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name="searchtype"><option value="all">All fields</option><option value="title">Title</option><option selected value="author">Author(s)</option><option value="abstract">Abstract</option><option value="comments">Comments</option><option value="journal_ref">Journal reference</option><option value="acm_class">ACM classification</option><option value="msc_class">MSC classification</option><option value="report_num">Report number</option><option value="paper_id">arXiv identifier</option><option value="doi">DOI</option><option value="orcid">ORCID</option><option value="license">License (URI)</option><option value="author_id">arXiv author ID</option><option value="help">Help pages</option><option value="full_text">Full text</option></select> <input id="query" name="query" type="text" value="Wei, K"> <ul id="abstracts"><li><input checked id="abstracts-0" name="abstracts" type="radio" value="show"> <label for="abstracts-0">Show abstracts</label></li><li><input id="abstracts-1" name="abstracts" type="radio" value="hide"> <label for="abstracts-1">Hide abstracts</label></li></ul> </div> <div class="box field is-grouped is-grouped-multiline level-item"> <div class="control"> <span class="select is-small"> <select id="size" name="size"><option value="25">25</option><option selected value="50">50</option><option value="100">100</option><option value="200">200</option></select> </span> <label for="size">results per page</label>. </div> <div class="control"> <label for="order">Sort results by</label> <span class="select is-small"> <select id="order" name="order"><option selected value="-announced_date_first">Announcement date (newest first)</option><option value="announced_date_first">Announcement date (oldest first)</option><option value="-submitted_date">Submission date (newest first)</option><option value="submitted_date">Submission date (oldest first)</option><option value="">Relevance</option></select> </span> </div> <div class="control"> <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/2409.15665">arXiv:2409.15665</a> <span> [<a href="https://arxiv.org/pdf/2409.15665">pdf</a>, <a href="https://arxiv.org/format/2409.15665">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dynamically Optimized Nonadiabatic Holonomic Quantum Computation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Hai Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wanchun Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Tao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chengxian Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.15665v1-abstract-short" style="display: inline;"> Nonadiabatic holonomic quantum computation (NHQC) is one of the promising approaches to realizing fault-tolerant quantum computation. However, due to the imperfect control in the experimental environments, the holonomic gate still needs to be further improved. Here, we propose a dynamically optimized NHQC (OPNHQC) scheme based on dynamically corrected gate technique. The scheme is implemented by c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.15665v1-abstract-full').style.display = 'inline'; document.getElementById('2409.15665v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.15665v1-abstract-full" style="display: none;"> Nonadiabatic holonomic quantum computation (NHQC) is one of the promising approaches to realizing fault-tolerant quantum computation. However, due to the imperfect control in the experimental environments, the holonomic gate still needs to be further improved. Here, we propose a dynamically optimized NHQC (OPNHQC) scheme based on dynamically corrected gate technique. The scheme is implemented by carefully designing a sequence of elementary pulses to fulfill cyclic evolution, while the dynamical phase is not accumulated. In this way, the constructed holonomic gate is immune to the error. It is found that our scheme can correct the $X$ error up to fourth order. In addition, combining with the DFS encoding our scheme can be immune to both the $X$ and $Z$ errors. Therefore, our proposed scheme offers a prospective way to the realization of scalable fault-tolerant holonomic quantum computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.15665v1-abstract-full').style.display = 'none'; document.getElementById('2409.15665v1-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.00601">arXiv:2409.00601</a> <span> [<a href="https://arxiv.org/pdf/2409.00601">pdf</a>, <a href="https://arxiv.org/format/2409.00601">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"> Geometric two-qubit gates in silicon-based double quantum dots </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yong-Yang Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chengxian Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.00601v1-abstract-short" style="display: inline;"> Achieving high-fidelity two-qubit gates is crucial for spin qubits in silicon double quantum dots. However, the two-qubit gates in experiments are easily suffered from charge noise, which is still a key challenge. Geometric gates which implement gate operations employing pure geometric phase are believed to be a powerful way to realize robust control. In this work, we theoretically propose feasibl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.00601v1-abstract-full').style.display = 'inline'; document.getElementById('2409.00601v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.00601v1-abstract-full" style="display: none;"> Achieving high-fidelity two-qubit gates is crucial for spin qubits in silicon double quantum dots. However, the two-qubit gates in experiments are easily suffered from charge noise, which is still a key challenge. Geometric gates which implement gate operations employing pure geometric phase are believed to be a powerful way to realize robust control. In this work, we theoretically propose feasible strategy to implement geometric two-qubit gates for silicon-based spin qubits considering experimental control environments. By working in the suitable region where the local magnetic field gradient is much larger than the exchange interaction, we are able to implement entangling and non-entangling geometric gates via analytical and numerical methods. It is found that the implemented geometric gates can obtain fidelities surpassing 99\% for the noise level related to the experiments. Also, they can outperform the dynamical opertations. Our work paves a way to implement high-fidelity geometric gate for spin qubits in silicon. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.00601v1-abstract-full').style.display = 'none'; document.getElementById('2409.00601v1-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.07513">arXiv:2407.07513</a> <span> [<a href="https://arxiv.org/pdf/2407.07513">pdf</a>, <a href="https://arxiv.org/format/2407.07513">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> High-rate quantum digital signatures network with integrated silicon photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yongqiang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bing-Hong Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+X">Xin Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+X">Xiao-Yu Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Zhengeng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+F">Feng Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+X">Xi Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.07513v1-abstract-short" style="display: inline;"> The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and non-repudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07513v1-abstract-full').style.display = 'inline'; document.getElementById('2407.07513v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.07513v1-abstract-full" style="display: none;"> The development of quantum networks is paramount towards practical and secure communications. Quantum digital signatures (QDS) offer an information-theoretically secure solution for ensuring data integrity, authenticity, and non-repudiation, rapidly growing from proof-of-concept to robust demonstrations. However, previous QDS systems relied on expensive and bulky optical equipment, limiting large-scale deployment and reconfigurable networking construction. Here, we introduce and verify a chip-based QDS network, placing the complicated and expensive measurement devices in the central relay while each user needs only a low-cost transmitter. We demonstrate the network with a three-node setup using an integrated encoder chip and decoder chip. By developing a 1-decoy-state one-time universal hash-QDS protocol, we achieve a maximum signature rate of 0.0414 times per second for a 1 Mbit file over fiber distances up to 200 km, surpassing all current state-of-the-art QDS experiments. This study validates the feasibility of chip-based QDS, paving the way for large-scale deployment and integration with existing fiber infrastructure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.07513v1-abstract-full').style.display = 'none'; document.getElementById('2407.07513v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 6 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.03980">arXiv:2407.03980</a> <span> [<a href="https://arxiv.org/pdf/2407.03980">pdf</a>, <a href="https://arxiv.org/format/2407.03980">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"> Practical asynchronous measurement-device-independent quantum key distribution with advantage distillation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Luo%2C+D">Di Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+K">Kaibiao Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.03980v1-abstract-short" style="display: inline;"> The advantage distillation (AD) method has proven effective in improving the performance of quantum key distribution (QKD). In this paper, we introduce the AD method into a recently proposed asynchronous measurement-device-independent (AMDI) QKD protocol, taking finite-key effects into account. Simulation results show that the AD method significantly enhances AMDIQKD, e.g., extending the transmiss… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03980v1-abstract-full').style.display = 'inline'; document.getElementById('2407.03980v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.03980v1-abstract-full" style="display: none;"> The advantage distillation (AD) method has proven effective in improving the performance of quantum key distribution (QKD). In this paper, we introduce the AD method into a recently proposed asynchronous measurement-device-independent (AMDI) QKD protocol, taking finite-key effects into account. Simulation results show that the AD method significantly enhances AMDIQKD, e.g., extending the transmission distance by 16 km with a total pulse count of N = 7.24*10^13, and enables AMDI-QKD, previously unable to generate keys, to generate keys with a misalignment error rate of 10%. As the AD method can be directly integrated into the current system through refined post-processing, our results facilitate the practical implementation of AMDI-QKD in various applications, particularly in scenarios with high channel losses and misalignment errors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.03980v1-abstract-full').style.display = 'none'; document.getElementById('2407.03980v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.16558">arXiv:2405.16558</a> <span> [<a href="https://arxiv.org/pdf/2405.16558">pdf</a>, <a href="https://arxiv.org/format/2405.16558">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Experimental Refrence-Frame-Independent Quantum Key Distribution over 250 km of Optical Fiber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+D">Di Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Z">Zhicheng Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+S">Shizhuo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.16558v1-abstract-short" style="display: inline;"> The reference-frame-independent quantum key distribution (RFI-QKD) protocol enables QKD systems to function effectively despite slowly varying reference frames, offering a distinct advantage in practical scenarios, particularly in mobile platforms. In this study, we successfully distribute secure key bits over a 250 km optical fiber distance by developing an RFI-QKD system with a repetition rate o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.16558v1-abstract-full').style.display = 'inline'; document.getElementById('2405.16558v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.16558v1-abstract-full" style="display: none;"> The reference-frame-independent quantum key distribution (RFI-QKD) protocol enables QKD systems to function effectively despite slowly varying reference frames, offering a distinct advantage in practical scenarios, particularly in mobile platforms. In this study, we successfully distribute secure key bits over a 250 km optical fiber distance by developing an RFI-QKD system with a repetition rate of 150 MHz. Benefiting from high repetition rate, we achieve a finite-key secret key rate of 49.65 bit/s at a distance of 200 km, which is more than three times higher than state-of-the-art systems. Our work dramatically extends the transmission distance and enhances the secret key rate of RFI-QKD, significantly promoting its practical application. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.16558v1-abstract-full').style.display = 'none'; document.getElementById('2405.16558v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages,4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.17011">arXiv:2312.17011</a> <span> [<a href="https://arxiv.org/pdf/2312.17011">pdf</a>, <a href="https://arxiv.org/format/2312.17011">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"> Source-independent quantum random number generators with integrated silicon photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yongqiang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+X">Xin Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Zhengeng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+X">Xiaoran Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+X">Xi Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.17011v1-abstract-short" style="display: inline;"> Random numbers play a crucial role in numerous scientific applications. Source-independent quantum random number generators (SI-QRNGs) can offer true randomness by leveraging the fundamental principles of quantum mechanics, eliminating the need for a trusted source. Silicon photonics shows great promise for QRNG due to its benefits in miniaturization, cost-effective device manufacturing, and compa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.17011v1-abstract-full').style.display = 'inline'; document.getElementById('2312.17011v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.17011v1-abstract-full" style="display: none;"> Random numbers play a crucial role in numerous scientific applications. Source-independent quantum random number generators (SI-QRNGs) can offer true randomness by leveraging the fundamental principles of quantum mechanics, eliminating the need for a trusted source. Silicon photonics shows great promise for QRNG due to its benefits in miniaturization, cost-effective device manufacturing, and compatibility with CMOS microelectronics. In this study, we experimentally demonstrate a silicon-based discrete variable SI-QRNG. Using a well-calibrated chip and an optimized parameter strategy, we achieve a record-breaking random number generation rate of 7.9 Mbits/s. Our research paves the way for integrated SI-QRNGs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.17011v1-abstract-full').style.display = 'none'; document.getElementById('2312.17011v1-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Comments are welcomed</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.15399">arXiv:2312.15399</a> <span> [<a href="https://arxiv.org/pdf/2312.15399">pdf</a>, <a href="https://arxiv.org/format/2312.15399">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Improved security bounds against the Trojan-Horse attack in decoy-state quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zijian Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+B">Bingbing Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chengxian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+H">Hong-Bo Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.15399v1-abstract-short" style="display: inline;"> In a quantum Trojan-horse attack (THA), eavesdroppers learn encoded information by injecting bright light into encoded or decoded devices of quantum key distribution (QKD) systems. These attacks severely compromise the security of non-isolated systems. Thus, analytical security bound was derived in previous studies. However, these studies achieved poor performance unless the devices were strongly… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.15399v1-abstract-full').style.display = 'inline'; document.getElementById('2312.15399v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.15399v1-abstract-full" style="display: none;"> In a quantum Trojan-horse attack (THA), eavesdroppers learn encoded information by injecting bright light into encoded or decoded devices of quantum key distribution (QKD) systems. These attacks severely compromise the security of non-isolated systems. Thus, analytical security bound was derived in previous studies. However, these studies achieved poor performance unless the devices were strongly isolated. Here, we present a numerical method for achieving improved security bound for a decoy-state QKD system under THAs. The developed method takes advantage of the well-established numerical framework and significantly outperforms previous analytical bounds regarding the achievable final key and secure transmitted distance. The results provide a new tool for investigating the efficient security bounds of THA in practical decoy-state QKD systems. This study constitutes an important step toward securing QKD with real-life components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.15399v1-abstract-full').style.display = 'none'; document.getElementById('2312.15399v1-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Comments are welecomed</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.12146">arXiv:2310.12146</a> <span> [<a href="https://arxiv.org/pdf/2310.12146">pdf</a>, <a href="https://arxiv.org/format/2310.12146">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/PRXQuantum.5.020338">10.1103/PRXQuantum.5.020338 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Native two-qubit gates in fixed-coupling, fixed-frequency transmons beyond cross-resonance interaction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken Xuan Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Lauer%2C+I">Isaac Lauer</a>, <a href="/search/quant-ph?searchtype=author&query=Pritchett%2C+E">Emily Pritchett</a>, <a href="/search/quant-ph?searchtype=author&query=Shanks%2C+W">William Shanks</a>, <a href="/search/quant-ph?searchtype=author&query=McKay%2C+D+C">David C. McKay</a>, <a href="/search/quant-ph?searchtype=author&query=Javadi-Abhari%2C+A">Ali Javadi-Abhari</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="2310.12146v2-abstract-short" style="display: inline;"> Fixed-frequency superconducting qubits demonstrate remarkable success as platforms for stable and scalable quantum computing. Cross-resonance gates have been the workhorse of fixed-coupling, fixed-frequency superconducting processors, leveraging the entanglement generated by driving one qubit resonantly with a neighbor's frequency to achieve high-fidelity, universal CNOTs. Here, we use on-resonant… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12146v2-abstract-full').style.display = 'inline'; document.getElementById('2310.12146v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.12146v2-abstract-full" style="display: none;"> Fixed-frequency superconducting qubits demonstrate remarkable success as platforms for stable and scalable quantum computing. Cross-resonance gates have been the workhorse of fixed-coupling, fixed-frequency superconducting processors, leveraging the entanglement generated by driving one qubit resonantly with a neighbor's frequency to achieve high-fidelity, universal CNOTs. Here, we use on-resonant and off-resonant microwave drives to go beyond cross-resonance, realizing natively interesting two-qubit gates that are not equivalent to CNOTs. In particular, we implement and benchmark native ISWAP, SWAP, $\sqrt{\text{ISWAP}}$, and BSWAP gates. Furthermore, we apply these techniques for an efficient construction of the B-gate: a perfect entangler from which any two-qubit gate can be reached in only two applications. We show these native two-qubit gates are better than their counterparts compiled from cross-resonance gates. We elucidate the resonance conditions required to drive each two-qubit gate and provide a novel frame tracking technique to implement them in Qiskit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.12146v2-abstract-full').style.display = 'none'; document.getElementById('2310.12146v2-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">added new section, more data, improved presentation</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 5, 020338 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.16600">arXiv:2309.16600</a> <span> [<a href="https://arxiv.org/pdf/2309.16600">pdf</a>, <a