and a compelling characterization of quantum effect featuring weak-value amplification (WVA) remains elusive. Here, we theoretically and experimentally demonstrate an enhanced dual-pointer WVA scheme based on multiple weak interactions and variabl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.06863v1-abstract-full').style.display = 'inline'; document.getElementById('2405.06863v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.06863v1-abstract-full" style="display: none;"> Standard weak measurement with an assistant pointer and single weak interaction constrains measurement precision and quantity of interaction parameters, and a compelling characterization of quantum effect featuring weak-value amplification (WVA) remains elusive. Here, we theoretically and experimentally demonstrate an enhanced dual-pointer WVA scheme based on multiple weak interactions and variable spectrum sources. Developing triple weak interactions, momentum P pointer reaches an optimal time-difference precision of $3.34 \times {10^{-5}}$ as at 6 nm spectral width, and intensity I pointer achieves a displacement resolution of 148.8 fm within 400 kHz linewidth. A quantum effect associated with an anomalous weak value is revealed by an observable violation of a Leggett-Garg inequality. The I-pointer weak value is measured to be 1478 using multiple weak interactions and high signal-to-noise detection, achieving a two-order-of-magnitude WVA enhancement compared to standard weak measurement. Our work opens up a practical avenue for minuscule quantumness measurements in challenging environments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.06863v1-abstract-full').style.display = 'none'; document.getElementById('2405.06863v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main text: 6 pages, 6 figures; Supplementary material: 5 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.00767">arXiv:2405.00767</a> <span> [<a href="https://arxiv.org/pdf/2405.00767">pdf</a>, <a href="https://arxiv.org/format/2405.00767">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/s42254-024-00739-8">10.1038/s42254-024-00739-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Aspects of Indefinite Causal Order in Quantum Mechanics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Rozema%2C+L+A">Lee A. Rozema</a>, <a href="/search/quant-ph?searchtype=author&query=Str%C3%B6mberg%2C+T">Teodor Str枚mberg</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+H">Huan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Walther%2C+P">Philip Walther</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.00767v2-abstract-short" style="display: inline;"> In the past decade, the toolkit of quantum information has been expanded to include processes in which the basic operations do not have definite causal relations. Originally considered in the context of the unification of quantum mechanics and general relativity, these causally indefinite processes have been shown to offer advantages in a wide variety of quantum information processing tasks, rangi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00767v2-abstract-full').style.display = 'inline'; document.getElementById('2405.00767v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.00767v2-abstract-full" style="display: none;"> In the past decade, the toolkit of quantum information has been expanded to include processes in which the basic operations do not have definite causal relations. Originally considered in the context of the unification of quantum mechanics and general relativity, these causally indefinite processes have been shown to offer advantages in a wide variety of quantum information processing tasks, ranging from quantum computation to quantum metrology. Here we overview these advantages and the experimental efforts to realise them. We survey both the different experimental techniques employed, as well as theoretical methods developed in support of the experiments, before discussing the interpretations of current experimental results and giving an outlook on the future of the field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00767v2-abstract-full').style.display = 'none'; document.getElementById('2405.00767v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 page review article. Comments welcome!</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Reviews Physics (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.10655">arXiv:2404.10655</a> <span> [<a href="https://arxiv.org/pdf/2404.10655">pdf</a>, <a href="https://arxiv.org/format/2404.10655">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum Simulation of Open Quantum Dynamics via Non-Markovian Quantum State Diffusion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yukai Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+X">Xing Gao</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="2404.10655v2-abstract-short" style="display: inline;"> Quantum simulation of non-Markovian open quantum dynamics is essential but challenging for standard quantum computers due to their non-Hermitian nature, leading to non-unitary evolution, and the limitations of available quantum resources. Here we introduce a hybrid quantum-classical algorithm designed for simulating dissipative dynamics in system with non-Markovian environment. Our approach includ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.10655v2-abstract-full').style.display = 'inline'; document.getElementById('2404.10655v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.10655v2-abstract-full" style="display: none;"> Quantum simulation of non-Markovian open quantum dynamics is essential but challenging for standard quantum computers due to their non-Hermitian nature, leading to non-unitary evolution, and the limitations of available quantum resources. Here we introduce a hybrid quantum-classical algorithm designed for simulating dissipative dynamics in system with non-Markovian environment. Our approach includes formulating a non-Markovian Stochastic Schr枚dinger equation with complex frequency modes (cNMSSE) where the non-Markovianity is characterized by the mode excitation. Following this, we utilize variational quantum simulation to capture the non-unitary evolution within the cNMSSE framework, leading to a substantial reduction in qubit requirements. To demonstrate our approach, we investigated the spin-boson model and dynamic quantum phase transitions (DQPT) within transverse field Ising model (TFIM). Significantly, our findings reveal the enhanced DQPT in TFIM due to non-Markovian behavior. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.10655v2-abstract-full').style.display = 'none'; document.getElementById('2404.10655v2-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.19479">arXiv:2403.19479</a> <span> [<a href="https://arxiv.org/pdf/2403.19479">pdf</a>, <a href="https://arxiv.org/format/2403.19479">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"> Parallel and real-time post-processing for quantum random number generators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiaomin Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+F">Fading Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jiehong Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+Z">Zhijie Song</a>, <a href="/search/quant-ph?searchtype=author&query=luo%2C+Y">Yue luo</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qiqi Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanqiang Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.19479v1-abstract-short" style="display: inline;"> Quantum systems are particularly suited for generating true randomness due to their inherent unpredictability, which can be justified on physical principles. However, practical implementations of Quantum RNGs (QRNGs) are always subject to noise, or uncontrollable influences, diminishing the quality of raw randomness produced. This necessitates post-processing to convert raw output into genuine ran… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.19479v1-abstract-full').style.display = 'inline'; document.getElementById('2403.19479v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.19479v1-abstract-full" style="display: none;"> Quantum systems are particularly suited for generating true randomness due to their inherent unpredictability, which can be justified on physical principles. However, practical implementations of Quantum RNGs (QRNGs) are always subject to noise, or uncontrollable influences, diminishing the quality of raw randomness produced. This necessitates post-processing to convert raw output into genuine randomness. In current QRNG implementations, the critical issue of seed updating is often overlooked, risking security vulnerabilities due to increased security parameters when seeds are reused in post-processing, and frequent seed updates fail to yield net randomness, while reusing seeds relies on the assumption that the original sequence inputs are independent.In this work, we have provided a specific scheme for seed updates that balances practicality and security, exploring the parallel and real-time implementation of multiple seed real-time updating toeplitz hash extractors in an FPGA to achieve parallel QRNGs, focusing on efficient hardware computation resource use. Through logic optimization, we achieved a greater number of parallel channels and a post-processing matrix size three times larger than previous works on the same FPGA platform, utilizing fewer logic resources. This resulted in a higher rate of random number generation and enhanced security. Furthermore, with the use of higher-performance ADCs, we attained a random number production rate exceeding 20Gbps.High-speed random number transfer and seed updating were achieved using the PCIe high-speed interface.This marks a significant step toward chip-based parallel QRNGs, enhancing the practicality of CV QRNGs in trusted, device-independent, and semi-device-independent scenarios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.19479v1-abstract-full').style.display = 'none'; document.getElementById('2403.19479v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.07850">arXiv:2403.07850</a> <span> [<a href="https://arxiv.org/pdf/2403.07850">pdf</a>, <a href="https://arxiv.org/format/2403.07850">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/10.1063/5.0209294">10.1063/5.0209294 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Laser-written waveguide-integrated coherent spins in diamond </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanzhao Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Hadden%2C+J+P">John P. Hadden</a>, <a href="/search/quant-ph?searchtype=author&query=Gorrini%2C+F">Federico Gorrini</a>, <a href="/search/quant-ph?searchtype=author&query=Coccia%2C+G">Giulio Coccia</a>, <a href="/search/quant-ph?searchtype=author&query=Bharadwaj%2C+V">Vibhav Bharadwaj</a>, <a href="/search/quant-ph?searchtype=author&query=Kavatamane%2C+V+K">Vinaya Kumar Kavatamane</a>, <a href="/search/quant-ph?searchtype=author&query=Alam%2C+M+S">Mohammad Sahnawaz Alam</a>, <a href="/search/quant-ph?searchtype=author&query=Ramponi%2C+R">Roberta Ramponi</a>, <a href="/search/quant-ph?searchtype=author&query=Barclay%2C+P+E">Paul E. Barclay</a>, <a href="/search/quant-ph?searchtype=author&query=Chiappini%2C+A">Andrea Chiappini</a>, <a href="/search/quant-ph?searchtype=author&query=Ferrari%2C+M">Maurizio Ferrari</a>, <a href="/search/quant-ph?searchtype=author&query=Kubanek%2C+A">Alexander Kubanek</a>, <a href="/search/quant-ph?searchtype=author&query=Bifone%2C+A">Angelo Bifone</a>, <a href="/search/quant-ph?searchtype=author&query=Eaton%2C+S+M">Shane M. Eaton</a>, <a href="/search/quant-ph?searchtype=author&query=Bennett%2C+A+J">Anthony J. Bennett</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.07850v1-abstract-short" style="display: inline;"> Quantum emitters, such as the negatively charged nitrogen-vacancy center in diamond, are attractive for quantum technologies such as nano-sensing, quantum information processing, and as a non-classical light source. However, it is still challenging to position individual emitters in photonic structures whilst preserving the spin coherence properties of the defect. In this paper, we investigate sin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.07850v1-abstract-full').style.display = 'inline'; document.getElementById('2403.07850v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.07850v1-abstract-full" style="display: none;"> Quantum emitters, such as the negatively charged nitrogen-vacancy center in diamond, are attractive for quantum technologies such as nano-sensing, quantum information processing, and as a non-classical light source. However, it is still challenging to position individual emitters in photonic structures whilst preserving the spin coherence properties of the defect. In this paper, we investigate single and ensemble waveguide-integrated nitrogen-vacancy centers in diamond fabricated by femtosecond laser writing followed by thermal annealing. Their spin coherence properties are systematically investigated and are shown to be comparable to native nitrogen-vacancy centers in diamond. This method paves the way for the fabrication of coherent spins integrated within photonic devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.07850v1-abstract-full').style.display = 'none'; document.getElementById('2403.07850v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> APL Photonics 9, 076103 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.07974">arXiv:2402.07974</a> <span> [<a href="https://arxiv.org/pdf/2402.07974">pdf</a>, <a href="https://arxiv.org/format/2402.07974">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Experimental roadmap for optimal state transfer and entanglement generation in power-law systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+A+Y">Andrew Y. Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Young%2C+J+T">Jeremy T. Young</a>, <a href="/search/quant-ph?searchtype=author&query=Belyansky%2C+R">Ron Belyansky</a>, <a href="/search/quant-ph?searchtype=author&query=Bienias%2C+P">Przemyslaw Bienias</a>, <a href="/search/quant-ph?searchtype=author&query=Gorshkov%2C+A+V">Alexey V. Gorshkov</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="2402.07974v1-abstract-short" style="display: inline;"> Experimental systems with power-law interactions have recently garnered interest as promising platforms for quantum information processing. Such systems are capable of spreading entanglement superballistically and achieving an asymptotic speed-up over locally interacting systems. Recently, protocols developed by Eldredge et al. [Phys. Rev. Lett. 119, 170503 (2017)] and Tran et al. [Phys. Rev. X 11… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.07974v1-abstract-full').style.display = 'inline'; document.getElementById('2402.07974v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.07974v1-abstract-full" style="display: none;"> Experimental systems with power-law interactions have recently garnered interest as promising platforms for quantum information processing. Such systems are capable of spreading entanglement superballistically and achieving an asymptotic speed-up over locally interacting systems. Recently, protocols developed by Eldredge et al. [Phys. Rev. Lett. 119, 170503 (2017)] and Tran et al. [Phys. Rev. X 11, 031016 (2021)] for the task of transferring a quantum state between distant particles quickly were shown to be optimal and saturate theoretical bounds. However, the implementation of these protocols in physical systems with long-range interactions remains to be fully realized. In this work, we provide an experimental roadmap towards realizing fast state-transfer protocols in three classes of atomic and molecular systems with dipolar interactions: polar molecules composed of alkali-metal dimers, neutral atoms in excited Rydberg states, and atoms with strong magnetic moments (e.g. dysprosium). As a guide to near-term experimental implementation, we numerically evaluate the tradeoffs between the two protocols for small system sizes and develop methods to address potential crosstalk errors that may arise during the execution of the protocols. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.07974v1-abstract-full').style.display = 'none'; document.getElementById('2402.07974v1-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 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">13+5 pages. Comments 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/2402.06422">arXiv:2402.06422</a> <span> [<a href="https://arxiv.org/pdf/2402.06422">pdf</a>, <a href="https://arxiv.org/format/2402.06422">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> <p class="title is-5 mathjax"> Determining Strain Components in a Diamond Waveguide from Zero-Field ODMR Spectra of NV$^{-}$ Center Ensembles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Alam%2C+M+S">M. Sahnawaz Alam</a>, <a href="/search/quant-ph?searchtype=author&query=Gorrini%2C+F">Federico Gorrini</a>, <a href="/search/quant-ph?searchtype=author&query=Gawe%C5%82czyk%2C+M">Micha艂 Gawe艂czyk</a>, <a href="/search/quant-ph?searchtype=author&query=Wigger%2C+D">Daniel Wigger</a>, <a href="/search/quant-ph?searchtype=author&query=Coccia%2C+G">Giulio Coccia</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanzhao Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Shahbazi%2C+S">Sajedeh Shahbazi</a>, <a href="/search/quant-ph?searchtype=author&query=Bharadwaj%2C+V">Vibhav Bharadwaj</a>, <a href="/search/quant-ph?searchtype=author&query=Kubanek%2C+A">Alexander Kubanek</a>, <a href="/search/quant-ph?searchtype=author&query=Ramponi%2C+R">Roberta Ramponi</a>, <a href="/search/quant-ph?searchtype=author&query=Barclay%2C+P+E">Paul E. Barclay</a>, <a href="/search/quant-ph?searchtype=author&query=Bennett%2C+A+J">Anthony J. Bennett</a>, <a href="/search/quant-ph?searchtype=author&query=Hadden%2C+J+P">John P. Hadden</a>, <a href="/search/quant-ph?searchtype=author&query=Bifone%2C+A">Angelo Bifone</a>, <a href="/search/quant-ph?searchtype=author&query=Eaton%2C+S+M">Shane M. Eaton</a>, <a href="/search/quant-ph?searchtype=author&query=Machnikowski%2C+P">Pawe艂 Machnikowski</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="2402.06422v2-abstract-short" style="display: inline;"> The negatively charged nitrogen-vacancy (NV$^{-}$) center in diamond has shown great potential in nanoscale sensing and quantum information processing due to its rich spin physics. An efficient coupling with light, providing strong luminescence, is crucial for realizing these applications. Laser-written waveguides in diamond promote NV$^{-}$ creation and improve their coupling to light but, at the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.06422v2-abstract-full').style.display = 'inline'; document.getElementById('2402.06422v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.06422v2-abstract-full" style="display: none;"> The negatively charged nitrogen-vacancy (NV$^{-}$) center in diamond has shown great potential in nanoscale sensing and quantum information processing due to its rich spin physics. An efficient coupling with light, providing strong luminescence, is crucial for realizing these applications. Laser-written waveguides in diamond promote NV$^{-}$ creation and improve their coupling to light but, at the same time, induce strain in the crystal. The induced strain contributes to light guiding but also affects the energy levels of NV$^{-}$ centers. We probe NV$^{-}$ spin states experimentally with the commonly used continuous-wave zero-field optically detected magnetic resonance (ODMR). In our waveguides, the ODMR spectra are shifted, split, and consistently asymmetric, which we attribute to the impact of local strain. To understand these features, we model ensemble ODMR signals in the presence of strain. By fitting the model results to the experimentally collected ODMR data, we determine the strain tensor components at different positions, thus determining the strain profile across the waveguide. This shows that zero-field ODMR spectroscopy can be used as a strain imaging tool. The resulting strain within the waveguide is dominated by a compressive axial component transverse to the waveguide structure, with a smaller contribution from vertical and shear strain components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.06422v2-abstract-full').style.display = 'none'; document.getElementById('2402.06422v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">12 pages, 7 figures + Supplementary Information (6 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/2401.04724">arXiv:2401.04724</a> <span> [<a href="https://arxiv.org/pdf/2401.04724">pdf</a>, <a href="https://arxiv.org/format/2401.04724">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="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> A parametrically programmable delay line for microwave photons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Makihara%2C+T">Takuma Makihara</a>, <a href="/search/quant-ph?searchtype=author&query=Lee%2C+N">Nathan Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yudan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+W">Wenyan Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Safavi-Naeini%2C+A+H">Amir H. Safavi-Naeini</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="2401.04724v3-abstract-short" style="display: inline;"> Delay lines that store quantum information are crucial for advancing quantum repeaters and hardware efficient quantum computers. Traditionally, they are realized as extended systems that support wave propagation but provide limited control over the propagating fields. Here, we introduce a parametrically addressed delay line for microwave photons that provides a high level of control over the store… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04724v3-abstract-full').style.display = 'inline'; document.getElementById('2401.04724v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04724v3-abstract-full" style="display: none;"> Delay lines that store quantum information are crucial for advancing quantum repeaters and hardware efficient quantum computers. Traditionally, they are realized as extended systems that support wave propagation but provide limited control over the propagating fields. Here, we introduce a parametrically addressed delay line for microwave photons that provides a high level of control over the stored pulses. By parametrically driving a three-wave mixing circuit element that is weakly hybridized with an ensemble of resonators, we engineer a spectral response that simulates that of a physical delay line, while providing fast control over the delay line's properties. We demonstrate this novel degree of control by choosing which photon echo to emit, translating pulses in time, and even swapping two pulses, all with pulse energies on the order of a single photon. We also measure the noise added from our parametric interactions and find it is much less than one photon. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04724v3-abstract-full').style.display = 'none'; document.getElementById('2401.04724v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">15 pages, 11 figures; v3: more update</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.02128">arXiv:2401.02128</a> <span> [<a href="https://arxiv.org/pdf/2401.02128">pdf</a>, <a href="https://arxiv.org/format/2401.02128">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="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Correlated sensing with a solid-state quantum multi-sensor system for atomic-scale structural analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ji%2C+W">Wentao Ji</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Z">Zhaoxin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuhang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Z">Zhihao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Jingyang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+S">Siheng Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+P">Pei Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+M">Mengqi Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Xia%2C+K">Kangwei Xia</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+F">Fazhan Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Ya Wang</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="2401.02128v1-abstract-short" style="display: inline;"> Developing superior quantum sensing strategies ranging from ultra-high precision measurement to complex structural analysis is at the heart of quantum technologies. While strategies using quantum resources, such as entanglement among sensors, to enhance the sensing precision have been abundantly demonstrated, the signal correlation among quantum sensors is rarely exploited. Here we develop a novel… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.02128v1-abstract-full').style.display = 'inline'; document.getElementById('2401.02128v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.02128v1-abstract-full" style="display: none;"> Developing superior quantum sensing strategies ranging from ultra-high precision measurement to complex structural analysis is at the heart of quantum technologies. While strategies using quantum resources, such as entanglement among sensors, to enhance the sensing precision have been abundantly demonstrated, the signal correlation among quantum sensors is rarely exploited. Here we develop a novel sensing paradigm exploiting the signal correlation among multiple quantum sensors to resolve overlapping signals from multiple targets that individual sensors can't resolve and complex structural construction struggles with. With three nitrogen-vacancy centers as a quantum electrometer system, we demonstrate this multi-sensor paradigm by resolving individual defects' fluctuating electric fields from ensemble signals. We image the three-dimensional distribution of 16 dark electronic point-defects in diamond with accuracy approaching 1.7 nm via a GPS-like localization method. Furthermore, we obtain the real-time charge dynamics of individual point defects and visualize how the dynamics induce the well-known optical spectral diffusion. The multi-sensor paradigm extends the quantum sensing toolbox and offers new possibilities for structural analysis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.02128v1-abstract-full').style.display = 'none'; document.getElementById('2401.02128v1-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.13880">arXiv:2312.13880</a> <span> [<a href="https://arxiv.org/pdf/2312.13880">pdf</a>, <a href="https://arxiv.org/format/2312.13880">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of many-body dynamical localization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanliang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Dhar%2C+S">Sudipta Dhar</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+A">Ang Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zekai Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+H">Hepeng Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Horvath%2C+M">Milena Horvath</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+L">Lei Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Landini%2C+M">Manuele Landini</a>, <a href="/search/quant-ph?searchtype=author&query=N%C3%A4gerl%2C+H">Hanns-Christoph N盲gerl</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="2312.13880v1-abstract-short" style="display: inline;"> The quantum kicked rotor is a paradigmatic model system in quantum physics. As a driven quantum system, it is used to study the transition from the classical to the quantum world and to elucidate the emergence of chaos and diffusion. In contrast to its classical counterpart, it features dynamical localization, specifically Anderson localization in momentum space. The interacting many-body kicked r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.13880v1-abstract-full').style.display = 'inline'; document.getElementById('2312.13880v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.13880v1-abstract-full" style="display: none;"> The quantum kicked rotor is a paradigmatic model system in quantum physics. As a driven quantum system, it is used to study the transition from the classical to the quantum world and to elucidate the emergence of chaos and diffusion. In contrast to its classical counterpart, it features dynamical localization, specifically Anderson localization in momentum space. The interacting many-body kicked rotor is believed to break localization, as recent experiments suggest. Here, we present evidence for many-body dynamical localization for the Lieb-Liniger version of the many-body quantum kicked rotor. After some initial evolution, the momentum distribution of interacting quantum-degenerate bosonic atoms in one-dimensional geometry, kicked hundreds of times by means of a pulsed sinusoidal potential, stops spreading. We quantify the arrested evolution by analysing the energy and the information entropy of the system as the interaction strength is tuned. In the limiting cases of vanishing and strong interactions, the first-order correlation function exhibits a very different decay behavior. Our results shed light on the boundary between the classical, chaotic world and the realm of quantum physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.13880v1-abstract-full').style.display = 'none'; document.getElementById('2312.13880v1-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">13 pages, 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.10298">arXiv:2312.10298</a> <span> [<a href="https://arxiv.org/pdf/2312.10298">pdf</a>, <a href="https://arxiv.org/format/2312.10298">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="Emerging Technologies">cs.ET</span> </div> </div> <p class="title is-5 mathjax"> Integrated Qubit Reuse and Circuit Cutting for Large Quantum Circuit Evaluation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pawar%2C+A">Aditya Pawar</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yingheng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Mo%2C+Z">Zewei Mo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Youtao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+X">Xulong Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+J">Jun 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="2312.10298v1-abstract-short" style="display: inline;"> Quantum computing has recently emerged as a promising computing paradigm for many application domains. However, the size of quantum circuits that can run with high fidelity is constrained by the limited quantity and quality of physical qubits. Recently proposed schemes, such as wire cutting and qubit reuse, mitigate the problem but produce sub-optimal results as they address the problem individual… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10298v1-abstract-full').style.display = 'inline'; document.getElementById('2312.10298v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.10298v1-abstract-full" style="display: none;"> Quantum computing has recently emerged as a promising computing paradigm for many application domains. However, the size of quantum circuits that can run with high fidelity is constrained by the limited quantity and quality of physical qubits. Recently proposed schemes, such as wire cutting and qubit reuse, mitigate the problem but produce sub-optimal results as they address the problem individually. In addition, gate cutting, an alternative circuit-cutting strategy, has not been fully explored in the field. In this paper, we propose IQRC, an integrated approach that exploits qubit reuse and circuit cutting (including wire cutting and gate cutting) to run large circuits on small quantum computers. Circuit-cutting techniques introduce non-negligible post-processing overhead, which increases exponentially with the number of cuts. IQRC exploits qubit reuse to find better cutting solutions to minimize the cut numbers and thus the post-processing overhead. Our evaluation results show that on average we reduce the number of cuts by 34\% and additional reduction when considering gate cuts. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10298v1-abstract-full').style.display = 'none'; document.getElementById('2312.10298v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 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/2312.02854">arXiv:2312.02854</a> <span> [<a href="https://arxiv.org/pdf/2312.02854">pdf</a>, <a href="https://arxiv.org/format/2312.02854">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/10.1088/0256-307X/41/12/120302">10.1088/0256-307X/41/12/120302 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Locally purified density operators for noisy quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo 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="2312.02854v3-abstract-short" style="display: inline;"> Simulating open quantum systems is essential for exploring novel quantum phenomena and evaluating noisy quantum circuits. In this Letter, we address the problem of whether mixed states generated from noisy quantum circuits can be efficiently represented by locally purified density operators (LPDOs). We map an LPDO of $N$ qubits to a pure state of size $2\times N$ defined on a ladder and introduce… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.02854v3-abstract-full').style.display = 'inline'; document.getElementById('2312.02854v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.02854v3-abstract-full" style="display: none;"> Simulating open quantum systems is essential for exploring novel quantum phenomena and evaluating noisy quantum circuits. In this Letter, we address the problem of whether mixed states generated from noisy quantum circuits can be efficiently represented by locally purified density operators (LPDOs). We map an LPDO of $N$ qubits to a pure state of size $2\times N$ defined on a ladder and introduce a unified method for managing virtual and Kraus bonds. We numerically simulate noisy random quantum circuits with depths up to $d=40$ using fidelity and entanglement entropy as accuracy measures. LPDO representation proves to be effective in describing mixed states in both quantum and classical regions but encounters significant challenges at the quantum-classical critical point, limiting its applicability to the quantum region exclusively. In contrast, the matrix product operator (MPO) successfully characterizes the entanglement trend throughout the simulation, while truncation in MPOs breaks the positivity condition required for a physical density matrix. This work advances our understanding of efficient mixed-state representation in open quantum systems and provides insights into the entanglement structure of noisy quantum circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.02854v3-abstract-full').style.display = 'none'; document.getElementById('2312.02854v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">13 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Chin. Phys. Lett. 41, 120302 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.12619">arXiv:2311.12619</a> <span> [<a href="https://arxiv.org/pdf/2311.12619">pdf</a>, <a href="https://arxiv.org/format/2311.12619">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> </div> </div> <p class="title is-5 mathjax"> Two-dimensional symmetry-protected topological phases and transitions in open quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuxuan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Ashida%2C+Y">Yuto Ashida</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.12619v4-abstract-short" style="display: inline;"> We investigate the influence of local decoherence on a symmetry-protected topological (SPT) phase of the two-dimensional (2D) cluster state. Mapping the 2D cluster state under decoherence to a classical spin model, we show a topological phase transition of a $\mathbb{Z}_2^{(0)}\times\mathbb{Z}_{2}^{(1)}$ SPT phase into the trivial phase occurring at a finite decoherence strength. To characterize t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.12619v4-abstract-full').style.display = 'inline'; document.getElementById('2311.12619v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.12619v4-abstract-full" style="display: none;"> We investigate the influence of local decoherence on a symmetry-protected topological (SPT) phase of the two-dimensional (2D) cluster state. Mapping the 2D cluster state under decoherence to a classical spin model, we show a topological phase transition of a $\mathbb{Z}_2^{(0)}\times\mathbb{Z}_{2}^{(1)}$ SPT phase into the trivial phase occurring at a finite decoherence strength. To characterize the phase transition, we employ three distinct diagnostic methods, namely, the relative entropy between two decohered SPT states with different topological edge states, the strange correlation function of $\mathbb{Z}_2^{(1)}$ charge, and the multipartite negativity of the mixed state on a disk. All the diagnostics can be obtained as certain thermodynamic quantities in the corresponding classical model, and the results of three diagnostic tests are consistent with each other. Given that the 2D cluster state possesses universal computational capabilities in the context of measurement-based quantum computation, the topological phase transition found here can also be interpreted as a transition in the computational power. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.12619v4-abstract-full').style.display = 'none'; document.getElementById('2311.12619v4-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages + 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.08347">arXiv:2311.08347</a> <span> [<a href="https://arxiv.org/pdf/2311.08347">pdf</a>, <a href="https://arxiv.org/format/2311.08347">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> High-efficiency single-photon source above the loss-tolerant threshold for efficient linear optical quantum computing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ding%2C+X">Xing Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yong-Peng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+M">Mo-Chi Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+G">Geng-Yan Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+J">Jun-Yi Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Ge%2C+Z">Zhen-Xuan Ge</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qi-Hang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hua-Liang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+L">Lin-Jun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Hui Wang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yu-Ming He</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</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="2311.08347v2-abstract-short" style="display: inline;"> Photon loss is the biggest enemy for scalable photonic quantum information processing. This problem can be tackled by using quantum error correction, provided that the overall photon loss is below a threshold of 1/3. However, all reported on-demand and indistinguishable single-photon sources still fall short of this threshold. Here, by using tailor shaped laser pulse excitation on a high-quantum e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08347v2-abstract-full').style.display = 'inline'; document.getElementById('2311.08347v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.08347v2-abstract-full" style="display: none;"> Photon loss is the biggest enemy for scalable photonic quantum information processing. This problem can be tackled by using quantum error correction, provided that the overall photon loss is below a threshold of 1/3. However, all reported on-demand and indistinguishable single-photon sources still fall short of this threshold. Here, by using tailor shaped laser pulse excitation on a high-quantum efficiency single quantum dot deterministically coupled to a tunable open microcavity, we demonstrate a high-performance source with a single-photon purity of 0.9795(6), photon indistinguishability of 0.9856(13), and an overall system efficiency of 0.712(18), simultaneously. This source for the first time reaches the efficiency threshold for scalable photonic quantum computing. With this source, we further demonstrate 1.89(14) dB intensity squeezing, and consecutive 40-photon events with 1.67 mHz count rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08347v2-abstract-full').style.display = 'none'; document.getElementById('2311.08347v2-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.08063">arXiv:2311.08063</a> <span> [<a href="https://arxiv.org/pdf/2311.08063">pdf</a>, <a href="https://arxiv.org/ps/2311.08063">ps</a>, <a href="https://arxiv.org/format/2311.08063">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 mechanical squeezing in an optomechanical system via backward stimulated Brillouin scattering </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Shan-Shan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+N">Na-Na Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yong-Rui Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+H">Huan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+Y">Yong Ma</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.08063v1-abstract-short" style="display: inline;"> We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon-photon interaction via the backward stimulated Brillouin scattering (BSBS) process. The coherent photon-phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08063v1-abstract-full').style.display = 'inline'; document.getElementById('2311.08063v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.08063v1-abstract-full" style="display: none;"> We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon-photon interaction via the backward stimulated Brillouin scattering (BSBS) process. The coherent photon-phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing mechanical oscillator. The squeezing degree and the robustness to the thermal noises of the Duffing mechanical mode can be enhanced greatly. When the Duffing nonlinearity is weak, the squeezing degree of the mechanical mode in the presence of BSBS can be improved more than one order of magnitude compared with the absence of BSBS. Our scheme may be extended to other quantum systems to study novel quantum effects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.08063v1-abstract-full').style.display = 'none'; document.getElementById('2311.08063v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.18190">arXiv:2310.18190</a> <span> [<a href="https://arxiv.org/pdf/2310.18190">pdf</a>, <a href="https://arxiv.org/format/2310.18190">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.110.014109">10.1103/PhysRevB.110.014109 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Photo-dynamics of quantum emitters in aluminum nitride </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanzhao Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Hadden%2C+J+P">John P. Hadden</a>, <a href="/search/quant-ph?searchtype=author&query=Clark%2C+R+N">Rachel N. Clark</a>, <a href="/search/quant-ph?searchtype=author&query=Bishop%2C+S+G">Samuel G. Bishop</a>, <a href="/search/quant-ph?searchtype=author&query=Bennett%2C+A+J">Anthony J. Bennett</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="2310.18190v1-abstract-short" style="display: inline;"> Aluminum nitride is a technologically important wide bandgap semiconductor which has been shown to host bright quantum emitters. In this paper, we probe the photodynamics of quantum emitters in aluminum nitride using photon emission correlations and time-resolved spectroscopy. We identify that each emitter contains as many as 6 internal energy levels with distinct laser power-dependent behaviors.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.18190v1-abstract-full').style.display = 'inline'; document.getElementById('2310.18190v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.18190v1-abstract-full" style="display: none;"> Aluminum nitride is a technologically important wide bandgap semiconductor which has been shown to host bright quantum emitters. In this paper, we probe the photodynamics of quantum emitters in aluminum nitride using photon emission correlations and time-resolved spectroscopy. We identify that each emitter contains as many as 6 internal energy levels with distinct laser power-dependent behaviors. Power-dependent shelving and de-shelving processes, such as optically induced ionization and recombination are considered, indicating complex optical dynamics associated with the spontaneous and optically pumped transitions. State population dynamics simulations qualitatively explain the temporal behaviours of the quantum emitters, revealing that those with pump-dependent de-shelving processes can saturate at significantly higher intensities, resulting in bright room-temperature quantum light emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.18190v1-abstract-full').style.display = 'none'; document.getElementById('2310.18190v1-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages. 5 figures in main text, 3 in supplementary info</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, 014109 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.09538">arXiv:2310.09538</a> <span> [<a href="https://arxiv.org/pdf/2310.09538">pdf</a>, <a href="https://arxiv.org/format/2310.09538">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/OE.501645">10.1364/OE.501645 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Comparison of multi-mode Hong-Ou-Mandel interference and multi-slit interference </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Z">Zi-Xiang Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Z">Zi-Qi Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+C">Chunling Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Shimizu%2C+R">Ryosuke Shimizu</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+R">Rui-Bo Jin</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.09538v1-abstract-short" style="display: inline;"> Hong-Ou-Mandel (HOM) interference of multi-mode frequency entangled states plays a crucial role in quantum metrology. However, as the number of modes increases, the HOM interference pattern becomes increasingly complex, making it challenging to comprehend intuitively. To overcome this problem, we present the theory and simulation of multi-mode-HOM interference (MM-HOMI) and compare it to multi-sli… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.09538v1-abstract-full').style.display = 'inline'; document.getElementById('2310.09538v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.09538v1-abstract-full" style="display: none;"> Hong-Ou-Mandel (HOM) interference of multi-mode frequency entangled states plays a crucial role in quantum metrology. However, as the number of modes increases, the HOM interference pattern becomes increasingly complex, making it challenging to comprehend intuitively. To overcome this problem, we present the theory and simulation of multi-mode-HOM interference (MM-HOMI) and compare it to multi-slit interference (MSI). We find that these two interferences have a strong mapping relationship and are determined by two factors: the envelope factor and the details factor. The envelope factor is contributed by the single-mode HOM interference (single-slit diffraction) for MM-HOMI (MSI). The details factor is given by $\sin(Nx)/ \sin(x)$ ($[\sin(Nv)/\sin(v)]^2$) for MM-HOMI (MSI), where $N$ is the mode (slit) number and $x (v)$ is the phase spacing of two adjacent spectral modes (slits). As a potential application, we demonstrate that the square root of the maximal Fisher information in MM-HOMI increases linearly with the number of modes, indicating that MM-HOMI is a powerful tool for enhancing precision in time estimation. We also discuss multi-mode Mach-Zehnder interference, multi-mode NOON-state interference, and the extended Wiener-Khinchin theorem. This work may provide an intuitive understanding of MM-HOMI patterns and promote the application of MM-HOMI in quantum metrology. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.09538v1-abstract-full').style.display = 'none'; document.getElementById('2310.09538v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Optics Express 31(20), 32849-32864 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.08838">arXiv:2310.08838</a> <span> [<a href="https://arxiv.org/pdf/2310.08838">pdf</a>, <a href="https://arxiv.org/format/2310.08838">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"> Higher-dimensional symmetric informationally complete measurement via programmable photonic integrated optics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Feng%2C+L">Lan-Tian Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Min Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+M">Ming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+Y">Yu-Jie Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+Y">Yu-Yang Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+Z">Zhibo Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+F">Fang-Wen Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+D">Dao-Xin Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Tavakoli%2C+A">Armin Tavakoli</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+X">Xi-Feng Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng 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="2310.08838v2-abstract-short" style="display: inline;"> Symmetric informationally complete measurements are both important building blocks in many quantum information protocols and the seminal example of a generalised, non-orthogonal, quantum measurement. In higher-dimensional systems, these measurements become both increasingly interesting and increasingly complex to implement. Here, we demonstrate an integrated quantum photonic platform to realize su… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08838v2-abstract-full').style.display = 'inline'; document.getElementById('2310.08838v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.08838v2-abstract-full" style="display: none;"> Symmetric informationally complete measurements are both important building blocks in many quantum information protocols and the seminal example of a generalised, non-orthogonal, quantum measurement. In higher-dimensional systems, these measurements become both increasingly interesting and increasingly complex to implement. Here, we demonstrate an integrated quantum photonic platform to realize such a measurement on three-level quantum systems. The device operates at the high fidelities necessary for verifying a genuine many-outcome quantum measurement, performing near-optimal quantum state discrimination, and beating the projective limit in quantum random number generation. Moreover, it is programmable and can readily implement other quantum measurements at similarly high quality. Our work paves the way for the implementation of sophisticated higher-dimensional quantum measurements that go beyond the traditional orthogonal projections. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.08838v2-abstract-full').style.display = 'none'; document.getElementById('2310.08838v2-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages,13 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.16381">arXiv:2307.16381</a> <span> [<a href="https://arxiv.org/pdf/2307.16381">pdf</a>, <a href="https://arxiv.org/format/2307.16381">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/s42005-024-01813-4">10.1038/s42005-024-01813-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum State Tomography with Locally Purified Density Operators and Local Measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo 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="2307.16381v3-abstract-short" style="display: inline;"> Understanding quantum systems is of significant importance for assessing the performance of quantum hardware and software, as well as exploring quantum control and quantum sensing. An efficient representation of quantum states enables realizing quantum state tomography with minimal measurements. In this study, we propose an alternative approach to state tomography that uses tensor network represen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.16381v3-abstract-full').style.display = 'inline'; document.getElementById('2307.16381v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.16381v3-abstract-full" style="display: none;"> Understanding quantum systems is of significant importance for assessing the performance of quantum hardware and software, as well as exploring quantum control and quantum sensing. An efficient representation of quantum states enables realizing quantum state tomography with minimal measurements. In this study, we propose an alternative approach to state tomography that uses tensor network representations of mixed states through locally purified density operators and employs a classical data postprocessing algorithm requiring only local measurements. Through numerical simulations of one-dimensional pure and mixed states and two-dimensional pure states up to size $8\times 8$, we demonstrate the efficiency, accuracy, and robustness of our proposed methods. Experiments on the IBM and Quafu Quantum platforms complement these numerical simulations. Our study opens avenues in quantum state tomography for two-dimensional systems using tensor network formalism. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.16381v3-abstract-full').style.display = 'none'; document.getElementById('2307.16381v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Commun. Phys. 7, 322 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.02868">arXiv:2307.02868</a> <span> [<a href="https://arxiv.org/pdf/2307.02868">pdf</a>, <a href="https://arxiv.org/format/2307.02868">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="Chaotic Dynamics">nlin.CD</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/10.1063/5.0157639">10.1063/5.0157639 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-speed photon correlation monitoring of amplified quantum noise by chaos using deep-learning balanced homodyne detection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanqiang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Z">Zinan Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jianchao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+C">Chenyu Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiaomin Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.02868v2-abstract-short" style="display: inline;"> Precision experimental determination of photon correlation requires the massive amounts of data and extensive measurement time. We present a technique to monitor second-order photon correlation $g^{(2)}(0)$ of amplified quantum noise based on wideband balanced homodyne detection and deep-learning acceleration. The quantum noise is effectively amplified by an injection of weak chaotic laser and the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02868v2-abstract-full').style.display = 'inline'; document.getElementById('2307.02868v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.02868v2-abstract-full" style="display: none;"> Precision experimental determination of photon correlation requires the massive amounts of data and extensive measurement time. We present a technique to monitor second-order photon correlation $g^{(2)}(0)$ of amplified quantum noise based on wideband balanced homodyne detection and deep-learning acceleration. The quantum noise is effectively amplified by an injection of weak chaotic laser and the $g^{(2)}(0)$ of the amplified quantum noise is measured with a real-time sample rate of 1.4 GHz. We also exploit a photon correlation convolutional neural network accelerating correlation data using a few quadrature fluctuations to perform a parallel processing of the $g^{(2)}(0)$ for various chaos injection intensities and effective bandwidths. The deep-learning method accelerates the $g^{(2)}(0)$ experimental acquisition with a high accuracy, estimating 6107 sets of photon correlation data with a mean square error of 0.002 in 22 seconds and achieving a three orders of magnitude acceleration in data acquisition time. This technique contributes to a high-speed and precision coherence evaluation of entropy source in secure communication and quantum imaging. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02868v2-abstract-full').style.display = 'none'; document.getElementById('2307.02868v2-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 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/2307.02189">arXiv:2307.02189</a> <span> [<a href="https://arxiv.org/pdf/2307.02189">pdf</a>, <a href="https://arxiv.org/format/2307.02189">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"> Heralded three-photon entanglement from a single-photon source on a photonic chip </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Si Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+L">Li-Chao Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yong-Peng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+X">Xue-Mei Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+X">Xing Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xiang You</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+J">Jian Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yun-Fei Wang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yu-Ming He</a>, <a href="/search/quant-ph?searchtype=author&query=Renema%2C+J+J">Jelmer J. Renema</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Hui Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</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="2307.02189v1-abstract-short" style="display: inline;"> In the quest to build general-purpose photonic quantum computers, fusion-based quantum computation has risen to prominence as a promising strategy. This model allows a ballistic construction of large cluster states which are universal for quantum computation, in a scalable and loss-tolerant way without feed-forward, by fusing many small n-photon entangled resource states. However, a key obstacle t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02189v1-abstract-full').style.display = 'inline'; document.getElementById('2307.02189v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.02189v1-abstract-full" style="display: none;"> In the quest to build general-purpose photonic quantum computers, fusion-based quantum computation has risen to prominence as a promising strategy. This model allows a ballistic construction of large cluster states which are universal for quantum computation, in a scalable and loss-tolerant way without feed-forward, by fusing many small n-photon entangled resource states. However, a key obstacle to this architecture lies in efficiently generating the required essential resource states on photonic chips. One such critical seed state that has not yet been achieved is the heralded three-photon Greenberger-Horne-Zeilinger (3-GHZ) state. Here, we address this elementary resource gap, by reporting the first experimental realization of a heralded dual-rail encoded 3-GHZ state. Our implementation employs a low-loss and fully programmable photonic chip that manipulates six indistinguishable single photons of wavelengths in the telecommunication regime. Conditional on the heralding detection, we obtain the desired 3-GHZ state with a fidelity 0.573+-0.024. Our work marks an important step for the future fault-tolerant photonic quantum computing, leading to the acceleration of building a large-scale optical quantum computer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02189v1-abstract-full').style.display = 'none'; document.getElementById('2307.02189v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted. 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/2306.13495">arXiv:2306.13495</a> <span> [<a href="https://arxiv.org/pdf/2306.13495">pdf</a>, <a href="https://arxiv.org/format/2306.13495">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"> Irreversible encoding on high-dimensional entanglement improves quantum communication </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+H">Hao Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Pauwels%2C+J">Jef Pauwels</a>, <a href="/search/quant-ph?searchtype=author&query=Cruzeiro%2C+E+Z">Emmanuel Zambrini Cruzeiro</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Min Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yu-Feng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Tavakoli%2C+A">Armin Tavakoli</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.13495v2-abstract-short" style="display: inline;"> Shared entanglement can significantly amplify classical correlations between systems interacting over a limited quantum channel. A natural avenue is to use entanglement of the same dimension as the channel because this allows for unitary encodings, which preserve global coherence until a measurement is performed. Contrasting this, we here demonstrate a distributed task based on a qubit channel, fo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.13495v2-abstract-full').style.display = 'inline'; document.getElementById('2306.13495v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.13495v2-abstract-full" style="display: none;"> Shared entanglement can significantly amplify classical correlations between systems interacting over a limited quantum channel. A natural avenue is to use entanglement of the same dimension as the channel because this allows for unitary encodings, which preserve global coherence until a measurement is performed. Contrasting this, we here demonstrate a distributed task based on a qubit channel, for which irreversible encoding operations can outperform any possible coherence-preserving protocol. This corresponds to using high-dimensional entanglement and encoding information by compressing one of the subsystems into a