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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <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/2412.20893">arXiv:2412.20893</a> <span> [<a href="https://arxiv.org/pdf/2412.20893">pdf</a>, <a href="https://arxiv.org/format/2412.20893">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"> Redesign Quantum Circuits on Quantum Hardware Device </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=He%2C+R">Runhong He</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+X">Xin Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+X">Xusheng Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+G">Guolong Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shengbin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+S">Shenggang Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2412.20893v1-abstract-short" style="display: inline;"> In the process of exploring quantum algorithms, researchers often need to conduct equivalence checking of quantum circuits with different structures or to reconstruct a circuit in a variational manner, aiming to reduce the depth of the target circuit. Whereas the exponential resource overhead for describing quantum systems classically makes the existing methods not amenable to serving large-scale… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.20893v1-abstract-full').style.display = 'inline'; document.getElementById('2412.20893v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.20893v1-abstract-full" style="display: none;"> In the process of exploring quantum algorithms, researchers often need to conduct equivalence checking of quantum circuits with different structures or to reconstruct a circuit in a variational manner, aiming to reduce the depth of the target circuit. Whereas the exponential resource overhead for describing quantum systems classically makes the existing methods not amenable to serving large-scale quantum circuits. Grounded in the entangling quantum generative adversarial network (EQ-GAN), we present in this article a new architecture which enables one to redesign large-scale quantum circuits on quantum hardware. For concreteness, we apply this architecture to three crucial applications in circuit optimization, including the equivalence checking of (non-) parameterized circuits, as well as the variational reconstruction of quantum circuits. The feasibility of our approach is demonstrated by the excellent results of these applications, which are implemented both in classical computers and current NISQ hardware. We believe our work should facilitate the implementation and validation of the advantages of quantum algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.20893v1-abstract-full').style.display = 'none'; document.getElementById('2412.20893v1-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 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">9 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/2412.05542">arXiv:2412.05542</a> <span> [<a href="https://arxiv.org/pdf/2412.05542">pdf</a>, <a href="https://arxiv.org/format/2412.05542">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="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> <span class="tag is-small is-grey 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="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> 113 km absolute ranging with nanometer precision </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yan-Wei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Lian%2C+M">Meng-Zhe Lian</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+J">Jin-Jian Han</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+T">Ting Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Min Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+G">Guo-Dong Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Sheng%2C+Y">Yi Sheng</a>, <a href="/search/quant-ph?searchtype=author&query=Esamdin%2C+A">Ali Esamdin</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+L">Lei Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+Q">Qi Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+J">Jian-Jun Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+J">Ji-Gang Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+H">Hai-Feng Jiang</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="2412.05542v1-abstract-short" style="display: inline;"> Accurate long-distance ranging is crucial for diverse applications, including satellite formation flying, very-long-baseline interferometry, gravitational-wave observatory, geographical research, etc. The integration of the time-of-flight mesurement with phase interference in dual-comb method enables high-precision ranging with a rapid update rate and an extended ambiguity range. Pioneering experi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.05542v1-abstract-full').style.display = 'inline'; document.getElementById('2412.05542v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.05542v1-abstract-full" style="display: none;"> Accurate long-distance ranging is crucial for diverse applications, including satellite formation flying, very-long-baseline interferometry, gravitational-wave observatory, geographical research, etc. The integration of the time-of-flight mesurement with phase interference in dual-comb method enables high-precision ranging with a rapid update rate and an extended ambiguity range. Pioneering experiments have demonstrated unprecedented precision in ranging, achieving 5 nm @ 60 ms for 1.1 m and 200 nm @ 0.5 s for 25 m. However, long-distance ranging remains technically challenging due to high transmission loss and noise. In this letter, we propose a two-way dual-comb ranging (TWDCR) approach that enables successful ranging over a distance of 113 kilometers. We employ air dispersion analysis and synthetic repetition rate technique to extend the ambiguity range of the inherently noisy channel beyond 100 km. The achieved ranging precision is 11.5 $渭$m @ 1.3 ms, 681 nm @ 1 s, and 82 nm @ 21 s, as confirmed through a comparative analysis of two independent systems. The advanced long-distance ranging technology is expected to have immediate implications for space research initiatives, such as the space telescope array and the satellite gravimetry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.05542v1-abstract-full').style.display = 'none'; document.getElementById('2412.05542v1-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 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">21 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/2407.13533">arXiv:2407.13533</a> <span> [<a href="https://arxiv.org/pdf/2407.13533">pdf</a>, <a href="https://arxiv.org/format/2407.13533">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"> VeriQR: A Robustness Verification Tool for Quantum Machine Learning Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Y">Yanling Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+Z">Zhaofeng Su</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="2407.13533v1-abstract-short" style="display: inline;"> Adversarial noise attacks present a significant threat to quantum machine learning (QML) models, similar to their classical counterparts. This is especially true in the current Noisy Intermediate-Scale Quantum era, where noise is unavoidable. Therefore, it is essential to ensure the robustness of QML models before their deployment. To address this challenge, we introduce \textit{VeriQR}, the first… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.13533v1-abstract-full').style.display = 'inline'; document.getElementById('2407.13533v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.13533v1-abstract-full" style="display: none;"> Adversarial noise attacks present a significant threat to quantum machine learning (QML) models, similar to their classical counterparts. This is especially true in the current Noisy Intermediate-Scale Quantum era, where noise is unavoidable. Therefore, it is essential to ensure the robustness of QML models before their deployment. To address this challenge, we introduce \textit{VeriQR}, the first tool designed specifically for formally verifying and improving the robustness of QML models, to the best of our knowledge. This tool mimics real-world quantum hardware's noisy impacts by incorporating random noise to formally validate a QML model's robustness. \textit{VeriQR} supports exact (sound and complete) algorithms for both local and global robustness verification. For enhanced efficiency, it implements an under-approximate (complete) algorithm and a tensor network-based algorithm to verify local and global robustness, respectively. As a formal verification tool, \textit{VeriQR} can detect adversarial examples and utilize them for further analysis and to enhance the local robustness through adversarial training, as demonstrated by experiments on real-world quantum machine learning models. Moreover, it permits users to incorporate customized noise. Based on this feature, we assess \textit{VeriQR} using various real-world examples, and experimental outcomes confirm that the addition of specific quantum noise can enhance the global robustness of QML models. These processes are made accessible through a user-friendly graphical interface provided by \textit{VeriQR}, catering to general users without requiring a deep understanding of the counter-intuitive probabilistic nature of quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.13533v1-abstract-full').style.display = 'none'; document.getElementById('2407.13533v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 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/2407.13516">arXiv:2407.13516</a> <span> [<a href="https://arxiv.org/pdf/2407.13516">pdf</a>, <a href="https://arxiv.org/format/2407.13516">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"> Optimal Mechanisms for Quantum Local Differential Privacy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</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="2407.13516v2-abstract-short" style="display: inline;"> The exploration of the quantum local differential privacy (QLDP) framework is still in its early stages, primarily conceptual, which poses challenges for its practical implementation in safeguarding quantum state privacy. This paper initiates a comprehensive algorithmic exploration of QLDP to establish a practical and viable QLDP framework for safeguarding quantum state privacy. QLDP utilizes a pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.13516v2-abstract-full').style.display = 'inline'; document.getElementById('2407.13516v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.13516v2-abstract-full" style="display: none;"> The exploration of the quantum local differential privacy (QLDP) framework is still in its early stages, primarily conceptual, which poses challenges for its practical implementation in safeguarding quantum state privacy. This paper initiates a comprehensive algorithmic exploration of QLDP to establish a practical and viable QLDP framework for safeguarding quantum state privacy. QLDP utilizes a parameter $蔚$ to manage privacy leaks and ensure the privacy of individual quantum states. The optimization of the QLDP value $蔚$, denoted as $蔚^*$, for any quantum mechanism is addressed as an optimization problem. The introduction of quantum noise is shown to provide privacy protections similar to classical scenarios, with quantum depolarizing noise identified as the optimal unital privatization mechanism within the QLDP framework. Unital mechanisms represent a diverse set of quantum mechanisms that encompass frequently employed quantum noise types. Quantum depolarizing noise optimizes both fidelity and trace distance utilities, which are crucial metrics in the field of quantum computation and information, and can be viewed as a quantum counterpart to classical randomized response methods. Furthermore, a composition theorem is presented for the application of QLDP framework in distributed (spatially separated) quantum systems, ensuring the validity (additivity of QLDP value) irrespective of the states' independence, classical correlation, or entanglement (quantum correlation). The study further explores the trade-off between utility and privacy across different quantum noise mechanisms, including unital and non-unital quantum noise mechanisms, through both analytical and numerically experimental approaches. Meanwhile, this highlights the optimization of quantum depolarizing noise in QLDP framework. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.13516v2-abstract-full').style.display = 'none'; document.getElementById('2407.13516v2-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">v1</span> submitted 18 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/2405.05825">arXiv:2405.05825</a> <span> [<a href="https://arxiv.org/pdf/2405.05825">pdf</a>, <a href="https://arxiv.org/format/2405.05825">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Measurement-based Verification of Quantum Markov Chains </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+Y">Yuan Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Turrini%2C+A">Andrea Turrini</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.05825v1-abstract-short" style="display: inline;"> Model-checking techniques have been extended to analyze quantum programs and communication protocols represented as quantum Markov chains, an extension of classical Markov chains. To specify qualitative temporal properties, a subspace-based quantum temporal logic is used, which is built on Birkhoff-von Neumann atomic propositions. These propositions determine whether a quantum state is within a su… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05825v1-abstract-full').style.display = 'inline'; document.getElementById('2405.05825v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.05825v1-abstract-full" style="display: none;"> Model-checking techniques have been extended to analyze quantum programs and communication protocols represented as quantum Markov chains, an extension of classical Markov chains. To specify qualitative temporal properties, a subspace-based quantum temporal logic is used, which is built on Birkhoff-von Neumann atomic propositions. These propositions determine whether a quantum state is within a subspace of the entire state space. In this paper, we propose the measurement-based linear-time temporal logic MLTL to check quantitative properties. MLTL builds upon classical linear-time temporal logic (LTL) but introduces quantum atomic propositions that reason about the probability distribution after measuring a quantum state. To facilitate verification, we extend the symbolic dynamics-based techniques for stochastic matrices described by Agrawal et al. (JACM 2015) to handle more general quantum linear operators (super-operators) through eigenvalue analysis. This extension enables the development of an efficient algorithm for approximately model checking a quantum Markov chain against an MLTL formula. To demonstrate the utility of our model-checking algorithm, we use it to simultaneously verify linear-time properties of both quantum and classical random walks. Through this verification, we confirm the previously established advantages discovered by Ambainis et al. (STOC 2001) of quantum walks over classical random walks and discover new phenomena unique to quantum walks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.05825v1-abstract-full').style.display = 