href="https://arxiv.org/format/2309.16600">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s42005-024-01713-7">10.1038/s42005-024-01713-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraining Ultralight Dark Matter through an Accelerated Resonant Search </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zitong Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaolin Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yuxuan He</a>, <a href="/search/quant-ph?searchtype=author&query=Heng%2C+X">Xing Heng</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+X">Xiaofei Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Ai%2C+T">Tengyu Ai</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+J">Jian Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Ji%2C+W">Wei Ji</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jia Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiao-Ping Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Budker%2C+D">Dmitry Budker</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="2309.16600v2-abstract-short" style="display: inline;"> Experiments aimed at detecting ultralight dark matter typically rely on resonant effects, which are sensitive to the dark matter mass that matches the resonance frequency. In this study, we investigate the nucleon couplings of ultralight axion dark matter using a magnetometer operating in a nuclear magnetic resonance (NMR) mode. Our approach involves the use of a $^{21}$Ne spin-based sensor, which… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.16600v2-abstract-full').style.display = 'inline'; document.getElementById('2309.16600v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.16600v2-abstract-full" style="display: none;"> Experiments aimed at detecting ultralight dark matter typically rely on resonant effects, which are sensitive to the dark matter mass that matches the resonance frequency. In this study, we investigate the nucleon couplings of ultralight axion dark matter using a magnetometer operating in a nuclear magnetic resonance (NMR) mode. Our approach involves the use of a $^{21}$Ne spin-based sensor, which features the lowest nuclear magnetic moment among noble-gas spins. This configuration allows us to achieve an ultrahigh sensitivity of 0.73 fT/Hz$^{1/2}$ at around 5 Hz, corresponding to energy resolution of approximately 1.5$\times 10^{-23}\,\rm{eV/Hz^{1/2}}$. Our analysis reveals that under certain conditions it is beneficial to scan the frequency with steps significantly larger than the resonance width. The analytical results are in agreement with experimental data and the scan strategy is potentially applicable to other resonant searches. Further, our study establishes stringent constraints on axion-like particles (ALP) in the 4.5--15.5 Hz Compton-frequency range coupling to neutrons and protons, improving on prior work by several-fold. Within a band around 4.6--6.6 Hz and around 7.5 Hz, our laboratory findings surpass astrophysical limits derived from neutron-star cooling. Hence, we demonstrate an accelerated resonance search for ultralight dark matter, achieving an approximately 30-fold increase in scanning step while maintaining competitive sensitivity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.16600v2-abstract-full').style.display = 'none'; document.getElementById('2309.16600v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 11 figures, accepted by Communications Physics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.14385">arXiv:2308.14385</a> <span> [<a href="https://arxiv.org/pdf/2308.14385">pdf</a>, <a href="https://arxiv.org/format/2308.14385">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1007/s11433-023-2302-8">10.1007/s11433-023-2302-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A cost-efficient quantum access network with qubit-based synchronization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+T">Tingting Luo</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+W">Wenjie He</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.14385v3-abstract-short" style="display: inline;"> Quantum Key Distribution (QKD) is a physical layer encryption technique that enables two distant parties to exchange secure keys with information-theoretic security. In the last two decades, QKD has transitioned from laboratory research to real-world applications, including multi-user quantum access networks (QANs). This network structure allows users to share a single-photon detector at a network… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.14385v3-abstract-full').style.display = 'inline'; document.getElementById('2308.14385v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.14385v3-abstract-full" style="display: none;"> Quantum Key Distribution (QKD) is a physical layer encryption technique that enables two distant parties to exchange secure keys with information-theoretic security. In the last two decades, QKD has transitioned from laboratory research to real-world applications, including multi-user quantum access networks (QANs). This network structure allows users to share a single-photon detector at a network node through time-division multiplexing, thereby significantly reducing the network cost. However, current QAN implementations require additional hardware for auxiliary tasks such as time synchronization. To address this issue, we propose a cost-efficient QAN that uses qubit-based synchronization. In this approach, the transmitted qubits facilitate time synchronization, eliminating the need for additional synchronization hardware. We tested our scheme by implementing a network for two users and successfully achieved average secure key rates of $53.84$ kbps and $71.90$ kbps for each user over a 50-km commercial fiber spool. In addition, we investigated the capacity of the access network under cross-talk and loss conditions. The simulation results demonstrate that this scheme can support a QAN with 64 users with key rates up to 1070~bps. Our work provides a feasible and cost-effective way to implement a multi-user QKD network, further promoting the widespread application of QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.14385v3-abstract-full').style.display = 'none'; document.getElementById('2308.14385v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 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">Comments are welcomed. Accepted by Science China-Physics Mechanics & Astronomy</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.13154">arXiv:2308.13154</a> <span> [<a href="https://arxiv.org/pdf/2308.13154">pdf</a>, <a href="https://arxiv.org/format/2308.13154">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"> Qubit-based distributed frame synchronization for quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+S">Shuyi Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.13154v2-abstract-short" style="display: inline;"> Quantum key distribution (QKD) is a method that enables two remote parties to share a secure key string. Clock synchronization between two parties is a crucial step in the normal operation of QKD. Qubit-based synchronization can achieve clock synchronization by transmitting quantum states between two remote parties, eliminating the necessity for hardware synchronization and