qubit. Demonstrating this phenomenon requires the preparation of a four-dimensional maximally entangled state, the compression of two qubits into one and joint qubit-ququart entangled measurements, with all modules executed at near-optimal fidelity. We report on a proof-of-principle experiment that achieves the advantage by realizing separate systems in distinct and independently controlled paths of a single photon. Our result demonstrates the relevance of high-dimensional entanglement and non-unitary operations for enhancing the communication capabilities of standard qubit transmissions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.13495v2-abstract-full').style.display = 'none'; document.getElementById('2306.13495v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 5 figures + appendix. Comments are welcome. V2: expanded and reformatted theory section, added experimental details</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.06912">arXiv:2306.06912</a> <span> [<a href="https://arxiv.org/pdf/2306.06912">pdf</a>, <a href="https://arxiv.org/format/2306.06912">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chaotic Dynamics">nlin.CD</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"> Chaos with Gaussian invariant distribution by quantum-noise random phase feedback </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanqiang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Haifeng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yingqi Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Meng%2C+X">Xiangyu Meng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+T">Tong Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiaomin Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.06912v1-abstract-short" style="display: inline;"> We experimentally present a random phase feedback based on quantum noise to generate a chaotic laser with Gaussian invariant distribution. The quantum noise from vacuum fluctuations is acquired by balanced homodyne detection and injected into a phase modulator to form a random phase feedback. An optical switch using high-speed intensity modulator is employed to reset the chaotic states repeatedly… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06912v1-abstract-full').style.display = 'inline'; document.getElementById('2306.06912v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.06912v1-abstract-full" style="display: none;"> We experimentally present a random phase feedback based on quantum noise to generate a chaotic laser with Gaussian invariant distribution. The quantum noise from vacuum fluctuations is acquired by balanced homodyne detection and injected into a phase modulator to form a random phase feedback. An optical switch using high-speed intensity modulator is employed to reset the chaotic states repeatedly and the time evolutions of intensity statistical distributions of the chaotic states stemming from the initial noise are measured. By the quantum-noise random phase feedback, the transient intensity distributions of the chaotic outputs are improved from asymmetric invariant distributions to Gaussian invariant distributions, and the Gaussian invariant distribution indicates a randomly perturbed dynamical transition from microscopic initial noise to macroscopic stochastic fluctuation. The effects of phase feedback bandwidth and modulation depth on the invariant distributions are investigated experimentally. The chaotic time-delay signature and mean permutation entropy are suppressed to 0.036 and enhanced to 0.999 using the random phase feedback, respectively. The high-quality chaotic laser with Gaussian invariant distribution can be a desired random source for ultrafast random number generation and secure communication. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06912v1-abstract-full').style.display = 'none'; document.getElementById('2306.06912v1-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 10 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.06556">arXiv:2306.06556</a> <span> [<a href="https://arxiv.org/pdf/2306.06556">pdf</a>, <a href="https://arxiv.org/format/2306.06556">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1367-2630/ace98d">10.1088/1367-2630/ace98d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Noise-induced dynamics and photon statistics in bimodal quantum-dot micropillar lasers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yanqiang Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jianfei Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+X">Xiaomin Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Reitzenstein%2C+S">Stephan Reitzenstein</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+L">Liantuan Xiao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.06556v2-abstract-short" style="display: inline;"> Emission characteristics of quantum-dot micropillar lasers (QDMLs) are located at the intersection of nanophotonics and nonlinear dynamics, which provides an ideal platform for studying the optical interface between classical and quantum systems. In this work, a noise-induced bimodal QDML with orthogonal dual-mode outputs is modeled, and nonlinear dynamics, stochastic mode jumping and quantum stat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06556v2-abstract-full').style.display = 'inline'; document.getElementById('2306.06556v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.06556v2-abstract-full" style="display: none;"> Emission characteristics of quantum-dot micropillar lasers (QDMLs) are located at the intersection of nanophotonics and nonlinear dynamics, which provides an ideal platform for studying the optical interface between classical and quantum systems. In this work, a noise-induced bimodal QDML with orthogonal dual-mode outputs is modeled, and nonlinear dynamics, stochastic mode jumping and quantum statistics with the variation of stochastic noise intensity are investigated. Noise-induced effects lead to the emergence of two intensity bifurcation points for the strong and the weak mode, and the maximum output power of the strong mode becomes larger as the noise intensity increases. The anti-correlation of the two modes reaches the maximum at the second intensity bifurcation point. The dual-mode stochastic jumping frequency and effective bandwidth can exceed 100 GHz and 30 GHz under the noise-induced effect. Moreover, the noise-induced photon correlations of both modes simultaneously exhibit super-thermal bunching effects ($g^{(2)}(0)>2$) in the low injection current region. The $g^{(2)}(0)$-value of the strong mode can reach over 6 in the high injection current region. Photon bunching ($g^{(2)}(0)>1$) of both modes is observed over a wide range of noise intensities and injection currents. In the presence of the noise-induced effect, the photon number distribution of the strong or the weak mode is a mixture of Bose-Einstein and Poisson distributions. As the noise intensity increases, the photon number distribution of the strong mode is dominated by the Bose-Einstein distribution, and the proportion of the Poisson distribution is increased in the high injection current region, while that of the weak mode is reduced. Our results contribute to the development preparation of super-bunching quantum integrated light sources for improving the spatiotemporal resolution of quantum sensing measurements. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06556v2-abstract-full').style.display = 'none'; document.getElementById('2306.06556v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.04851">arXiv:2306.04851</a> <span> [<a href="https://arxiv.org/pdf/2306.04851">pdf</a>, <a href="https://arxiv.org/format/2306.04851">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> The Performance of VQE across a phase transition point in the $J_1$-$J_2$ model on kagome lattice </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+M">Mingpu 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="2306.04851v1-abstract-short" style="display: inline;"> Variational quantum eigensolver (VQE) is an efficient classical-quantum hybrid method to take advantage of quantum computers in the Noisy Intermediate-Scale Quantum (NISQ) era. In this work we test the performance of VQE by studying the $J_1$-$J_2$ anti-ferromagnetic Heisenberg model on the kagome lattice, which is found to display a first order phase transition at $J_2 / J_1 \approx 0.01$. By com… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.04851v1-abstract-full').style.display = 'inline'; document.getElementById('2306.04851v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.04851v1-abstract-full" style="display: none;"> Variational quantum eigensolver (VQE) is an efficient classical-quantum hybrid method to take advantage of quantum computers in the Noisy Intermediate-Scale Quantum (NISQ) era. In this work we test the performance of VQE by studying the $J_1$-$J_2$ anti-ferromagnetic Heisenberg model on the kagome lattice, which is found to display a first order phase transition at $J_2 / J_1 \approx 0.01$. By comparing the VQE states with the exact diagonalization results, we find VQE energies agree well with the exact values in most region of parameters for the 18-site system we studied. However, near the phase transition point, VQE tends to converge to the excited states when the number of variational parameters is not large enough. For the system studied in this work, this issue can be solved by either increasing the number of parameters or by initializing the parameters with converged values for $J_2/J_1$ away from the phase transition point. Our results provide useful guidance for the practical application of VQE on real quantum computers to study strongly correlated quantum many-body systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.04851v1-abstract-full').style.display = 'none'; document.getElementById('2306.04851v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 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/2305.15992">arXiv:2305.15992</a> <span> [<a href="https://arxiv.org/pdf/2305.15992">pdf</a>, <a href="https://arxiv.org/ps/2305.15992">ps</a>, <a href="https://arxiv.org/format/2305.15992">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Theory">hep-th</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mathematical Physics">math-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/PhysRevD.108.125002">10.1103/PhysRevD.108.125002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Solving anharmonic oscillator with null states: Hamiltonian bootstrap and Dyson-Schwinger equations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yongwei Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wenliang 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="2305.15992v3-abstract-short" style="display: inline;"> As basic quantum mechanical models, anharmonic oscillators are recently revisited by bootstrap methods. An effective approach is to make use of the positivity constraints in Hermitian theories. There exists an alternative avenue based on the null state condition, which applies to both Hermitian and non-Hermitian theories. In this work, we carry out an analytic bootstrap study of the quartic oscill… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.15992v3-abstract-full').style.display = 'inline'; document.getElementById('2305.15992v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.15992v3-abstract-full" style="display: none;"> As basic quantum mechanical models, anharmonic oscillators are recently revisited by bootstrap methods. An effective approach is to make use of the positivity constraints in Hermitian theories. There exists an alternative avenue based on the null state condition, which applies to both Hermitian and non-Hermitian theories. In this work, we carry out an analytic bootstrap study of the quartic oscillator based on the small coupling expansion. In the Hamiltonian formalism, we obtain the anharmonic generalization of Dirac's ladder operators. Furthermore, the Schrodinger equation can be interpreted as a null state condition generated by an anharmonic ladder operator. This provides an explicit example in which dynamics is incorporated into the principle of nullness. In the Lagrangian formalism, we show that the existence of null states can effectively eliminate the indeterminacy of the Dyson-Schwinger equations and systematically determine $n$-point Green's