'none'; document.getElementById('2405.05825v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.19294">arXiv:2310.19294</a> <span> [<a href="https://arxiv.org/pdf/2310.19294">pdf</a>, <a href="https://arxiv.org/format/2310.19294">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dual-comb spectroscopy over 100km open-air path </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Han%2C+J">Jin-Jian Han</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+W">Wei Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+R">Ruo-Can Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+T">Ting Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Min Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+J">Jian Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+X">Xin-Xin Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+X">Xi-Ping Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+Q">Qin Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Esamdin%2C+A">Ali Esamdin</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+Q">Qi Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Hou%2C+L">Lei Hou</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+J">Ji-Gang Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+J">Jian-Jun Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">Yu Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+H">Hai-Feng Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+X">XiangHui Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Dou%2C+X">Xian-Kang Dou</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="2310.19294v2-abstract-short" style="display: inline;"> Satellite-based greenhouse gases (GHG) sensing technologies play a critical role in the study of global carbon emissions and climate change. However, none of the existing satellite-based GHG sensing technologies can achieve the measurement of broad bandwidth, high temporal-spatial resolution, and high sensitivity at the same time. Recently, dual-comb spectroscopy (DCS) has been proposed as a super… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.19294v2-abstract-full').style.display = 'inline'; document.getElementById('2310.19294v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.19294v2-abstract-full" style="display: none;"> Satellite-based greenhouse gases (GHG) sensing technologies play a critical role in the study of global carbon emissions and climate change. However, none of the existing satellite-based GHG sensing technologies can achieve the measurement of broad bandwidth, high temporal-spatial resolution, and high sensitivity at the same time. Recently, dual-comb spectroscopy (DCS) has been proposed as a superior candidate technology for GHG sensing because it can measure broadband spectra with high temporal-spatial resolution and high sensitivity. The main barrier to DCS's display on satellites is its short measurement distance in open air achieved thus far. Prior research has not been able to implement DCS over 20 km of open-air path. Here, by developing a bistatic setup using time-frequency dissemination and high-power optical frequency combs, we have implemented DCS over a 113 km turbulent horizontal open-air path. Our experiment successfully measured GHG with 7 nm spectral bandwidth and a 10 kHz frequency and achieved a CO2 sensing precision of <2 ppm in 5 minutes and <0.6 ppm in 36 minutes. Our results represent a significant step towards advancing the implementation of DCS as a satellite-based technology and improving technologies for GHG monitoring <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.19294v2-abstract-full').style.display = 'none'; document.getElementById('2310.19294v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 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">24 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/2309.04819">arXiv:2309.04819</a> <span> [<a href="https://arxiv.org/pdf/2309.04819">pdf</a>, <a href="https://arxiv.org/format/2309.04819">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cryptography and Security">cs.CR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1145/3576915.3623108">10.1145/3576915.3623108 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detecting Violations of Differential Privacy for Quantum Algorithms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+M">Mingyu Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2309.04819v1-abstract-short" style="display: inline;"> Quantum algorithms for solving a wide range of practical problems have been proposed in the last ten years, such as data search and analysis, product recommendation, and credit scoring. The concern about privacy and other ethical issues in quantum computing naturally rises up. In this paper, we define a formal framework for detecting violations of differential privacy for quantum algorithms. A det… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.04819v1-abstract-full').style.display = 'inline'; document.getElementById('2309.04819v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.04819v1-abstract-full" style="display: none;"> Quantum algorithms for solving a wide range of practical problems have been proposed in the last ten years, such as data search and analysis, product recommendation, and credit scoring. The concern about privacy and other ethical issues in quantum computing naturally rises up. In this paper, we define a formal framework for detecting violations of differential privacy for quantum algorithms. A detection algorithm is developed to verify whether a (noisy) quantum algorithm is differentially private and automatically generate bugging information when the violation of differential privacy is reported. The information consists of a pair of quantum states that violate the privacy, to illustrate the cause of the violation. Our algorithm is equipped with Tensor Networks, a highly efficient data structure, and executed both on TensorFlow Quantum and TorchQuantum which are the quantum extensions of famous machine learning platforms -- TensorFlow and PyTorch, respectively. The effectiveness and efficiency of our algorithm are confirmed by the experimental results of almost all types of quantum algorithms already implemented on realistic quantum computers, including quantum supremacy algorithms (beyond the capability of classical algorithms), quantum machine learning models, quantum approximate optimization algorithms, and variational quantum eigensolvers with up to 21 quantum bits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.04819v1-abstract-full').style.display = 'none'; document.getElementById('2309.04819v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> In Proceedings of the 2023 ACM SIGSAC Conference on Computer and Communications Security (CCS 2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.01999">arXiv:2308.01999</a> <span> [<a href="https://arxiv.org/pdf/2308.01999">pdf</a>, <a href="https://arxiv.org/format/2308.01999">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="Performance">cs.PF</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Software Engineering">cs.SE</span> </div> </div> <p class="title is-5 mathjax"> cuQuantum SDK: A High-Performance Library for Accelerating Quantum Science </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Bayraktar%2C+H">Harun Bayraktar</a>, <a href="/search/quant-ph?searchtype=author&query=Charara%2C+A">Ali Charara</a>, <a href="/search/quant-ph?searchtype=author&query=Clark%2C+D">David Clark</a>, <a href="/search/quant-ph?searchtype=author&query=Cohen%2C+S">Saul Cohen</a>, <a href="/search/quant-ph?searchtype=author&query=Costa%2C+T">Timothy Costa</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+Y+L">Yao-Lung L. Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+Y">Yang Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jack Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Gunnels%2C+J">John Gunnels</a>, <a href="/search/quant-ph?searchtype=author&query=Haidar%2C+A">Azzam Haidar</a>, <a href="/search/quant-ph?searchtype=author&query=Hehn%2C+A">Andreas Hehn</a>, <a href="/search/quant-ph?searchtype=author&query=Hohnerbach%2C+M">Markus Hohnerbach</a>, <a href="/search/quant-ph?searchtype=author&query=Jones%2C+M">Matthew Jones</a>, <a href="/search/quant-ph?searchtype=author&query=Lubowe%2C+T">Tom Lubowe</a>, <a href="/search/quant-ph?searchtype=author&query=Lyakh%2C+D">Dmitry Lyakh</a>, <a href="/search/quant-ph?searchtype=author&query=Morino%2C+S">Shinya Morino</a>, <a href="/search/quant-ph?searchtype=author&query=Springer%2C+P">Paul Springer</a>, <a href="/search/quant-ph?searchtype=author&query=Stanwyck%2C+S">Sam Stanwyck</a>, <a href="/search/quant-ph?searchtype=author&query=Terentyev%2C+I">Igor Terentyev</a>, <a href="/search/quant-ph?searchtype=author&query=Varadhan%2C+S">Satya Varadhan</a>, <a href="/search/quant-ph?searchtype=author&query=Wong%2C+J">Jonathan Wong</a>, <a href="/search/quant-ph?searchtype=author&query=Yamaguchi%2C+T">Takuma Yamaguchi</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.01999v1-abstract-short" style="display: inline;"> We present the NVIDIA cuQuantum SDK, a state-of-the-art library of composable primitives for GPU-accelerated quantum circuit simulations. As the size of quantum devices continues to increase, making their classical simulation progressively more difficult, the availability of fast and scalable quantum circuit simulators becomes vital for quantum algorithm developers, as well as quantum hardware eng… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.01999v1-abstract-full').style.display = 'inline'; document.getElementById('2308.01999v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.01999v1-abstract-full" style="display: none;"> We present the NVIDIA cuQuantum SDK, a state-of-the-art library of composable primitives for GPU-accelerated quantum circuit simulations. As the size of quantum devices continues to increase, making their classical simulation progressively more difficult, the availability of fast and scalable quantum circuit simulators becomes vital for quantum algorithm developers, as well as quantum hardware engineers focused on the validation and optimization of quantum devices. The cuQuantum SDK was created to accelerate and scale up quantum circuit simulators developed by the quantum information science community by enabling them to utilize efficient scalable software building blocks optimized for NVIDIA GPU platforms. The functional building blocks provided cover the needs of both state vector- and tensor network- based simulators, including approximate tensor network simulation methods based on matrix product state, projected entangled pair state, and other factorized tensor representations. By leveraging the enormous computing power of the latest NVIDIA GPU architectures, quantum circuit simulators that have adopted the cuQuantum SDK demonstrate significant acceleration, compared to CPU-only execution, for both the state vector and tensor network simulation methods. Furthermore, by utilizing the parallel primitives available in the cuQuantum SDK, one can easily transition to distributed GPU-accelerated platforms, including those furnished by cloud service providers and high-performance computing systems deployed by supercomputing centers, extending the scale of possible quantum circuit simulations. The rich capabilities provided by the SDK are conveniently made available via both Python and C application programming interfaces, where the former is directly targeting a broad Python quantum community and the latter allows tight integration with simulators written in any programming language. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.01999v1-abstract-full').style.display = 'none'; document.getElementById('2308.01999v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">paper accepted at QCE 2023, journal reference will be updated whenever available</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 68Q12; 68Q09; 81P68; </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.17028">arXiv:2211.17028</a> <span> [<a href="https://arxiv.org/pdf/2211.17028">pdf</a>, <a href="https://arxiv.org/ps/2211.17028">ps</a>, <a href="https://arxiv.org/format/2211.17028">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"> Approximation Algorithm for Noisy Quantum Circuit Simulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+M">Mingyu Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.17028v2-abstract-short" style="display: inline;"> Simulating noisy quantum circuits is vital in designing and verifying quantum algorithms in the current NISQ (Noisy Intermediate-Scale Quantum) era, where quantum noise is unavoidable. However, it is much more inefficient than the classical counterpart because of the quantum state explosion problem (the dimension of state space is exponential in the number of qubits) and the complex (non-unitary)… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.17028v2-abstract-full').style.display = 'inline'; document.getElementById('2211.17028v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.17028v2-abstract-full" style="display: none;"> Simulating noisy quantum circuits is vital in designing and verifying quantum algorithms in the current NISQ (Noisy Intermediate-Scale Quantum) era, where quantum noise is unavoidable. However, it is much more inefficient than the classical counterpart because of the quantum state explosion problem (the dimension of state space is exponential in the number of qubits) and the complex (non-unitary) representation of noises. Consequently, only noisy circuits with up to about 50 qubits can be simulated approximately well. This paper introduces a novel approximation algorithm for simulating noisy quantum circuits when the noisy effectiveness is insignificant to improve the scalability of the circuits that can be simulated. The algorithm is based on a new tensor network diagram for the noisy simulation and uses the singular value decomposition to approximate the tensors of quantum noises in the diagram. The contraction of the tensor network diagram is implemented on Google's TensorNetwork. The effectiveness and utility of the algorithm are demonstrated by experimenting on a series of practical quantum circuits with realistic superconducting noise models. As a result, our algorithm can approximately simulate quantum circuits with up to 225 qubits and 20 noises (within about 1.8 hours). In particular, our method offers a speedup over the commonly-used approximation (sampling) algorithm -- quantum trajectories method. Furthermore, our approach can significantly reduce the number of samples in the quantum trajectories method when the noise rate is small enough. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.17028v2-abstract-full').style.display = 'none'; document.getElementById('2211.17028v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.11173">arXiv:2207.11173</a> <span> [<a href="https://arxiv.org/pdf/2207.11173">pdf</a>, <a href="https://arxiv.org/format/2207.11173">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="Computers and Society">cs.CY</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> Verifying Fairness in Quantum Machine Learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.11173v1-abstract-short" style="display: inline;"> Due to the beyond-classical capability of quantum computing, quantum machine learning is applied independently or embedded in classical models for decision making, especially in the field of finance. Fairness and other ethical issues are often one of the main concerns in decision making. In this work, we define a formal framework for the fairness verification and analysis of quantum machine learni… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.11173v1-abstract-full').style.display = 'inline'; document.getElementById('2207.11173v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.11173v1-abstract-full" style="display: none;"> Due to the beyond-classical capability of quantum computing, quantum machine learning is applied independently or embedded in classical models for decision making, especially in the field of finance. Fairness and other ethical issues are often one of the main concerns in decision making. In this work, we define a formal framework for the fairness verification and analysis of quantum machine learning decision models, where we adopt one of the most popular notions of fairness in the literature based on the intuition -- any two similar individuals must be treated similarly and are thus unbiased. We show that quantum noise can improve fairness and develop an algorithm to check whether a (noisy) quantum machine learning model is fair. In particular, this algorithm can find bias kernels of quantum data (encoding individuals) during checking. These bias kernels generate infinitely many bias pairs for investigating the unfairness of the model. Our algorithm is designed based on a highly efficient data structure -- Tensor Networks -- and implemented on Google's TensorFlow Quantum. The utility and effectiveness of our algorithm are confirmed by the experimental results, including income prediction and credit scoring on real-world data, for a class of random (noisy) quantum decision models with 27 qubits ($2^{27}$-dimensional state space) tripling ($2^{18}$ times more than) that of the state-of-the-art algorithms for verifying quantum machine learning models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.11173v1-abstract-full').style.display = 'none'; document.getElementById('2207.11173v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.10880">arXiv:2206.10880</a> <span> [<a href="https://arxiv.org/pdf/2206.10880">pdf</a>, <a href="https://arxiv.org/ps/2206.10880">ps</a>, <a href="https://arxiv.org/format/2206.10880">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"> VeriQBench: A Benchmark for Multiple Types of Quantum Circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+K">Kean Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Hong%2C+X">Xin Hong</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+M">Mingyu Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Junyi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qisheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.10880v1-abstract-short" style="display: inline;"> In this paper, we introduce VeriQBench -- an open source benchmark for quantum circuits. It offers high-level quantum circuit abstractions of various circuit types, including 1) combinational, 2) dynamic, 3) sequential, and 4) variational quantum circuits, which cover almost all existing types of quantum circuits in the literature. Meanwhile, VeriQBench is a versatile benchmark which can be used i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10880v1-abstract-full').style.display = 'inline'; document.getElementById('2206.10880v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.10880v1-abstract-full" style="display: none;"> In this paper, we introduce VeriQBench -- an open source benchmark for quantum circuits. It offers high-level quantum circuit abstractions of various circuit types, including 1) combinational, 2) dynamic, 3) sequential, and 4) variational quantum circuits, which cover almost all existing types of quantum circuits in the literature. Meanwhile, VeriQBench is a versatile benchmark which can be used in verifying quantum software for different applications, as is evidenced by the existing works including quantum circuit verification (e.g., equivalence checking [Hon+21a; WLY21] and model checking [Yin21]), simulation (e.g., fault simulation), testing (e.g., test pattern generation [CY22]) and debugging (e.g., runtime assertions [Li+20b]). All the circuits are described in OpenQASM and are validated on Qiskit and QCOR simulators. With the hope that it can be used by other researchers, VeriQBench is released at: https://github.com/Veri-Q/Benchmark. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.10880v1-abstract-full').style.display = 'none'; document.getElementById('2206.10880v1-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 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.13522">arXiv:2203.13522</a> <span> [<a href="https://arxiv.org/pdf/2203.13522">pdf</a>, <a href="https://arxiv.org/ps/2203.13522">ps</a>, <a href="https://arxiv.org/format/2203.13522">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="Computational Complexity">cs.CC</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/10.1109/TIT.2024.3399014">10.1109/TIT.2024.3399014 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> New Quantum Algorithms for Computing Quantum Entropies and Distances </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qisheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Junyi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhicheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.13522v3-abstract-short" style="display: inline;"> We propose a series of quantum algorithms for computing a wide range of quantum entropies and distances, including the von Neumann entropy, quantum R茅nyi entropy, trace distance, and fidelity. The proposed algorithms significantly outperform the prior best (and even quantum) ones in the low-rank case, some of which achieve exponential speedups. In particular, for $N$-dimensional quantum states of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.13522v3-abstract-full').style.display = 'inline'; document.getElementById('2203.13522v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.13522v3-abstract-full" style="display: none;"> We propose a series of quantum algorithms for computing a wide range of quantum entropies and distances, including the von Neumann entropy, quantum R茅nyi entropy, trace distance, and fidelity. The proposed algorithms significantly outperform the prior best (and even quantum) ones in the low-rank case, some of which achieve exponential speedups. In particular, for $N$-dimensional quantum states of rank $r$, our proposed quantum algorithms for computing the von Neumann entropy, trace distance and fidelity within additive error $\varepsilon$ have time complexity of $\tilde O(r/\varepsilon^2)$, $\tilde O(r^5/\varepsilon^6)$ and $\tilde O(r^{6.5}/\varepsilon^{7.5})$, respectively. By contrast, prior quantum algorithms for the von Neumann entropy and trace distance usually have time complexity $惟(N)$, and the prior best one for fidelity has time complexity $\tilde O(r^{12.5}/\varepsilon^{13.5})$. The key idea of our quantum algorithms is to extend block-encoding from unitary operators in previous work to quantum states (i.e., density operators). It is realized by developing several convenient techniques to manipulate quantum states and extract information from them. The advantage of our techniques over the existing methods is that no restrictions on density operators are required; in sharp contrast, the previous methods usually require a lower bound on the minimal non-zero eigenvalue of density operators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.13522v3-abstract-full').style.display = 'none'; document.getElementById('2203.13522v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Final version. 58 pages, 5 tables, 1 figure. Minor corrections to Theorem 3.1, Theorem 3.4, and Corollary 3.5</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> IEEE Transactions on Information Theory, 70(8): 5653-5680, 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.00382">arXiv:2105.00382</a> <span> [<a href="https://arxiv.org/pdf/2105.00382">pdf</a>, <a href="https://arxiv.org/format/2105.00382">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="Logic in Computer Science">cs.LO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Number Theory">math.NT</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/10.4230/LIPIcs.CONCUR.2021.13">10.4230/LIPIcs.CONCUR.2021.13 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Model Checking Quantum Continuous-Time Markov Chains </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+M">Ming Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Mei%2C+J">Jingyi Mei</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+N">Nengkun Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2105.00382v1-abstract-short" style="display: inline;"> Verifying quantum systems has attracted a lot of interests in the last decades. In this paper, we initialised the model checking of quantum continuous-time Markov chain (QCTMC). As a real-time system, we specify the temporal properties on QCTMC by signal temporal logic (STL). To effectively check the atomic propositions in STL, we develop a state-of-art real root isolation algorithm under Schanuel… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.00382v1-abstract-full').style.display = 'inline'; document.getElementById('2105.00382v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.00382v1-abstract-full" style="display: none;"> Verifying quantum systems has attracted a lot of interests in the last decades. In this paper, we initialised the model checking of quantum continuous-time Markov chain (QCTMC). As a real-time system, we specify the temporal properties on QCTMC by signal temporal logic (STL). To effectively check the atomic propositions in STL, we develop a state-of-art real root isolation algorithm under Schanuel's conjecture; further, we check the general STL formula by interval operations with a bottom-up fashion, whose query complexity turns out to be linear in the size of the input formula by calling the real root isolation algorithm. A running example of an open quantum walk is provided to demonstrate our method. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.00382v1-abstract-full').style.display = 'none'; document.getElementById('2105.00382v1-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 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.09076">arXiv:2103.09076</a> <span> [<a href="https://arxiv.org/pdf/2103.09076">pdf</a>, <a href="https://arxiv.org/ps/2103.09076">ps</a>, <a href="https://arxiv.org/format/2103.09076">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/10.1109/TIT.2022.3203985">10.1109/TIT.2022.3203985 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Algorithm for Fidelity Estimation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qisheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhicheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+K">Kean Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Junyi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2103.09076v2-abstract-short" style="display: inline;"> For two unknown mixed quantum states $蟻$ and $蟽$ in an $N$-dimensional Hilbert space, computing their fidelity $F(蟻,蟽)$ is a basic problem with many important applications in quantum computing and quantum information, for example verification and characterization of the outputs of a quantum computer, and design and analysis of quantum algorithms. In this paper, we propose a quantum algorithm that… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.09076v2-abstract-full').style.display = 'inline'; document.getElementById('2103.09076v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.09076v2-abstract-full" style="display: none;"> For two unknown mixed quantum states $蟻$ and $蟽$ in an $N$-dimensional Hilbert space, computing their fidelity $F(蟻,蟽)$ is a basic problem with many important applications in quantum computing and quantum information, for example verification and characterization of the outputs of a quantum computer, and design and analysis of quantum algorithms. In this paper, we propose a quantum algorithm that solves this problem in $\operatorname{poly}(\log (N), r, 1/\varepsilon)$ time, where $r$ is the lower rank of $蟻$ and $蟽$, and $\varepsilon$ is the desired precision, provided that the purifications of $蟻$ and $蟽$ are prepared by quantum oracles. This algorithm exhibits an exponential speedup over the best known algorithm (based on quantum state tomography) which has time complexity polynomial in $N$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.09076v2-abstract-full').style.display = 'none'; document.getElementById('2103.09076v2-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 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Final version with an improvement over the previous version. 19 pages, 2 tables, 1 algorithm</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> IEEE Transactions on Information Theory, 69(1): 273-282, 2023 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.03460">arXiv:2101.03460</a> <span> [<a href="https://arxiv.org/pdf/2101.03460">pdf</a>, <a href="https://arxiv.org/format/2101.03460">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-019-0208-1">10.1038/s41534-019-0208-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Random Number Generation with Uncharacterized Laser and Sunlight </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+X">Xuan Han</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+X">Xiao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zheng-Ping Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.03460v1-abstract-short" style="display: inline;"> The entropy or randomness source is an essential ingredient in random number generation. Quantum random number generators generally require well modeled and calibrated light sources, such as a laser, to generate randomness. With uncharacterized light sources, such as sunlight or an uncharacterized laser, genuine randomness is practically hard to be quantified or extracted owing to its unknown or c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.03460v1-abstract-full').style.display = 'inline'; document.getElementById('2101.03460v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.03460v1-abstract-full" style="display: none;"> The entropy or randomness source is an essential ingredient in random number generation. Quantum random number generators generally require well modeled and calibrated light sources, such as a laser, to generate randomness. With uncharacterized light sources, such as sunlight or an uncharacterized laser, genuine randomness is practically hard to be quantified or extracted owing to its unknown or complicated structure. By exploiting a recently proposed source-independent randomness generation protocol, we theoretically modify it by considering practical issues and experimentally realize the modified scheme with an uncharacterized laser and a sunlight source. The extracted randomness is guaranteed to be secure independent of its source and the randomness generation speed reaches 1 Mbps, three orders of magnitude higher than the original realization. Our result signifies the power of quantum technology in randomness generation and paves the way to high-speed semi-self-testing quantum random number generators with practical light sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.03460v1-abstract-full').style.display = 'none'; document.getElementById('2101.03460v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 5, 97 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2011.02807">arXiv:2011.02807</a> <span> [<a