thereby greatly reducin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.13154v2-abstract-full').style.display = 'inline'; document.getElementById('2308.13154v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.13154v2-abstract-full" style="display: none;"> Quantum key distribution (QKD) is a method that enables two remote parties to share a secure key string. Clock synchronization between two parties is a crucial step in the normal operation of QKD. Qubit-based synchronization can achieve clock synchronization by transmitting quantum states between two remote parties, eliminating the necessity for hardware synchronization and thereby greatly reducing the hardware requirements of a QKD system. Nonetheless, classical qubit-based synchronization exhibits poor performance in continuous and high-loss systems, hindering its wide applicability in various scenarios. We propose a qubit-based distributed frame synchronization method that can achieve time recovery in a continuously running system and resist higher losses. Experimental results show that the proposed method outperforms the advanced qubit-based synchronization method Qubit4Sync in a continuously running system. We believe our method is applicable to a broad range of QKD scenarios, including drone-based QKD and quantum network construction. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.13154v2-abstract-full').style.display = 'none'; document.getElementById('2308.13154v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 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">Any comments are welcomed</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.08039">arXiv:2306.08039</a> <span> [<a href="https://arxiv.org/pdf/2306.08039">pdf</a>, <a href="https://arxiv.org/format/2306.08039">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Physics - Phenomenology">hep-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Dark matter search with a strongly-coupled hybrid spin system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zitong Xu</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y">Yuxuan He</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiaolin Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Heng%2C+X">Xing Heng</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+X">Xiaofei Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Quan%2C+W">Wei Quan</a>, <a href="/search/quant-ph?searchtype=author&query=Ji%2C+W">Wei Ji</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jia Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiaoping Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+J">Jiancheng Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Budker%2C+D">Dmitry Budker</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.08039v1-abstract-short" style="display: inline;"> Observational evidence suggests the existence of dark matter (DM), which comprises approximately $84.4\%$ of matter in the universe. Recent advances in tabletop quantum sensor technology have enabled searches for nongravitational interactions of DM. Our experiment named ChangE utilizes Coupled Hot Atom eNsembles to search for liGht dark mattEr and new physics. We identify a strongly-coupled hybrid… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08039v1-abstract-full').style.display = 'inline'; document.getElementById('2306.08039v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.08039v1-abstract-full" style="display: none;"> Observational evidence suggests the existence of dark matter (DM), which comprises approximately $84.4\%$ of matter in the universe. Recent advances in tabletop quantum sensor technology have enabled searches for nongravitational interactions of DM. Our experiment named ChangE utilizes Coupled Hot Atom eNsembles to search for liGht dark mattEr and new physics. We identify a strongly-coupled hybrid spin-resonance (HSR) regime that enhances the bandwidth of $^{21}$Ne nuclear spin by three orders of magnitude while maintaining high sensitivity. In combination with a self-compensating mode (SC) for low frequencies, we present a comprehensive broadband search for axion-like dark matter with Compton frequencies in the range of $[0.01, 1000]$ Hz. We set new constraints on the DM interactions with neutrons and protons, accounting for the stochastic effect. For the axion-neutron coupling, our results reach a low value of $|g_{ann}|\le 3\times 10^{-10}$ in the frequency range $[0.02 , 4]$ Hz surpassing astrophysical limits and provide the strongest laboratory constraints in the $[10, 100]$ Hz range. For the axion-proton coupling, we offer the best terrestrial constraints for the frequency below 100 Hz. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08039v1-abstract-full').style.display = 'none'; document.getElementById('2306.08039v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.06564">arXiv:2306.06564</a> <span>  </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"> Guarding Quantum Key Distribution with integrated Magnetic-free Nonreciprocal Structures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qiang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yinming Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+T">Tingting Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Geng%2C+M">Minming Geng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.06564v2-abstract-short" style="display: inline;"> Inserting nonreciprocal devices at the doorways of Alice and Bob is a widely recognized countermeasure against quantum hacking attacks in quantum key distribution (QKD) systems. However, traditional integrated nonreciprocal devices, which are typically based on magneto-optical effects, face challenges in compatibility with current semiconductor integration technology. As a result, earlier chip-bas… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06564v2-abstract-full').style.display = 'inline'; document.getElementById('2306.06564v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.06564v2-abstract-full" style="display: none;"> Inserting nonreciprocal devices at the doorways of Alice and Bob is a widely recognized countermeasure against quantum hacking attacks in quantum key distribution (QKD) systems. However, traditional integrated nonreciprocal devices, which are typically based on magneto-optical effects, face challenges in compatibility with current semiconductor integration technology. As a result, earlier chip-based QKD systems were unable to integrate nonreciprocal components and were vulnerable to injecting-type attacks. Based on the actual parameters of SOI integration, we employed the inverse design with the direct binary search algorithm to construct several magnetic-free nonreciprocal devices, facilitating their integration into chip-based QKD systems while meeting various chip configuration design requirements. The designed devices have sizes of only a few square micrometers, yet the quasi-isolator can achieve an isolation level exceeding 27 dB. To demonstrate their practical utility in QKD, we employed the designed devices to safeguard the QKD system against Trojan-horse attacks. The simulation results demonstrate that our proposed devices effectively secure the BB84 