functions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.15992v3-abstract-full').style.display = 'none'; document.getElementById('2305.15992v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 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">v3: 54 pages, typos corrected, references updated, discussions improved, Sec. 2.2 significantly expanded (high order results and comparison to the nonperturbative null bootstrap added)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.14231">arXiv:2305.14231</a> <span> [<a href="https://arxiv.org/pdf/2305.14231">pdf</a>, <a href="https://arxiv.org/format/2305.14231">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div 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.5.043069">10.1103/PhysRevResearch.5.043069 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Triggering Boundary Phase Transitions through Bulk Measurements in 2D Cluster States </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jian-Hao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Bi%2C+Z">Zhen Bi</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo 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="2305.14231v2-abstract-short" style="display: inline;"> We investigate the phase diagram at the boundary of an infinite two-dimensional cluster state subject to bulk measurements using tensor network methods. The state is subjected to uniform measurements $M = \cos胃Z+\sin胃X$ on the lower boundary qubits and in all bulk qubits. Our results show that the boundary of the system exhibits volume-law entanglement at the measurement angle $胃= 蟺/2$ and area-la… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.14231v2-abstract-full').style.display = 'inline'; document.getElementById('2305.14231v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.14231v2-abstract-full" style="display: none;"> We investigate the phase diagram at the boundary of an infinite two-dimensional cluster state subject to bulk measurements using tensor network methods. The state is subjected to uniform measurements $M = \cos胃Z+\sin胃X$ on the lower boundary qubits and in all bulk qubits. Our results show that the boundary of the system exhibits volume-law entanglement at the measurement angle $胃= 蟺/2$ and area-law entanglement for any $胃< 蟺/2$. Within the area-law phase, a phase transition occurs at $胃_c=1.371$. The phase with $胃\in(胃_c,蟺/2)$ is characterized by a noninjective matrix product state, which cannot be realized as the unique ground state of a one-dimensional local, gapped Hamiltonian. Instead, it resembles a cat state with spontaneous symmetry breaking. These findings demonstrate that the phase diagram of the boundary of a two-dimensional system can be more intricate than that of a standard one-dimensional system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.14231v2-abstract-full').style.display = 'none'; document.getElementById('2305.14231v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 5, 043069 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.09960">arXiv:2305.09960</a> <span> [<a href="https://arxiv.org/pdf/2305.09960">pdf</a>, <a href="https://arxiv.org/ps/2305.09960">ps</a>, <a href="https://arxiv.org/format/2305.09960">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"> Scattering of one-dimensional quantum droplets by a reflectionless potential well </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiaoxiao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zhiqiang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yajiang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+X">Xiaobing Luo</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="2305.09960v1-abstract-short" style="display: inline;"> We investigate, both analytically and numerically, the scattering of one-dimensional quantum droplets by a P枚schl-Teller reflectionless potential well, confirming that there is a sharp transition between full reflection and full transmission at a certain critical incident speed for both small droplets and large flat-top droplets. We observe sharp differences between small quantum droplet scatterin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.09960v1-abstract-full').style.display = 'inline'; document.getElementById('2305.09960v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.09960v1-abstract-full" style="display: none;"> We investigate, both analytically and numerically, the scattering of one-dimensional quantum droplets by a P枚schl-Teller reflectionless potential well, confirming that there is a sharp transition between full reflection and full transmission at a certain critical incident speed for both small droplets and large flat-top droplets. We observe sharp differences between small quantum droplet scattering and large quantum droplet scattering. The scattering of small quantum droplets is similar to that of solitons, where a spatially symmetric trapped mode is formed at the critical speed, whereas for large quantum droplets a spatially asymmetric trapped mode is formed. Additionally, a nonmonotonous dependence of the critical speed on the atom number is identified$:$ on the small-droplet side, the critical speed increases with the atom number, while in the flat-top regime, the critical speed decreases with increasing the atom number. Strikingly, the scattering excites internal modes below the particle-emission threshold, preventing the quantum droplets from emitting radiation upon interaction with the potential. Analysis of the small-amplitude excitation spectrum shows that as the number of particles increases, it becomes increasingly difficult to emit particles outside the droplet during scattering, while radiation from solitons cannot be completely avoided. Finally, we study the collision of two quantum droplets at the reflectionless potential, revealing the role of the $蟺$-phase difference ``generator'' played by the reflectionless potential. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.09960v1-abstract-full').style.display = 'none'; document.getElementById('2305.09960v1-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 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">14pages,13 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.13589">arXiv:2304.13589</a> <span> [<a href="https://arxiv.org/pdf/2304.13589">pdf</a>, <a href="https://arxiv.org/format/2304.13589">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"> Strong dispersive coupling between a mechanical resonator and a fluxonium superconducting qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lee%2C+N+R+A">Nathan R. A. Lee</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yudan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Cleland%2C+A+Y">Agnetta Y. Cleland</a>, <a href="/search/quant-ph?searchtype=author&query=Wollack%2C+E+A">E. Alex Wollack</a>, <a href="/search/quant-ph?searchtype=author&query=Gruenke%2C+R+G">Rachel G. Gruenke</a>, <a href="/search/quant-ph?searchtype=author&query=Makihara%2C+T">Takuma Makihara</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhaoyou Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Rajabzadeh%2C+T">Taha Rajabzadeh</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+W">Wentao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Mayor%2C+F+M">Felix M. Mayor</a>, <a href="/search/quant-ph?searchtype=author&query=Arrangoiz-Arriola%2C+P">Patricio Arrangoiz-Arriola</a>, <a href="/search/quant-ph?searchtype=author&query=Sarabalis%2C+C+J">Christopher J. Sarabalis</a>, <a href="/search/quant-ph?searchtype=author&query=Safavi-Naeini%2C+A+H">Amir H. Safavi-Naeini</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="2304.13589v1-abstract-short" style="display: inline;"> We demonstrate strong dispersive coupling between a fluxonium superconducting qubit and a 690 megahertz mechanical oscillator, extending the reach of circuit quantum acousto-dynamics (cQAD) experiments into a new range of frequencies. We have engineered a qubit-phonon coupling rate of $g\approx2蟺\times14~\text{MHz}$, and achieved a dispersive interaction that exceeds the decoherence rates of both… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13589v1-abstract-full').style.display = 'inline'; document.getElementById('2304.13589v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.13589v1-abstract-full" style="display: none;"> We demonstrate strong dispersive coupling between a fluxonium superconducting qubit and a 690 megahertz mechanical oscillator, extending the reach of circuit quantum acousto-dynamics (cQAD) experiments into a new range of frequencies. We have engineered a qubit-phonon coupling rate of $g\approx2蟺\times14~\text{MHz}$, and achieved a dispersive interaction that exceeds the decoherence rates of both systems while the qubit and mechanics are highly nonresonant ($螖/g\gtrsim10$). Leveraging this strong coupling, we perform phonon number-resolved measurements of the mechanical resonator and investigate its dissipation and dephasing properties. Our results demonstrate the potential for fluxonium-based hybrid quantum systems, and a path for developing new quantum sensing and information processing schemes with phonons at frequencies below 700 MHz to significantly expand the toolbox of cQAD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13589v1-abstract-full').style.display = 'none'; document.getElementById('2304.13589v1-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 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">22 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/2304.12813">arXiv:2304.12813</a> <span> [<a href="https://arxiv.org/pdf/2304.12813">pdf</a>, <a href="https://arxiv.org/format/2304.12813">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/OE.494850">10.1364/OE.494850 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Preparation of multiphoton high-dimensional GHZ state </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xing%2C+W">Wen-Bo Xing</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Min Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.12813v4-abstract-short" style="display: inline;"> Multipartite high-dimensional entanglement presents different physics from multipartite two-dimensional entanglement. However, how to prepare multipartite high-dimensional entanglement is still a challenge with linear optics. In this paper, a multiphoton GHZ state with arbitrary dimensions preparation protocol is proposed in optical systems. In this protocol, we use auxiliary entanglements to real… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.12813v4-abstract-full').style.display = 'inline'; document.getElementById('2304.12813v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.12813v4-abstract-full" style="display: none;"> Multipartite high-dimensional entanglement presents different physics from multipartite two-dimensional entanglement. However, how to prepare multipartite high-dimensional entanglement is still a challenge with linear optics. In this paper, a multiphoton GHZ state with arbitrary dimensions preparation protocol is proposed in optical systems. In this protocol, we use auxiliary entanglements to realize a high-dimensional entanglement gate, so that high-dimensional entangled pairs can be connected into a multipartite high-dimensional GHZ state. Specifically, we give an example of using photons' path degree of freedom to prepare a 4-particle 3-dimensional GHZ state. Our method can be extended to other degrees of freedom and can generate arbitrary GHZ entanglement in any dimension. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.12813v4-abstract-full').style.display = 'none'; document.getElementById('2304.12813v4-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 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">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> Opt. Express 31, 24887-24896 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.04588">arXiv:2304.04588</a> <span> [<a href="https://arxiv.org/pdf/2304.04588">pdf</a>, <a href="https://arxiv.org/format/2304.04588">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevResearch.5.033181">10.1103/PhysRevResearch.5.033181 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Composite Quantum Phases in Non-Hermitian Systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yuchen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+R">Ruohan Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo 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="2304.04588v2-abstract-short" style="display: inline;"> Non-Hermitian systems have attracted considerable interest in recent years owing to their unique topological properties that are absent in Hermitian systems. While such properties have been thoroughly characterized in free fermion models, they remain an open question for interacting bosonic systems. In this work, we present a precise definition of quantum phases for non-Hermitian systems and propo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.04588v2-abstract-full').style.display = 'inline'; document.getElementById('2304.04588v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.04588v2-abstract-full" style="display: none;"> Non-Hermitian systems have attracted considerable interest in recent years owing to their unique topological properties that are absent in Hermitian systems. While such properties have been thoroughly characterized in free fermion models, they remain an open question for interacting bosonic systems. In this work, we present a precise definition of quantum phases for non-Hermitian systems and propose a new family of phases referred to as composite quantum phases. We demonstrate the existence of these phases in a one-dimensional spin-$1$ system and show their robustness against perturbations through numerical simulations. Furthermore, we investigate the phase diagram of our model, indicating the extensive presence of these new phases in non-Hermitian systems. Our work establishes a new framework for studying and constructing quantum phases in non-Hermitian interacting systems, revealing exciting possibilities beyond the single-particle picture. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.04588v2-abstract-full').style.display = 'none'; document.getElementById('2304.04588v2-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 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">9 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 5, 033181 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.17223">arXiv:2303.17223</a> <span> [<a href="https://arxiv.org/pdf/2303.17223">pdf</a>, <a href="https://arxiv.org/format/2303.17223">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"> Experimental super-Heisenberg quantum metrology with indefinite gate order </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yin%2C+P">Peng Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+X">Xiaobin Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+Y">Yuxiang Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yu Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wen-Hao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Gong-Chu Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Y">Yong-Jian Han</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+B">Bi-Heng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jin-Shi Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Chiribella%2C+G">Giulio Chiribella</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+G">Geng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.17223v1-abstract-short" style="display: inline;"> The precision of quantum metrology is widely believed to be restricted by the Heisenberg limit, corresponding to a root mean square error that is inversely proportional to the number of independent processes probed in an experiment, N. In the past, some proposals have challenged this belief, for example using non-linear interactions among the probes. However, these proposals turned out to still ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.17223v1-abstract-full').style.display = 'inline'; document.getElementById('2303.17223v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.17223v1-abstract-full" style="display: none;"> The precision of quantum metrology is widely believed to be restricted by the Heisenberg limit, corresponding to a root mean square error that is inversely proportional to the number of independent processes probed in an experiment, N. In the past, some proposals have challenged this belief, for example using non-linear interactions among the probes. However, these proposals turned out to still obey the Heisenberg limit with respect to other relevant resources, such as the total energy of the probes. Here, we present a photonic implementation of a quantum metrology protocol surpassing the Heisenberg limit by probing two groups of independent processes in a superposition of two alternative causal orders. Each process creates a phase space displacement, and our setup is able to estimate a geometric phase associated to two sets of N displacements with an error that falls quadratically with N. Our results only require a single-photon probe with an initial energy that is independent of N. Using a superposition of causal orders outperforms every setup where the displacements are probed in a definite order. Our experiment features the demonstration of indefinite causal order in a continuous-variable system, and opens up the experimental investigation of quantum metrology setups boosted by indefinite causal order. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.17223v1-abstract-full').style.display = 'none'; document.getElementById('2303.17223v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.12355">arXiv:2303.12355</a> <span> [<a href="https://arxiv.org/pdf/2303.12355">pdf</a>, <a href="https://arxiv.org/format/2303.12355">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.21.014026">10.1103/PhysRevApplied.21.014026 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Security boundaries of an optical power limiter for protecting quantum key distribution systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Peng%2C+Q">Qingquan Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+B">Binwu Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Zaitsev%2C+K">Konstantin Zaitsev</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+D">Dongyang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ding%2C+J">Jiangfang Ding</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yingwen Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+Q">Qin Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Ying Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+A">Anqi Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Junjie 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="2303.12355v3-abstract-short" style="display: inline;"> Unauthorized light injection has always been a vital threat to the practical security of a quantum key distribution (QKD) system. An optical power limiter (OPL) based on the thermo-optical defocusing effect has been proposed and implemented, limiting the injected hacking light. As a hardware countermeasure, the performance of the OPL under various light-injection attacks shall be tested to clarify… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12355v3-abstract-full').style.display = 'inline'; document.getElementById('2303.12355v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.12355v3-abstract-full" style="display: none;"> Unauthorized light injection has always been a vital threat to the practical security of a quantum key distribution (QKD) system. An optical power limiter (OPL) based on the thermo-optical defocusing effect has been proposed and implemented, limiting the injected hacking light. As a hardware countermeasure, the performance of the OPL under various light-injection attacks shall be tested to clarify the security boundary before being widely deployed. To investigate the OPL's security boundary in quantum cryptography, we comprehensively test and analyse the behavior of OPL under continuous-wave (c.w.) light-injection attacks and pulse illumination attacks with pulses' repetition rate at $0.5$-$\hertz$, $40$-$\mega\hertz$, and $1$-$\giga\hertz$. The testing results illuminate the security boundary of the OPL, which allows one to properly employ the OPL in the use cases. The methodology of testing and analysis proposed here is applicable to other power-limitation components in a QKD system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12355v3-abstract-full').style.display = 'none'; document.getElementById('2303.12355v3-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 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">15 pages, 14 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/2303.09636">arXiv:2303.09636</a> <span> [<a href="https://arxiv.org/pdf/2303.09636">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="Chemical Physics">physics.chem-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/10.1021/acsnano.3c01819">10.1021/acsnano.3c01819 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nitrogen-vacancy magnetometry of individual Fe-triazole spin crossover nanorods </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lamichhane%2C+S">Suvechhya Lamichhane</a>, <a href="/search/quant-ph?searchtype=author&query=McElveen%2C+K+A">Kayleigh A McElveen</a>, <a href="/search/quant-ph?searchtype=author&query=Erickson%2C+A">Adam Erickson</a>, <a href="/search/quant-ph?searchtype=author&query=Fescenko%2C+I">Ilja Fescenko</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shuo Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Timalsina%2C+R">Rupak Timalsina</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Y">Yinsheng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Liou%2C+S">Sy-Hwang Liou</a>, <a href="/search/quant-ph?searchtype=author&query=Lai%2C+R+Y">Rebecca Y. Lai</a>, <a href="/search/quant-ph?searchtype=author&query=Laraoui%2C+A">Abdelghani Laraoui</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="2303.09636v4-abstract-short" style="display: inline;"> [Fe(Htrz)2(trz)](BF4) (Fe-triazole) spin crossover molecules show thermal, electrical, and optical switching between high spin (HS) and low spin (LS) states, making them promising candidates for molecular spintronics. The LS and HS transitions originate from the electronic configurations of Fe(II), and are considered to be diamagnetic and paramagnetic respectively. The Fe(II) LS state has six pair… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.09636v4-abstract-full').style.display = 'inline'; document.getElementById('2303.09636v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.09636v4-abstract-full" style="display: none;"> [Fe(Htrz)2(trz)](BF4) (Fe-triazole) spin crossover molecules show thermal, electrical, and optical switching between high spin (HS) and low spin (LS) states, making them promising candidates for molecular spintronics. The LS and HS transitions originate from the electronic configurations of Fe(II), and are considered to be diamagnetic and paramagnetic respectively. The Fe(II) LS state has six paired electrons in the ground states with no interaction with the magnetic field and a diamagnetic behavior is usually observed. While the bulk magnetic properties of Fe-triazole compounds are widely studied by standard magnetometry techniques their properties at the individual level are missing. Here we use nitrogen vacancy (NV) based magnetometry to study the magnetic properties of the Fe-triazole LS state of nanoparticle clusters and individual nanorods of size varying from 20 to 1000 nm. Scanning electron microscopy (SEM) and Raman spectroscopy are performed to determine the size of the nanoparticles/nanorods and to confirm their respective spin state. The magnetic field patterns produced by the nanoparticles/nanorods are imaged by NV magnetic microscopy as a function of applied magnetic field (up to 350 mT) and correlated with SEM and Raman. We found that in most of the nanorods the LS state is slightly paramagnetic, possibly originating from the surface oxidation and/or the greater Fe(III) presence along the nanorod edges. NV measurements on the Fe-triazole LS state nanoparticle clusters revealed both diamagnetic and paramagnetic behavior. Our results highlight the potential of NV quantum sensors to study the magnetic properties of spin crossover molecules and molecular magnets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.09636v4-abstract-full').style.display = 'none'; document.getElementById('2303.09636v4-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 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">Journal ref:</span> ACS Nano 2023 </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous 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