href="https://arxiv.org/pdf/2011.02807">pdf</a>, <a href="https://arxiv.org/format/2011.02807">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/PhysRevX.11.031009">10.1103/PhysRevX.11.031009 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Field demonstration of distributed quantum sensing without post-selection </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+S">Si-Ran Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yu-Zhe Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wen-Zhao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Cheng-Long Li</a>, <a href="/search/quant-ph?searchtype=author&query=Bai%2C+B">Bing Bai</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming-Han Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+J">Jingyun Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="2011.02807v1-abstract-short" style="display: inline;"> Distributed quantum sensing can provide quantum-enhanced sensitivity beyond the shot-noise limit (SNL) for sensing spatially distributed parameters. To date, distributed quantum sensing experiments have been mostly accomplished in laboratory environments without a real space separation for the sensors. In addition, the post-selection is normally assumed to demonstrate the sensitivity advantage ove… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.02807v1-abstract-full').style.display = 'inline'; document.getElementById('2011.02807v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2011.02807v1-abstract-full" style="display: none;"> Distributed quantum sensing can provide quantum-enhanced sensitivity beyond the shot-noise limit (SNL) for sensing spatially distributed parameters. To date, distributed quantum sensing experiments have been mostly accomplished in laboratory environments without a real space separation for the sensors. In addition, the post-selection is normally assumed to demonstrate the sensitivity advantage over the SNL. Here, we demonstrate distributed quantum sensing in field and show the unconditional violation (without post-selection) of SNL up to 0.916 dB for the field distance of 240 m. The achievement is based on a loophole free Bell test setup with entangled photon pairs at the averaged heralding efficiency of 73.88%. Moreover, to test quantum sensing in real life, we demonstrate the experiment for long distances (with 10-km fiber) together with the sensing of a completely random and unknown parameter. The results represent an important step towards a practical quantum sensing network for widespread applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.02807v1-abstract-full').style.display = 'none'; document.getElementById('2011.02807v1-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 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. X 11, 031009 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.08217">arXiv:2009.08217</a> <span> [<a href="https://arxiv.org/pdf/2009.08217">pdf</a>, <a href="https://arxiv.org/format/2009.08217">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.402560">10.1364/OE.402560 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Chromatic interferometry with small frequency differences </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qu%2C+L">Luo-Yuan Qu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+L">Lu-Chuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cotler%2C+J">Jordan Cotler</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+F">Fei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+M">Ming-Yang Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+Q">Quan Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+X">Xiu-Ping Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu-Ao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wilczek%2C+F">Frank Wilczek</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="2009.08217v1-abstract-short" style="display: inline;"> By developing a `two-crystal' method for color erasure, we can broaden the scope of chromatic interferometry to include optical photons whose frequency difference falls outside of the 400 nm to 4500 nm wavelength range, which is the passband of a PPLN crystal. We demonstrate this possibility experimentally, by observing interference patterns between sources at 1064.4 nm and 1063.6 nm, correspondin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.08217v1-abstract-full').style.display = 'inline'; document.getElementById('2009.08217v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.08217v1-abstract-full" style="display: none;"> By developing a `two-crystal' method for color erasure, we can broaden the scope of chromatic interferometry to include optical photons whose frequency difference falls outside of the 400 nm to 4500 nm wavelength range, which is the passband of a PPLN crystal. We demonstrate this possibility experimentally, by observing interference patterns between sources at 1064.4 nm and 1063.6 nm, corresponding to a frequency difference of about 200 GHz. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.08217v1-abstract-full').style.display = 'none'; document.getElementById('2009.08217v1-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 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Opt. Express 28, 32294 (2000) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.03618">arXiv:2009.03618</a> <span> [<a href="https://arxiv.org/pdf/2009.03618">pdf</a>, <a href="https://arxiv.org/format/2009.03618">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/10.26421/QIC21.5-6-4">10.26421/QIC21.5-6-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> An HHL-Based Algorithm for Computing Hitting Probabilities of Quantum Random Walks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Q">Qisheng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.03618v2-abstract-short" style="display: inline;"> We present a novel application of the HHL (Harrow-Hassidim-Lloyd) algorithm -- a quantum algorithm solving systems of linear equations -- in solving an open problem about quantum random walks, namely computing hitting (or absorption) probabilities of a general (not only Hadamard) one-dimensional quantum random walks with two absorbing boundaries. This is achieved by a simple observation that the p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.03618v2-abstract-full').style.display = 'inline'; document.getElementById('2009.03618v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.03618v2-abstract-full" style="display: none;"> We present a novel application of the HHL (Harrow-Hassidim-Lloyd) algorithm -- a quantum algorithm solving systems of linear equations -- in solving an open problem about quantum random walks, namely computing hitting (or absorption) probabilities of a general (not only Hadamard) one-dimensional quantum random walks with two absorbing boundaries. This is achieved by a simple observation that the problem of computing hitting probabilities of quantum random walks can be reduced to inverting a matrix. Then a quantum algorithm with the HHL algorithm as a subroutine is developed for solving the problem, which is faster than the known classical algorithms by numerical experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.03618v2-abstract-full').style.display = 'none'; document.getElementById('2009.03618v2-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 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Information and Computation, 21(5-6): 395-408, 2021 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.07230">arXiv:2008.07230</a> <span> [<a href="https://arxiv.org/pdf/2008.07230">pdf</a>, <a href="https://arxiv.org/format/2008.07230">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/978-3-030-81685-8_7">10.1007/978-3-030-81685-8_7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Robustness Verification of Quantum Classifiers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+W">Wang Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.07230v2-abstract-short" style="display: inline;"> Several important models of machine learning algorithms have been successfully generalized to the quantum world, with potential speedup to training classical classifiers and applications to data analytics in quantum physics that can be implemented on the near future quantum computers. However, quantum noise is a major obstacle to the practical implementation of quantum machine learning. In this wo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.07230v2-abstract-full').style.display = 'inline'; document.getElementById('2008.07230v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.07230v2-abstract-full" style="display: none;"> Several important models of machine learning algorithms have been successfully generalized to the quantum world, with potential speedup to training classical classifiers and applications to data analytics in quantum physics that can be implemented on the near future quantum computers. However, quantum noise is a major obstacle to the practical implementation of quantum machine learning. In this work, we define a formal framework for the robustness verification and analysis of quantum machine learning algorithms against noises. A robust bound is derived and an algorithm is developed to check whether or not a quantum machine learning algorithm is robust with respect to quantum training data. In particular, this algorithm can find adversarial examples during checking. Our approach is implemented on Google's TensorFlow Quantum and can verify the robustness of quantum machine learning algorithms with respect to a small disturbance of noises, derived from the surrounding environment. The effectiveness of our robust bound and algorithm is confirmed by the experimental results, including quantum bits classification as the "Hello World" example, quantum phase recognition and cluster excitation detection from real world intractable physical problems, and the classification of MNIST from the classical world. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.07230v2-abstract-full').style.display = 'none'; document.getElementById('2008.07230v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.07823">arXiv:1910.07823</a> <span> [<a href="https://arxiv.org/pdf/1910.07823">pdf</a>, <a href="https://arxiv.org/format/1910.07823">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.124.070501">10.1103/PhysRevLett.124.070501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Sending-or-Not-Sending with Independent Lasers: Secure Twin-Field Quantum Key Distribution Over 509 km </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Long Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Z">Zong-Wen Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Hai Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming-Jun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Hao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1910.07823v1-abstract-short" style="display: inline;"> Twin field quantum key distribution promises high key rates at long distance to beat the rate distance limit. Here, applying the sending or not sending TF QKD protocol, we experimentally demonstrate a secure key distribution breaking the absolute key rate limit of repeaterless QKD over 509 km, 408 km ultra-low loss optical fibre and 350 km standard optical fibre. Two independent lasers are used as… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.07823v1-abstract-full').style.display = 'inline'; document.getElementById('1910.07823v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.07823v1-abstract-full" style="display: none;"> Twin field quantum key distribution promises high key rates at long distance to beat the rate distance limit. Here, applying the sending or not sending TF QKD protocol, we experimentally demonstrate a secure key distribution breaking the absolute key rate limit of repeaterless QKD over 509 km, 408 km ultra-low loss optical fibre and 350 km standard optical fibre. Two independent lasers are used as the source with remote frequency locking technique over 500 km fiber distance; Practical optical fibers are used as the optical path with appropriate noise filtering; And finite key effects are considered in the key rate analysis. The secure key rates obtained at different distances are more than 5 times higher than the conditional limit of repeaterless QKD, a bound value assuming the same detection loss in the comparison. The achieved secure key rate is also higher than that a traditional QKD protocol running with a perfect repeaterless QKD device and even if an infinite number of sent pulses. Our result shows that the protocol and technologies applied in this experiment enable TF QKD to achieve high secure key rate at long distribution distance, and hence practically useful for field implementation of intercity QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.07823v1-abstract-full').style.display = 'none'; document.getElementById('1910.07823v1-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, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </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, 10 figures and 8 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 124, 070501 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1908.05022">arXiv:1908.05022</a> <span> [<a href="https://arxiv.org/pdf/1908.05022">pdf</a>, <a href="https://arxiv.org/format/1908.05022">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.123.090502">10.1103/PhysRevLett.123.090502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Coherence Witness with Untrusted Measurement Devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Nie%2C+Y">You-Qi Nie</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Hongyi Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</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="1908.05022v1-abstract-short" style="display: inline;"> Coherence is a fundamental resource in quantum information processing, which can be certified by a coherence witness. Due to the imperfection of measurement devices, a conventional coherence witness may lead to fallacious results. We show that the conventional witness could mistake an incoherent state as a state with coherence due to the inaccurate settings of measurement bases. In order to make t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.05022v1-abstract-full').style.display = 'inline'; document.getElementById('1908.05022v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1908.05022v1-abstract-full" style="display: none;"> Coherence is a fundamental resource in quantum information processing, which can be certified by a coherence witness. Due to the imperfection of measurement devices, a conventional coherence witness may lead to fallacious results. We show that the conventional witness could mistake an incoherent state as a state with coherence due to the inaccurate settings of measurement bases. In order to make the witness result reliable, we propose a measurement-device-independent coherence witness scheme without any assumptions on the measurement settings. We introduce the decoy-state method to significantly increase the capability of recognizing states with coherence. Furthermore, we experimentally demonstrate the scheme in a time-bin encoding optical system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.05022v1-abstract-full').style.display = 'none'; document.getElementById('1908.05022v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 August, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2019. </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, 