and measure-device-independent QKD systems against Trojan-horse attacks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.06564v2-abstract-full').style.display = 'none'; document.getElementById('2306.06564v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">We have found that the presented structure is a mode convertor which is suitable for guarding quantum key ditribution</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.03534">arXiv:2304.03534</a> <span> [<a href="https://arxiv.org/pdf/2304.03534">pdf</a>, <a href="https://arxiv.org/format/2304.03534">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.107.062613">10.1103/PhysRevA.107.062613 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Mode-pairing quantum key distribution with advantage distillation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+D">Di Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.03534v3-abstract-short" style="display: inline;"> Mode-pairing quantum key distribution (MP-QKD) is an easy-to-implement scheme that transcends the Pirandola--Laurenza--Ottaviani--Banchi bound without using quantum repeaters. In this paper, we present an improvement of the performance of MP-QKD using an advantage distillation method. The simulation results demonstrate that the proposed scheme extends the transmission distance significantly with a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.03534v3-abstract-full').style.display = 'inline'; document.getElementById('2304.03534v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.03534v3-abstract-full" style="display: none;"> Mode-pairing quantum key distribution (MP-QKD) is an easy-to-implement scheme that transcends the Pirandola--Laurenza--Ottaviani--Banchi bound without using quantum repeaters. In this paper, we present an improvement of the performance of MP-QKD using an advantage distillation method. The simulation results demonstrate that the proposed scheme extends the transmission distance significantly with a channel loss exceeding 7.6 dB. Moreover, the scheme tolerates a maximum quantum bit error rate of 8.9%, which is nearly twice that of the original MP-QKD. In particular, as the system misalignment error increases, the expandable distance of the proposed scheme also increases. The proposed system is expected to promote the practical implementation of MP-QKD in a wide range of applications, particularly in scenarios involving high channel losses and system errors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.03534v3-abstract-full').style.display = 'none'; document.getElementById('2304.03534v3-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 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.10881">arXiv:2302.10881</a> <span> [<a href="https://arxiv.org/pdf/2302.10881">pdf</a>, <a href="https://arxiv.org/format/2302.10881">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.21.024018">10.1103/PhysRevApplied.21.024018 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterizing non-Markovian Off-Resonant Errors in Quantum Gates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken Xuan Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Pritchett%2C+E">Emily Pritchett</a>, <a href="/search/quant-ph?searchtype=author&query=Zajac%2C+D+M">David M. Zajac</a>, <a href="/search/quant-ph?searchtype=author&query=McKay%2C+D+C">David C. McKay</a>, <a href="/search/quant-ph?searchtype=author&query=Merkel%2C+S">Seth Merkel</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.10881v2-abstract-short" style="display: inline;"> As quantum gates improve, it becomes increasingly difficult to characterize the remaining errors. Here we describe a class of coherent non-Markovian errors -- excitations due to an off-resonant drive -- that occur naturally in quantum devices that use time-dependent fields to generate gate operations. We show how these errors are mischaracterized using standard Quantum Computer Verification and Va… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.10881v2-abstract-full').style.display = 'inline'; document.getElementById('2302.10881v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.10881v2-abstract-full" style="display: none;"> As quantum gates improve, it becomes increasingly difficult to characterize the remaining errors. Here we describe a class of coherent non-Markovian errors -- excitations due to an off-resonant drive -- that occur naturally in quantum devices that use time-dependent fields to generate gate operations. We show how these errors are mischaracterized using standard Quantum Computer Verification and Validation (QCVV) techniques that rely on Markovianity and are therefore often overlooked or assumed to be incoherent. We first demonstrate off-resonant errors within a simple toy model of Z-gates created by the AC Stark effect, then show how off-resonant errors manifest in all gates driven on a fixed-frequency transmon architecture, a prominent example being incidental cross-resonance interaction driven during single-qubit gates. Furthermore, the same methodology can access the errors caused by two-level systems (TLS), showing evidence of coherent, off-resonant interactions with subsystems that are not intentional qubits. While we explore these results and their impact on gate error for fixed-frequency devices, we note that off-resonant excitations potentially limit any architectures that use frequency selectivity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.10881v2-abstract-full').style.display = 'none'; document.getElementById('2302.10881v2-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">fixed typos, updated references, and improved explanations</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 21, 024018 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.12980">arXiv:2212.12980</a> <span> [<a href="https://arxiv.org/pdf/2212.12980">pdf</a>, <a href="https://arxiv.org/format/2212.12980">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"> Resource-efficient quantum key distribution with integrated silicon photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yongqiang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+X">Xin Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Zhengeng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+X">Xi Xiao</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.12980v2-abstract-short" style="display: inline;"> Integrated photonics provides a promising platform for quantum key distribution (QKD) system in terms of miniaturization, robustness and scalability. Tremendous QKD works based on integrated photonics have been reported. Nonetheless, most current chip-based QKD implementations require additional off-chip hardware to demodulate quantum states or perform auxiliary tasks such as time synchronization… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.12980v2-abstract-full').style.display = 'inline'; document.getElementById('2212.12980v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.12980v2-abstract-full" style="display: none;"> Integrated photonics provides a promising platform for quantum key distribution (QKD) system in terms of miniaturization, robustness and scalability. Tremendous QKD works based on