7 figures, including Supplemental Material, accepted for publication in Physical Review Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 123, 090502 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.01823">arXiv:1905.01823</a> <span> [<a href="https://arxiv.org/pdf/1905.01823">pdf</a>, <a href="https://arxiv.org/format/1905.01823">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.123.243601">10.1103/PhysRevLett.123.243601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Color Erasure Detectors Enable Chromatic Interferometry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Qu%2C+L">Luo-Yuan Qu</a>, <a href="/search/quant-ph?searchtype=author&query=Cotler%2C+J">Jordan Cotler</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+F">Fei Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+M">Ming-Yang Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+X">Xiuping Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yu-Ao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wilczek%2C+F">Frank Wilczek</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="1905.01823v2-abstract-short" style="display: inline;"> By engineering and manipulating quantum entanglement between incoming photons and experimental apparatus, we construct single-photon detectors which cannot distinguish between photons of very different wavelengths. These color erasure detectors enable a new kind of intensity interferometry, with potential applications in microscopy and astronomy. We demonstrate chromatic interferometry experimenta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.01823v2-abstract-full').style.display = 'inline'; document.getElementById('1905.01823v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.01823v2-abstract-full" style="display: none;"> By engineering and manipulating quantum entanglement between incoming photons and experimental apparatus, we construct single-photon detectors which cannot distinguish between photons of very different wavelengths. These color erasure detectors enable a new kind of intensity interferometry, with potential applications in microscopy and astronomy. We demonstrate chromatic interferometry experimentally, observing robust interference using both coherent and incoherent photon sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.01823v2-abstract-full').style.display = 'none'; document.getElementById('1905.01823v2-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 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 123, 243601 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.06268">arXiv:1902.06268</a> <span> [<a href="https://arxiv.org/pdf/1902.06268">pdf</a>, <a href="https://arxiv.org/format/1902.06268">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cryptography and Security">cs.CR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.123.100505">10.1103/PhysRevLett.123.100505 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Twin-Field Quantum Key Distribution Through Sending-or-Not-Sending </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Z">Zong-Wen Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Long Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1902.06268v2-abstract-short" style="display: inline;"> Channel loss seems to be the most severe limitation on the practical application of long distance quantum key distribution. The idea of twin-field quantum key distribution can improve the key rate from the linear scale of channel loss in the traditional decoy-state method to the square root scale of the channel transmittance. However, the technical demanding is rather tough because it requests sin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.06268v2-abstract-full').style.display = 'inline'; document.getElementById('1902.06268v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.06268v2-abstract-full" style="display: none;"> Channel loss seems to be the most severe limitation on the practical application of long distance quantum key distribution. The idea of twin-field quantum key distribution can improve the key rate from the linear scale of channel loss in the traditional decoy-state method to the square root scale of the channel transmittance. However, the technical demanding is rather tough because it requests single photon level interference of two remote independent lasers. Here, we adopt the technology developed in the frequency and time transfer to lock two independent lasers' wavelengths and utilize additional phase reference light to estimate and compensate the fiber fluctuation. Further with a single photon detector with high detection rate, we demonstrate twin field quantum key distribution through the sending-or-not-sending protocol with realistic phase drift over 300 km optical fiber spools. We calculate the secure key rates with finite size effect. The secure key rate at 300 km ($1.96\times10^{-6}$) is higher than that of the repeaterless secret key capacity ($8.64\times10^{-7}$). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.06268v2-abstract-full').style.display = 'none'; document.getElementById('1902.06268v2-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, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 10 figures and 9 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 123, 100505 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.03218">arXiv:1902.03218</a> <span> [<a href="https://arxiv.org/pdf/1902.03218">pdf</a>, <a href="https://arxiv.org/format/1902.03218">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="Logic in Computer Science">cs.LO</span> </div> </div> <p class="title is-5 mathjax"> Model Checking Applied to Quantum Physics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+Y">Yuan Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Turrini%2C+A">Andrea Turrini</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1902.03218v1-abstract-short" style="display: inline;"> Model checking has been successfully applied to verification of computer hardware and software, communication systems and even biological systems. In this paper, we further push the boundary of its applications and show that it can be adapted for applications in quantum physics. More explicitly, we show how quantum statistical and many-body systems can be modeled as quantum Markov chains, and some… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.03218v1-abstract-full').style.display = 'inline'; document.getElementById('1902.03218v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.03218v1-abstract-full" style="display: none;"> Model checking has been successfully applied to verification of computer hardware and software, communication systems and even biological systems. In this paper, we further push the boundary of its applications and show that it can be adapted for applications in quantum physics. More explicitly, we show how quantum statistical and many-body systems can be modeled as quantum Markov chains, and some of their properties that interest physicists can be specified in linear-time temporal logics. Then we present an efficient algorithm to check these properties. A few case studies are given to demonstrate the use of our algorithm to actual quantum physical problems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.03218v1-abstract-full').style.display = 'none'; document.getElementById('1902.03218v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.04439">arXiv:1901.04439</a> <span> [<a href="https://arxiv.org/pdf/1901.04439">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="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/PhysRevLett.125.117401">10.1103/PhysRevLett.125.117401 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Photonic Topological Mode Bound to a Vortex </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Menssen%2C+A+J">Adrian J Menssen</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jun Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Felce%2C+D">David Felce</a>, <a href="/search/quant-ph?searchtype=author&query=Booth%2C+M+J">Martin J Booth</a>, <a href="/search/quant-ph?searchtype=author&query=Walmsley%2C+I+A">Ian A Walmsley</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="1901.04439v2-abstract-short" style="display: inline;"> Topological photonics sheds light on some of the surprising phenomena seen in condensed matter physics that arise with the appearance of topological invariants. Optical waveguides provide a well-controlled platform to investigate effects that relate to different topological phases of matter, providing insight into phenomena such as topological insulators and superconductors by direct simulation of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.04439v2-abstract-full').style.display = 'inline'; document.getElementById('1901.04439v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.04439v2-abstract-full" style="display: none;"> Topological photonics sheds light on some of the surprising phenomena seen in condensed matter physics that arise with the appearance of topological invariants. Optical waveguides provide a well-controlled platform to investigate effects that relate to different topological phases of matter, providing insight into phenomena such as topological insulators and superconductors by direct simulation of the states that are protected by the topology of the system. Here, we observe a mode associated with a topological defect in the bulk of a 2D photonic material by introducing a vortex distortion to an hexagonal lattice and analogous to graphene. These observations are made possible by advances in our experimental methods. We were able to manufacture uniform large two-dimensional photonic crystal structures, containing thousands of identical waveguides arranged in two dimensions, and we developed a new method to excite multiples of these waveguides with a well-defined light field. This allows us to probe the detailed spatial features of topological defect modes for the first time. The observed modes lie mid-gap at zero energy and are closely related to Majorana bound states in superconducting vortices. This is the first experimental demonstration of a mode that is a solution to the Dirac equation in the presence of a vortex, as proposed by Jackiw and Rossi. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.04439v2-abstract-full').style.display = 'none'; document.getElementById('1901.04439v2-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 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 January, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 125, 117401 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.09611">arXiv:1807.09611</a> <span> [<a href="https://arxiv.org/pdf/1807.09611">pdf</a>, <a href="https://arxiv.org/format/1807.09611">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/s41586-018-0559-3">10.1038/s41586-018-0559-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Device independent quantum random number generation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Q">Qi Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming-Han Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yanbao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Bai%2C+B">Bing Bai</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wen-Zhao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+C">Cheng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+X">Xiao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Munro%2C+W+J">W. J. Munro</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+J">Jingyun Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1807.09611v2-abstract-short" style="display: inline;"> Randomness is critical for many information processing applications, including numerical modeling and cryptography. Device-independent quantum random number generation (DIQRNG) based on the loophole free violation of Bell inequality produces unpredictable genuine randomness without any device assumption and is therefore an ultimate goal in the field of quantum information science. However, due to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.09611v2-abstract-full').style.display = 'inline'; document.getElementById('1807.09611v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.09611v2-abstract-full" style="display: none;"> Randomness is critical for many information processing applications, including numerical modeling and cryptography. Device-independent quantum random number generation (DIQRNG) based on the loophole free violation of Bell inequality produces unpredictable genuine randomness without any device assumption and is therefore an ultimate goal in the field of quantum information science. However, due to formidable technical challenges, there were very few reported experimental studies of DIQRNG, which were vulnerable to the adversaries. Here we present a fully functional DIQRNG against the most general quantum adversaries. We construct a robust experimental platform that realizes Bell inequality violation with entangled photons with detection and locality loopholes closed simultaneously. This platform enables a continuous recording of a large volume of data sufficient for security analysis against the general quantum side information and without assuming independent and identical distribution. Lastly, by developing a large Toeplitz matrix (137.90 Gb $\times$ 62.469 Mb) hashing technique, we demonstrate that this DIQRNG generates $6.2469\times 10^7$ quantum-certified random bits in 96 hours (or 181 bits/s) with uniformity within $10^{-5}$. We anticipate this DIQRNG may have profound impact on the research of quantum randomness and information-secured applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.09611v2-abstract-full').style.display = 'none'; document.getElementById('1807.09611v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">35 pages, 10 figures. The section "randomness extraction" in supplementary is revised in order to avoid text overlap</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 562, 548 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.00918">arXiv:1807.00918</a> <span> [<a href="https://arxiv.org/pdf/1807.00918">pdf</a>, <a href="https://arxiv.org/format/1807.00918">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.99.022115">10.1103/PhysRevA.99.022115 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental test of measurement dependent local Bell inequality with human free will </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+X">Xiao Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+C">Cheng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+J">Jiaqiang Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Ming-Han Li</a>, <a href="/search/quant-ph?searchtype=author&query=Abellan%2C+C">Carlos Abellan</a>, <a href="/search/quant-ph?searchtype=author&query=Mitchell%2C+M+W">Morgan W. Mitchell</a>, <a href="/search/quant-ph?searchtype=author&query=Shi%2C+S">Sheng-Cai Shi</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+J">Jingyun Fan</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1807.00918v1-abstract-short" style="display: inline;"> A Bell test can rule out local realistic models, and has potential applications in communications and information tasks. For example, a Bell inequality violation can certify the presence of intrinsic randomness in measurement outcomes, which then can be used to generate unconditional randomness. A Bell test requires, however, measurements that are chosen independently of other physical variables i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.00918v1-abstract-full').style.display = 'inline'; document.getElementById('1807.00918v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.00918v1-abstract-full" style="display: none;"> A Bell test can rule out local realistic models, and has potential applications in communications and information tasks. For example, a Bell inequality violation can certify the presence of intrinsic randomness in measurement outcomes, which then can be used to generate unconditional randomness. A Bell test requires, however, measurements that are chosen independently of other physical variables in the test, as would be the case if the measurement settings were themselves unconditionally random. This situation seems to create a "bootstrapping problem" that was recently addressed in The BIG Bell Test, a collection of Bell tests and related tests using human setting choices. Here we report in detail our experimental methods and results within the BIG Bell Test. We perform a experimental test of a special type of Bell inequality - the measurement dependent local inequality. With this inequality, even a small amount of measurement independence makes it possible to disprove local realistic models. The experiment uses human-generated random numbers to select the measurement settings in real time, and implements the measurement setting with space-like separation from the distant measurement. The experimental result shows a Bell inequality violation that cannot be explained by local hidden variable models with independence parameter (as defined in [Putz et al. Phys. Rev. Lett. 113, 190402 (2014).] ) l > 0.10 +/- 0.05. This result quantifies the degree to which a hidden variable model would need to constrain human choices, if it is to reproduce the experimental results. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.00918v1-abstract-full').style.display = 'none'; document.getElementById('1807.00918v1-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, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 99, 022115 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.04431">arXiv:1805.04431</a> <span> [<a href="https://arxiv.org/pdf/1805.04431">pdf</a>, <a href="https://arxiv.org/format/1805.04431">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/s41586-018-0085-3">10.1038/s41586-018-0085-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Challenging local realism with human choices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=The+BIG+Bell+Test+Collaboration"> The BIG Bell Test Collaboration</a>, <a href="/search/quant-ph?searchtype=author&query=Abell%C3%A1n%2C+C">C. Abell谩n</a>, <a href="/search/quant-ph?searchtype=author&query=Ac%C3%ADn%2C+A">A. Ac铆n</a>, <a href="/search/quant-ph?searchtype=author&query=Alarc%C3%B3n%2C+A">A. Alarc贸n</a>, <a href="/search/quant-ph?searchtype=author&query=Alibart%2C+O">O. Alibart</a>, <a href="/search/quant-ph?searchtype=author&query=Andersen%2C+C+K">C. K. Andersen</a>, <a href="/search/quant-ph?searchtype=author&query=Andreoli%2C+F">F. Andreoli</a>, <a href="/search/quant-ph?searchtype=author&query=Beckert%2C+A">A. Beckert</a>, <a href="/search/quant-ph?searchtype=author&query=Beduini%2C+F+A">F. A. Beduini</a>, <a href="/search/quant-ph?searchtype=author&query=Bendersky%2C+A">A. Bendersky</a>, <a href="/search/quant-ph?searchtype=author&query=Bentivegna%2C+M">M. Bentivegna</a>, <a href="/search/quant-ph?searchtype=author&query=Bierhorst%2C+P">P. Bierhorst</a>, <a href="/search/quant-ph?searchtype=author&query=Burchardt%2C+D">D. Burchardt</a>, <a href="/search/quant-ph?searchtype=author&query=Cabello%2C+A">A. Cabello</a>, <a href="/search/quant-ph?searchtype=author&query=Cari%C3%B1e%2C+J">J. Cari帽e</a>, <a href="/search/quant-ph?searchtype=author&query=Carrasco%2C+S">S. Carrasco</a>, <a href="/search/quant-ph?searchtype=author&query=Carvacho%2C+G">G. Carvacho</a>, <a href="/search/quant-ph?searchtype=author&query=Cavalcanti%2C+D">D. Cavalcanti</a>, <a href="/search/quant-ph?searchtype=author&query=Chaves%2C+R">R. Chaves</a>, <a href="/search/quant-ph?searchtype=author&query=Cort%C3%A9s-Vega%2C+J">J. Cort茅s-Vega</a>, <a href="/search/quant-ph?searchtype=author&query=Cuevas%2C+A">A. Cuevas</a>, <a href="/search/quant-ph?searchtype=author&query=Delgado%2C+A">A. Delgado</a>, <a href="/search/quant-ph?searchtype=author&query=de+Riedmatten%2C+H">H. de Riedmatten</a>, <a href="/search/quant-ph?searchtype=author&query=Eichler%2C+C">C. Eichler</a>, <a href="/search/quant-ph?searchtype=author&query=Farrera%2C+P">P. Farrera</a> , et al. (83 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.04431v3-abstract-short" style="display: inline;"> A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Although technology can satisfy the first two of these requirements, the use of physical devices to choose settings in a Bell test involves… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.04431v3-abstract-full').style.display = 'inline'; document.getElementById('1805.04431v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.04431v3-abstract-full" style="display: none;"> A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Although technology can satisfy the first two of these requirements, the use of physical devices to choose settings in a Bell test involves making assumptions about the physics that one aims to test. Bell himself noted this weakness in using physical setting choices and argued that human `free will' could be used rigorously to ensure unpredictability in Bell tests. Here we report a set of local-realism tests using human choices, which avoids assumptions about predictability in physics. We recruited about 100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable selections and illustrates Bell-test methodology. The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to 12 laboratories on five continents, where 13 experiments tested local realism using photons, single atoms, atomic ensembles, and superconducting devices. Over a 12-hour period on 30 November 2016, participants worldwide provided a sustained data flow of over 1,000 bits per second to the experiments, which used different human-generated data to choose each measurement setting. The observed correlations strongly contradict local realism and other realistic positions in bipartite and tripartite scenarios. Project outcomes include closing the `freedom-of-choice loophole' (the possibility that the setting choices are influenced by `hidden variables' to correlate with the particle properties), the utilization of video-game methods for rapid collection of human generated randomness, and the use of networking techniques for global participation in experimental science. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.04431v3-abstract-full').style.display = 'none'; document.getElementById('1805.04431v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </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 version includes minor changes resulting from reviewer and editorial input. Abstract shortened to fit within arXiv limits</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature, volume 557, pages 212-216 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.04904">arXiv:1802.04904</a> <span> [<a href="https://arxiv.org/pdf/1802.04904">pdf</a>, <a href="https://arxiv.org/ps/1802.04904">ps</a>, <a href="https://arxiv.org/format/1802.04904">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> The Structure of Decoherence-free Subsystems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+Y">Yuan Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.04904v1-abstract-short" style="display: inline;"> Decoherence-free subsystems have been successfully developed as a tool to preserve fragile quantum information against noises. In this letter, we develop a structure theory for decoherence-free subsystems. Based on it, we present an effective algorithm to construct a set of maximal decoherence-free subsystems in the sense that any other such subsystem is a subspace of one of them. As an applicatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.04904v1-abstract-full').style.display = 'inline'; document.getElementById('1802.04904v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.04904v1-abstract-full" style="display: none;"> Decoherence-free subsystems have been successfully developed as a tool to preserve fragile quantum information against noises. In this letter, we develop a structure theory for decoherence-free subsystems. Based on it, we present an effective algorithm to construct a set of maximal decoherence-free subsystems in the sense that any other such subsystem is a subspace of one of them. As an application of these techniques in quantum many body systems, we propose a simple and numerically robust method to determine if two irreducible tensors are repeated, a key step in deciding if they are equivalent in generating matrix product states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.04904v1-abstract-full').style.display = 'none'; document.getElementById('1802.04904v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.09500">arXiv:1710.09500</a> <span> [<a href="https://arxiv.org/pdf/1710.09500">pdf</a>, <a href="https://arxiv.org/format/1710.09500">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="Programming Languages">cs.PL</span> </div> </div> <p class="title is-5 mathjax"> $Q|SI\rangle$: A Quantum Programming Environment </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Shusen Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+L">Li Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yinan Li</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yang He</a>, <a href="/search/quant-ph?searchtype=author&query=Duan%2C+R">Runyao Duan</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1710.09500v1-abstract-short" style="display: inline;"> This paper describes a quantum programming environment, named $Q|SI\rangle$. It is a platform embedded in the .Net language that supports quantum programming using a quantum extension of the $\mathbf{while}$-language. The framework of the platform includes a compiler of the quantum $\mathbf{while}$-language and a suite of tools for simulating quantum computation, optimizing quantum circuits, and a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.09500v1-abstract-full').style.display = 'inline'; document.getElementById('1710.09500v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.09500v1-abstract-full" style="display: none;"> This paper describes a quantum programming environment, named $Q|SI\rangle$. It is a platform embedded in the .Net language that supports quantum programming using a quantum extension of the $\mathbf{while}$-language. The framework of the platform includes a compiler of the quantum $\mathbf{while}$-language and a suite of tools for simulating quantum computation, optimizing quantum circuits, and analyzing and verifying quantum programs. Throughout the paper, using $Q|SI\rangle$ to simulate quantum behaviors on classical platforms with a combination of components is demonstrated. The scalable framework allows the user to program customized functions on the platform. The compiler works as the core of $Q|SI\rangle$ bridging the gap from quantum hardware to quantum software. The built-in decomposition algorithms enable the universal quantum computation on the present quantum hardware. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.09500v1-abstract-full').style.display = 'none'; document.getElementById('1710.09500v1-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 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </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">30 pages, software available at http://www.qcompiler.com</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.02805">arXiv:1710.02805</a> <span> [<a href="https://arxiv.org/pdf/1710.02805">pdf</a>, <a href="https://arxiv.org/format/1710.02805">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.97.012325">10.1103/PhysRevA.97.012325 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Efficient quantum repeater in perspectives of both entanglement concentration rate and LOCC complexity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Su%2C+Z">Zhaofeng Su</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Lvzhou 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="1710.02805v1-abstract-short" style="display: inline;"> Quantum entanglement is an indispensable resource for many significant quantum information processing tasks. However, because of the noise in quantum channels, it is difficult to distribute quantum entanglement over a long distance in practice. A solution for this challenge is the quantum repeater which can extend the distance of entanglement distribution. In this scheme, the time consumption of c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.02805v1-abstract-full').style.display = 'inline'; document.getElementById('1710.02805v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.02805v1-abstract-full" style="display: none;"> Quantum entanglement is an indispensable resource for many significant quantum information processing tasks. However, because of the noise in quantum channels, it is difficult to distribute quantum entanglement over a long distance in practice. A solution for this challenge is the quantum repeater which can extend the distance of entanglement distribution. In this scheme, the time consumption of classical communication and local operations takes an important place in perspective of time efficiency. Motivated by this observation, we exploit the basic quantum repeater scheme in perspectives of not only the optimal rate of entanglement concentration but also the complexity of local operations and classical communication. Firstly, we consider the case where two two-qubit pure states are prepared. We construct a protocol with the optimal entanglement concentration rate and less consumption of local operations and classical communication. We also find a criteria for the projective measurements to achieve the optimal probability. Secondly, we exploit the case where two general pure states are prepared and general measurements are considered. We get an upper bound on the probability for a successful measurement operation to produce a maximally entangled state without any further local operations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.02805v1-abstract-full').style.display = 'none'; document.getElementById('1710.02805v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 97, 012325 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1709.05882">arXiv:1709.05882</a> <span> [<a href="https://arxiv.org/pdf/1709.05882">pdf</a>, <a href="https://arxiv.org/format/1709.05882">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.97.032338">10.1103/PhysRevA.97.032338 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental preparation and verification of quantum money </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Arrazola%2C+J+M">Juan Miguel Arrazola</a>, <a href="/search/quant-ph?searchtype=author&query=Amiri%2C+R">Ryan Amiri</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1709.05882v1-abstract-short" style="display: inline;"> A quantum money scheme enables a trusted bank to provide untrusted users with verifiable quantum banknotes that cannot be forged. In this work, we report an experimental demonstration of the preparation and verification of unforgeable quantum banknotes. We employ a security analysis that takes experimental imperfections fully into account. We measure a total of $3.6\times 10^6$ states in one verif… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1709.05882v1-abstract-full').style.display = 'inline'; document.getElementById('1709.05882v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1709.05882v1-abstract-full" style="display: none;"> A quantum money scheme enables a trusted bank to provide untrusted users with verifiable quantum banknotes that cannot be forged. In this work, we report an experimental demonstration of the preparation and verification of unforgeable quantum banknotes. We employ a security analysis that takes experimental imperfections fully into account. We measure a total of $3.6\times 10^6$ states in one verification round, limiting the forging probability to $10^{-7}$ based on the security analysis. Our results demonstrate the feasibility of preparing and verifying quantum banknotes using currently available experimental techniques. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1709.05882v1-abstract-full').style.display = 'none'; document.getElementById('1709.05882v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 September, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2017. </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, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 97, 032338 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1708.00700">arXiv:1708.00700</a> <span> [<a href="https://arxiv.org/pdf/1708.00700">pdf</a>, <a href="https://arxiv.org/ps/1708.00700">ps</a>, <a href="https://arxiv.org/format/1708.00700">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="Information Theory">cs.IT</span> </div> </div> <p class="title is-5 mathjax"> Super-activating Quantum Memory with Entanglement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+Y">Yuan Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1708.00700v3-abstract-short" style="display: inline;"> Noiseless subsystems were proved to be an efficient and faithful approach to preserve fragile information against decoherence in quantum information processing and quantum computation. They were employed to design a general (hybrid) quantum memory cell model that can store both quantum and classical information. In this paper, we find an interesting new phenomenon that the purely classical memory… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1708.00700v3-abstract-full').style.display = 'inline'; document.getElementById('1708.00700v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1708.00700v3-abstract-full" style="display: none;"> Noiseless subsystems were proved to be an efficient and faithful approach to preserve fragile information against decoherence in quantum information processing and quantum computation. They were employed to design a general (hybrid) quantum memory cell model that can store both quantum and classical information. In this paper, we find an interesting new phenomenon that the purely classical memory cell can be super-activated to preserve quantum states, whereas the null memory cell can only be super-activated to encode classical information. Furthermore, necessary and sufficient conditions for this phenomenon are discovered so that the super-activation can be easily checked by examining certain eigenvalues of the quantum memory cell without computing the noiseless subsystems explicitly. In particular, it is found that entangled and separable stationary states are responsible for the super-activation of storing quantum and classical information, respectively. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1708.00700v3-abstract-full').style.display = 'none'; document.getElementById('1708.00700v3-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 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 August, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2017. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.02114">arXiv:1612.02114</a> <span> [<a href="https://arxiv.org/pdf/1612.02114">pdf</a>, <a href="https://arxiv.org/ps/1612.02114">ps</a>, <a href="https://arxiv.org/format/1612.02114">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cryptography and Security">cs.CR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.94.060301">10.1103/PhysRevA.94.060301 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental measurement-device-independent quantum random number generation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Nie%2C+Y">You-Qi Nie</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Hongyi Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</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="1612.02114v1-abstract-short" style="display: inline;"> The randomness from a quantum random number generator (QRNG) relies on the accurate characterization of its devices. However, device imperfections and inaccurate characterizations can result in wrong entropy estimation and bias in practice, which highly affects the genuine randomness generation and may even induce the disappearance of quantum randomness in an extreme case. Here we experimentally d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.02114v1-abstract-full').style.display = 'inline'; document.getElementById('1612.02114v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.02114v1-abstract-full" style="display: none;"> The randomness from a quantum random number generator (QRNG) relies on the accurate characterization of its devices. However, device imperfections and inaccurate characterizations can result in wrong entropy estimation and bias in practice, which highly affects the genuine randomness generation and may even induce the disappearance of quantum randomness in an extreme case. Here we experimentally demonstrate a measurement-device-independent (MDI) QRNG based on time-bin encoding to achieve certified quantum randomness even when the measurement devices are uncharacterized and untrusted. The MDI-QRNG is randomly switched between the regular randomness generation mode and a test mode, in which four quantum states are randomly prepared to perform measurement tomography in real-time. With a clock rate of 25 MHz, the MDI-QRNG generates a final random bit rate of 5.7 Kbps. Such implementation with an all-fiber setup provides an approach to construct a fully-integrated MDI-QRNG with trusted but error-prone devices in practice. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.02114v1-abstract-full').style.display = 'none'; document.getElementById('1612.02114v1-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 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2016. </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, 5 figures, accepted for publication as a Rapid Communication in Physical Review A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 94, 060301(R) (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1611.09982">arXiv:1611.09982</a> <span> [<a href="https://arxiv.org/pdf/1611.09982">pdf</a>, <a href="https://arxiv.org/format/1611.09982">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"> Ground test of satellite constellation based quantum communication </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Yong%2C+H">Hai-Lin Yong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Shentu%2C+G">Guo-Liang Shentu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+D">Dong-Dong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+H">Hui Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+S">Shuang-Qiang Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+W">Wei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+Y">Yun-Hong Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Z">Ze-Hong Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+G">Ge-Sheng Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Pelc%2C+J+S">Jason S. Pelc</a>, <a href="/search/quant-ph?searchtype=author&query=Fejer%2C+M+M">M. M. Fejer</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wen-Zhuo Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wei-Yue Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+J">Ji-Gang Ren</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1611.09982v1-abstract-short" style="display: inline;"> Satellite based quantum communication has been proven as a feasible way to achieve global scale quantum communication network. Very recently, a low-Earth-orbit (LEO) satellite has been launched for this purpose. However, with a single satellite, it takes an inefficient 3-day period to provide the worldwide connectivity. On the other hand, similar to how the Iridium system functions in classic comm… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.09982v1-abstract-full').style.display = 'inline'; document.getElementById('1611.09982v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1611.09982v1-abstract-full" style="display: none;"> Satellite based quantum communication has been proven as a feasible way to achieve global scale quantum communication network. Very recently, a low-Earth-orbit (LEO) satellite has been launched for this purpose. However, with a single satellite, it takes an inefficient 3-day period to provide the worldwide connectivity. On the other hand, similar to how the Iridium system functions in classic communication, satellite constellation (SC) composed of many quantum satellites, could provide global real-time quantum communication. In such a SC, most of the satellites will work in sunlight. Unfortunately, none of previous ground testing experiments could be implemented at daytime. During daytime, the bright sunlight background prohibits quantum communication in transmission over long distances. In this letter, by choosing a working wavelength of 1550 nm and developing free-space single-mode fibre coupling technology and ultralow noise up-conversion single photon detectors, we overcome the noise due to sunlight and demonstrate a 53-km free space quantum key distribution (QKD) in the daytime through a 48-dB loss channel. Our system not only shows the feasibility of satellite based quantum communication in daylight, but also has the ability to naturally adapt to ground fibre optics, representing an essential step towards a SC-based global quantum network. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.09982v1-abstract-full').style.display = 'none'; document.getElementById('1611.09982v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 November, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 2 figures and 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Photonics 11, 509 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.06024">arXiv:1608.06024</a> <span> [<a href="https://arxiv.org/pdf/1608.06024">pdf</a>, <a href="https://arxiv.org/ps/1608.06024">ps</a>, <a href="https://arxiv.org/format/1608.06024">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"> Decomposition of Quantum Markov Chains and Its Applications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Ji Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+Y">Yuan Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Ying%2C+M">Mingsheng Ying</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.06024v2-abstract-short" style="display: inline;"> Markov chains have been widely employed as a fundamental model in the studies of probabilistic and stochastic communicating and concurrent systems. It is well-understood that decomposition techniques play a key role in reachability analysis and model-checking of Markov chains. (Discrete-time) quantum Markov chains have been introduced as a model of quantum communicating systems [1] and also a sema… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.06024v2-abstract-full').style.display = 'inline'; document.getElementById('1608.06024v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.06024v2-abstract-full" style="display: none;"> Markov chains have been widely employed as a fundamental model in the studies of probabilistic and stochastic communicating and concurrent systems. It is well-understood that decomposition techniques play a key role in reachability analysis and model-checking of Markov chains. (Discrete-time) quantum Markov chains have been introduced as a model of quantum communicating systems [1] and also a semantic model of quantum programs [2]. The BSCC (Bottom Strongly Connected Component) and stationary coherence decompositions of quantum Markov chains were introduced in [3, 4, 5]. This paper presents a new decomposition technique, namely periodic decomposition, for quantum Markov chains. We further establish a limit theorem for them. As an application, an algorithm to find a maximum dimensional noiseless subsystem of a quantum communicating system is given using decomposition techniques of quantum Markov chains. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.06024v2-abstract-full').style.display = 'none'; document.getElementById('1608.06024v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 August, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2016. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.02089">arXiv:1603.02089</a> <span> [<a href="https://arxiv.org/pdf/1603.02089">pdf</a>, <a href="https://arxiv.org/format/1603.02089">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.116.240502">10.1103/PhysRevLett.116.240502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of quantum fingerprinting beating the classical limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Si-Jing Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiao-Yan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Li Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1603.02089v1-abstract-short" style="display: inline;"> Quantum communication has historically been at the forefront of advancements, from fundamental tests of quantum physics to utilizing the quantum-mechanical properties of physical systems for practical applications. In the field of communication complexity, quantum communication allows the advantage of an exponential reduction in the information transmitted over classical communication to accomplis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.02089v1-abstract-full').style.display = 'inline'; document.getElementById('1603.02089v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.02089v1-abstract-full" style="display: none;"> Quantum communication has historically been at the forefront of advancements, from fundamental tests of quantum physics to utilizing the quantum-mechanical properties of physical systems for practical applications. In the field of communication complexity, quantum communication allows the advantage of an exponential reduction in the information transmitted over classical communication to accomplish distributed computational tasks. However, to date, demonstrating this advantage in a practical setting continues to be a central challenge. Here, we report an experimental demonstration of a quantum fingerprinting protocol that for the first time surpasses the ultimate classical limit to transmitted information. Ultra-low noise superconducting single-photon detectors and a stable fibre-based Sagnac interferometer are used to implement a quantum fingerprinting system that is capable of transmitting less information than the classical proven lower bound over 20 km standard telecom fibre for input sizes of up to two Gbits. The results pave the way for experimentally exploring the advanced features of quantum communication and open a new window of opportunity for research in communication complexity and testing the foundations of physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.02089v1-abstract-full').style.display = 'none'; document.getElementById('1603.02089v1-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 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 116, 240502 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1505.08142">arXiv:1505.08142</a> <span> [<a href="https://arxiv.org/pdf/1505.08142">pdf</a>, <a href="https://arxiv.org/ps/1505.08142">ps</a>, <a href="https://arxiv.org/format/1505.08142">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.93.030302">10.1103/PhysRevA.93.030302 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental round-robin differential phase-shift quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+H">Hui Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+W">Wei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Y">Yu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1505.08142v1-abstract-short" style="display: inline;"> In conventional quantum key distribution (QKD) protocols, security is guaranteed by estimating the amount of leaked information through monitoring signal disturbance, which, in practice, is generally caused by environmental noise and device imperfections rather than eavesdropping. Such estimation therefore tends to overrate the amount of leaked information in practice, leads to a fundamental thres… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.08142v1-abstract-full').style.display = 'inline'; document.getElementById('1505.08142v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.08142v1-abstract-full" style="display: none;"> In conventional quantum key distribution (QKD) protocols, security is guaranteed by estimating the amount of leaked information through monitoring signal disturbance, which, in practice, is generally caused by environmental noise and device imperfections rather than eavesdropping. Such estimation therefore tends to overrate the amount of leaked information in practice, leads to a fundamental threshold of the bit error rate. The threshold becomes a bottleneck of the development of practical QKD systems. In classical communication, according to Shannon's communication theory, information can transform through a noisy channel even if the background noise is very strong compare to the signal and hence the threshold of the bit error rate tends to 50%. One might wonder whether a QKD scheme can also tolerate error rate as high as 50%. The question is answered affirmatively with the recent work of round-robin differential phase-shift (RRDPS) protocol, which breaks through the fundamental threshold of the bit error rate and indicates another potential direction in the field of quantum cryptography. The key challenge to realize the RRDPS scheme lies on the measurement device, which requires a variable-delay interferometer. The delay needs to be chosen from a set of predetermined values randomly. Such measurement can be realized by switching between many interferometers with different delays at a high speed in accordance with the system repetition rate. The more delay values can be chosen from, the higher error rate can be tolerated. By designing an optical system with multiple switches and employing an active phase stabilization technology, we successfully construct a variable-delay interferometer with 128 actively selectable delays. With this measurement, we experimentally demonstrate the RRDPS QKD protocol and obtain a final key rate of 15.54 bps via a total loss of 18 dB and 8.9% error rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.08142v1-abstract-full').style.display = 'none'; document.getElementById('1505.08142v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">comments are welcome</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 93, 030302 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1505.08076">arXiv:1505.08076</a> <span> [<a href="https://arxiv.org/pdf/1505.08076">pdf</a>, <a href="https://arxiv.org/format/1505.08076">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.114.180502">10.1103/PhysRevLett.114.180502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Passive Round-Robin Differential Phase-Shift Quantum Key Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Z">Zhu Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Shen-Tu%2C+G">Guo-Liang Shen-Tu</a>, <a href="/search/quant-ph?searchtype=author&query=Pelc%2C+J+S">Jason S. Pelc</a>, <a href="/search/quant-ph?searchtype=author&query=Fejer%2C+M+M">M. M. Fejer</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1505.08076v1-abstract-short" style="display: inline;"> In quantum key distribution (QKD), the bit error rate is used to estimate the information leakage and hence determines the amount of privacy amplification --- making the final key private by shortening the key. In general, there exists a threshold of the error rate for each scheme, above which no secure key can be generated. This threshold puts a restriction on the environment noises. For example,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.08076v1-abstract-full').style.display = 'inline'; document.getElementById('1505.08076v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.08076v1-abstract-full" style="display: none;"> In quantum key distribution (QKD), the bit error rate is used to estimate the information leakage and hence determines the amount of privacy amplification --- making the final key private by shortening the key. In general, there exists a threshold of the error rate for each scheme, above which no secure key can be generated. This threshold puts a restriction on the environment noises. For example, a widely used QKD protocol --- BB84 --- cannot tolerate error rates beyond 25%. A new protocol, round-robin differential phase shifted (RRDPS) QKD, essentially removes this restriction and can in principle tolerate more environment disturbance. Here, we propose and experimentally demonstrate a passive RRDPS QKD scheme. In particular, our 500 MHz passive RRDPS QKD system is able to generate a secure key over 50 km with a bit error rate as high as 29%. This scheme should find its applications in noisy environment conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.08076v1-abstract-full').style.display = 'none'; document.getElementById('1505.08076v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 114.180502 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1408.2330">arXiv:1408.2330</a> <span> [<a href="https://arxiv.org/pdf/1408.2330">pdf</a>, <a href="https://arxiv.org/ps/1408.2330">ps</a>, <a href="https://arxiv.org/format/1408.2330">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"> Field Test of Measurement-Device-Independent Quantum Key Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Y">Yan-Lin Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Si-Jing Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Lu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jian Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+D">Dong-Xu Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+H">Hao Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+N">Nan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1408.2330v1-abstract-short" style="display: inline;"> A main type of obstacles of practical applications of quantum key distribution (QKD) network is various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks and thus a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.2330v1-abstract-full').style.display = 'inline'; document.getElementById('1408.2330v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1408.2330v1-abstract-full" style="display: none;"> A main type of obstacles of practical applications of quantum key distribution (QKD) network is various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks and thus a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the laboratory with secure key rates less than 0.1 bps. Besides, they need manual calibration frequently to maintain the system performance. These aspects render these demonstrations far from practicability. Thus, justification is extremely crucial for practical deployment into the field environment. Here, by developing an automatic feedback MDIQKD system operated at a high clock rate, we perform a field test via deployed fiber network of 30 km total length, achieving a 16.9 bps secure key rate. The result lays the foundation for a global quantum network which can shield from all the detection-side attacks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.2330v1-abstract-full').style.display = 'none'; document.getElementById('1408.2330v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 August, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> IEEE J. Sel. T. Quantum Electron. 21, 6600407 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1407.8012">arXiv:1407.8012</a> <span> [<a href="https://arxiv.org/pdf/1407.8012">pdf</a>, <a href="https://arxiv.org/ps/1407.8012">ps</a>, <a href="https://arxiv.org/format/1407.8012">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.113.190501">10.1103/PhysRevLett.113.190501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement-device-independent quantum key distribution over 200 km </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Y">Yan-Lin Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Si-Jing Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+L">Lu Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jian Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Guan%2C+J">Jian-Yu Guan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+D">Dong-Xu Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+H">Hao Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhen Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+N">Nan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</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="1407.8012v1-abstract-short" style="display: inline;"> Measurement-device-independent quantum key distribution (MDIQKD) protocol is immune to all attacks on detection and guarantees the information-theoretical security even with imperfect single photon detectors. Recently, several proof-of-principle demonstrations of MDIQKD have been achieved. Those experiments, although novel, are implemented through limited distance with a key rate less than 0.1 bps… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1407.8012v1-abstract-full').style.display = 'inline'; document.getElementById('1407.8012v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1407.8012v1-abstract-full" style="display: none;"> Measurement-device-independent quantum key distribution (MDIQKD) protocol is immune to all attacks on detection and guarantees the information-theoretical security even with imperfect single photon detectors. Recently, several proof-of-principle demonstrations of MDIQKD have been achieved. Those experiments, although novel, are implemented through limited distance with a key rate less than 0.1 bps. Here, by developing a 75 MHz clock rate fully-automatic and highly-stable system, and superconducting nanowire single photon detectors with detection efficiencies more than 40%, we extend the secure transmission distance of MDIQKD to 200 km and achieve a secure key rate of three orders of magnitude higher. These results pave the way towards a quantum network with measurement-device-independent security. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1407.8012v1-abstract-full').style.display = 'none'; document.getElementById('1407.8012v1-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, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2014. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 113, 190501 (2013) </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/about">About</a></li> <li><a href="https://info.arxiv.org/help">Help</a></li> </ul> </div> <div class="column"> <ul class="nav-spaced"> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>contact arXiv</title><desc>Click here to contact arXiv</desc><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg> <a href="https://info.arxiv.org/help/contact.html"> Contact</a> </li> <li> <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><title>subscribe to arXiv mailings</title><desc>Click here to subscribe</desc><path d="M476 3.2L12.5 270.6c-18.1 10.4-15.8 35.6 2.2 43.2L121 358.4l287.3-253.2c5.5-4.9 13.3 2.6 8.6 8.3L176 407v80.5c0 23.6 28.5 32.9 42.5 15.8L282 426l124.6 52.2c14.2 6 30.4-2.9 33-18.2l72-432C515 7.8 493.3-6.8 476 3.2z"/></svg> <a href="https://info.arxiv.org/help/subscribe"> Subscribe</a> </li> </ul> </div> </div> </div>   <div class="column"> <div class="columns"> <div class="column"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/license/index.html">Copyright</a></li> <li><a href="https://info.arxiv.org/help/policies/privacy_policy.html">Privacy Policy</a></li> </ul> </div> <div class="column sorry-app-links"> <ul class="nav-spaced"> <li><a href="https://info.arxiv.org/help/web_accessibility.html">Web Accessibility Assistance</a></li> <li> <p class="help"> <a class="a11y-main-link" href="https://status.arxiv.org" target="_blank">arXiv Operational Status <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 512" class="icon filter-dark_grey" role="presentation"><path d="M224.3 273l-136 136c-9.4 9.4-24.6 9.4-33.9 0l-22.6-22.6c-9.4-9.4-9.4-24.6 0-33.9l96.4-96.4-96.4-96.4c-9.4-9.4-9.4-24.6 0-33.9L54.3 103c9.4-9.4 24.6-9.4 33.9 0l136 136c9.5 9.4 9.5 24.6.1 34z"/></svg></a><br> Get status notifications via <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/email/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" class="icon filter-black" role="presentation"><path d="M502.3 190.8c3.9-3.1 9.7-.2 9.7 4.7V400c0 26.5-21.5 48-48 48H48c-26.5 0-48-21.5-48-48V195.6c0-5 5.7-7.8 9.7-4.7 22.4 17.4 52.1 39.5 154.1 113.6 21.1 15.4 56.7 47.8 92.2 47.6 35.7.3 72-32.8 92.3-47.6 102-74.1 131.6-96.3 154-113.7zM256 320c23.2.4 56.6-29.2 73.4-41.4 132.7-96.3 142.8-104.7 173.4-128.7 5.8-4.5 9.2-11.5 9.2-18.9v-19c0-26.5-21.5-48-48-48H48C21.5 64 0 85.5 0 112v19c0 7.4 3.4 14.3 9.2 18.9 30.6 23.9 40.7 32.4 173.4 128.7 16.8 12.2 50.2 41.8 73.4 41.4z"/></svg>email</a> or <a class="is-link" href="https://subscribe.sorryapp.com/24846f03/slack/new" target="_blank"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512" class="icon filter-black" role="presentation"><path d="M94.12 315.1c0 25.9-21.16 47.06-47.06 47.06S0 341 0 315.1c0-25.9 21.16-47.06 47.06-47.06h47.06v47.06zm23.72 0c0-25.9 21.16-47.06 47.06-47.06s47.06 21.16 47.06 47.06v117.84c0 25.9-21.16 47.06-47.06 47.06s-47.06-21.16-47.06-47.06V315.1zm47.06-188.98c-25.9 0-47.06-21.16-47.06-47.06S139 32 164.9 32s47.06 21.16 47.06 47.06v47.06H164.9zm0 23.72c25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06H47.06C21.16 243.96 0 222.8 0 196.9s21.16-47.06 47.06-47.06H164.9zm188.98 47.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06s-21.16 47.06-47.06 47.06h-47.06V196.9zm-23.72 0c0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06V79.06c0-25.9 21.16-47.06 47.06-47.06 25.9 0 47.06 21.16 47.06 47.06V196.9zM283.1 385.88c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06-25.9 0-47.06-21.16-47.06-47.06v-47.06h47.06zm0-23.72c-25.9 0-47.06-21.16-47.06-47.06 0-25.9 21.16-47.06 47.06-47.06h117.84c25.9 0 47.06 21.16 47.06 47.06 0 25.9-21.16 47.06-47.06 47.06H283.1z"/></svg>slack</a> </p> </li> </ul> </div> </div> </div>  </div> </footer> <script src="https://static.arxiv.org/static/base/1.0.0a5/js/member_acknowledgement.js"></script> </body> </html>

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