integrated photonics have been reported. Nonetheless, most current chip-based QKD implementations require additional off-chip hardware to demodulate quantum states or perform auxiliary tasks such as time synchronization and polarization basis tracking. Here, we report a demonstration of resource-efficient chip-based BB84 QKD with a silicon-based encoder and decoder. In our scheme, the time synchronization and polarization compensation are implemented relying on the preparation and measurement of the quantum states generated by on-chip devices, thus no need additional hardware. The experimental tests show that our scheme is highly stable with a low intrinsic QBER of $0.50\pm 0.02\%$ in a 6-h continuous run. Furthermore, over a commercial fiber channel up to 150 km, the system enables realizing secure key distribution at a rate of 866 bps. Our demonstration paves the way for low-cost, wafer-scale manufactured QKD system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.12980v2-abstract-full').style.display = 'none'; document.getElementById('2212.12980v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">comments are welcomed. Accepted by Photonics Research</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.04019">arXiv:2212.04019</a> <span> [<a href="https://arxiv.org/pdf/2212.04019">pdf</a>, <a href="https://arxiv.org/format/2212.04019">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"> Silicon-based decoder for polarization-encoding quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yongqiang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+X">Xun Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+X">Xin Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Z">Zhengeng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+Y">Yi Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Xiao%2C+X">Xi Xiao</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.04019v1-abstract-short" style="display: inline;"> Silicon-based polarization-encoding quantum key distribution (QKD) has been widely studied, owing to its low cost and robustness. However, prior studies have utilized off-chip devices to demodulate the quantum states or perform polarization compensation, given the difficulty of fabricating polarized independent components on the chip. In this paper, we propose a fully chip-based decoder for polari… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.04019v1-abstract-full').style.display = 'inline'; document.getElementById('2212.04019v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.04019v1-abstract-full" style="display: none;"> Silicon-based polarization-encoding quantum key distribution (QKD) has been widely studied, owing to its low cost and robustness. However, prior studies have utilized off-chip devices to demodulate the quantum states or perform polarization compensation, given the difficulty of fabricating polarized independent components on the chip. In this paper, we propose a fully chip-based decoder for polarization-encoding QKD. The chip realizes a polarization state analyzer and compensates for the BB84 protocol without requiring additional hardware. It is based on a polarization-to-path conversion method that uses a polarization splitter-rotator. The chip was fabricated using a standard silicon photonics foundry; it has a compact design and is suitable for mass production. In the experimental stability test, an average quantum bit error rate of $0.56\%$ was achieved through continuous operation for 10 h without any polarization feedback. Furthermore, using the developed feedback algorithm, the chip enabled the automatic compensation of the fiber polarization drift, which was emulated by a random fiber polarization scrambler. In the case of the QKD demonstration, we obtained a finite-key secret rate of 240 bps over a fiber spool of 100 km. This study represents an important step toward the integrated, practical, and large-scale deployment of QKD systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.04019v1-abstract-full').style.display = 'none'; document.getElementById('2212.04019v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">11 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.09027">arXiv:2210.09027</a> <span> [<a href="https://arxiv.org/pdf/2210.09027">pdf</a>, <a href="https://arxiv.org/format/2210.09027">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.063201">10.1103/PhysRevLett.130.063201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultrasensitive atomic comagnetometer with enhanced nuclear spin coherence </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+T">Tian Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+X">Xiujie Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zitong Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+C">Chang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Q">Qian Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Wickenbrock%2C+A">Arne Wickenbrock</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Y">Yanhui Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Ji%2C+W">Wei Ji</a>, <a href="/search/quant-ph?searchtype=author&query=Budker%2C+D">Dmitry Budker</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="2210.09027v1-abstract-short" style="display: inline;"> Achieving high energy resolution in spin systems is important for fundamental physics research and precision measurements, with alkali-noble-gas comagnetometers being among the best available sensors. We found a new relaxation mechanism in such devices, the gradient of the Fermi-contact-interaction field that dominates the relaxation of hyperpolarized nuclear spins. We report on precise control ov… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.09027v1-abstract-full').style.display = 'inline'; document.getElementById('2210.09027v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.09027v1-abstract-full" style="display: none;"> Achieving high energy resolution in spin systems is important for fundamental physics research and precision measurements, with alkali-noble-gas comagnetometers being among the best available sensors. We found a new relaxation mechanism in such devices, the gradient of the Fermi-contact-interaction field that dominates the relaxation of hyperpolarized nuclear spins. We report on precise control over spin distribution, demonstrating a tenfold increase of nuclear spin hyperpolarization and transverse coherence time with optimal hybrid optical pumping. Operating in the self-compensation regime, our $^{21}$Ne-Rb-K comagnetometer achieves an ultrahigh inertial rotation sensitivity of $3\times10^{-8}$\,rad/s/Hz$^{1/2}$ in the frequency range from 0.2 to 1.0 Hz, which is equivalent to the energy resolution of $3.1\times 10^{-23}$\,eV/Hz$^{1/2}$. We propose to use this comagnetometer to search for exotic spin-dependent interactions involving proton and neutron spins. The projected sensitivity surpasses the previous experimental and astrophysical limits by more than four orders of magnitude. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.09027v1-abstract-full').style.display = 'none'; document.getElementById('2210.09027v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.03894">arXiv:2208.03894</a> <span> [<a href="https://arxiv.org/pdf/2208.03894">pdf</a>, <a href="https://arxiv.org/format/2208.03894">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.106.022614">10.1103/PhysRevA.106.022614 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental study of secure quantum key distribution with source and detection imperfections </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Z">Zihao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+W">Wenjie He</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chengxian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shihai Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.03894v1-abstract-short" style="display: inline;"> The quantum key distribution (QKD), guaranteed by the principle of quantum physics, is a promising solution for future secure information and communication technology. However, device imperfections compromise the security of real-life QKD systems, restricting the wide deployment of QKD. This study reports a decoy-state BB84 QKD experiment that considers both source and detection imperfections. In… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.03894v1-abstract-full').style.display = 'inline'; document.getElementById('2208.03894v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.03894v1-abstract-full" style="display: none;"> The quantum key distribution (QKD), guaranteed by the principle of quantum physics, is a promising solution for future secure information and communication technology. However, device imperfections compromise the security of real-life QKD systems, restricting the wide deployment of QKD. This study reports a decoy-state BB84 QKD experiment that considers both source and detection imperfections. In particular, we achieved a rigorous finite-key security bound over fiber links of up to 75 km by applying a systematic performance analysis. Furthermore, our study considers more device imperfections than most previous experiments, and the proposed theory can be extended to other discrete-variable QKD systems. These features constitute a crucial step toward securing QKD with imperfect practical devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.03894v1-abstract-full').style.display = 'none'; document.getElementById('2208.03894v1-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 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">11 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.00658">arXiv:2208.00658</a> <span> [<a href="https://arxiv.org/pdf/2208.00658">pdf</a>, <a href="https://arxiv.org/format/2208.00658">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Physics - Experiment">hep-ex</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.133202">10.1103/PhysRevLett.130.133202 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Constraints on Spin-Spin-Velocity-Dependent Interaction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ji%2C+W">Wei Ji</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Weipeng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Fadeev%2C+P">Pavel Fadeev</a>, <a href="/search/quant-ph?searchtype=author&query=Ficek%2C+F">Filip Ficek</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+J">Jianan Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yong-Chun Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Budker%2C+D">Dmitry Budker</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="2208.00658v2-abstract-short" style="display: inline;"> The existence of exotic spin-dependent forces may shine light on new physics beyond the Standard Model. We utilize two iron shielded SmCo$_5$ electron-spin sources and two optically pumped magnetometers to search for exotic long-range spin-spin-velocity-dependent force. The orientations of spin sources and magnetometers are optimized such that the exotic force is enhanced and common-mode noise is… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.00658v2-abstract-full').style.display = 'inline'; document.getElementById('2208.00658v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.00658v2-abstract-full" style="display: none;"> The existence of exotic spin-dependent forces may shine light on new physics beyond the Standard Model. We utilize two iron shielded SmCo$_5$ electron-spin sources and two optically pumped magnetometers to search for exotic long-range spin-spin-velocity-dependent force. The orientations of spin sources and magnetometers are optimized such that the exotic force is enhanced and common-mode noise is effectively subtracted. We set direct limit on proton-electron interaction in the force range from 1\,cm to 1\,km. Our experiment represents more than ten orders of magnitude improvement than previous works. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.00658v2-abstract-full').style.display = 'none'; document.getElementById('2208.00658v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.04597">arXiv:2207.04597</a> <span> [<a href="https://arxiv.org/pdf/2207.04597">pdf</a>, <a href="https://arxiv.org/format/2207.04597">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.107.012604">10.1103/PhysRevA.107.012604 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimizing nonadiabatic geometric quantum gates against off-resonance error by dynamical correction in a silicon-based spin qubit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+L">Liu-Jun Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Hai Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+Z">Zi-Yu Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Tao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chengxian Zhang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.04597v2-abstract-short" style="display: inline;"> Geometric quantum gates are performed by using the geometric phase, making them particularly robust to the pulse amplitude error due to the intrinsic global property. However, in many systems, such as the silicon-based spin qubits, the off-resonance error is the dominant noise, which can cause dephasing and is always difficult to deal with for a geometric gate. Thus how to deal with the off-resona… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.04597v2-abstract-full').style.display = 'inline'; document.getElementById('2207.04597v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.04597v2-abstract-full" style="display: none;"> Geometric quantum gates are performed by using the geometric phase, making them particularly robust to the pulse amplitude error due to the intrinsic global property. However, in many systems, such as the silicon-based spin qubits, the off-resonance error is the dominant noise, which can cause dephasing and is always difficult to deal with for a geometric gate. Thus how to deal with the off-resonance error is very significant for the application of the geometric gates. A recent work in \emph{Phy. Rev. Appl. 16, 044005 (2021)} reveals that by inserting two $蟺$-pulse dynamically corrected sequences into the evolution paths, the holonomic quantum gate is effective to suppress the pulse amplitude error, however it is still useless for combating the off-resonance error. Inspired by this work, we combine using the techniques of dynamical correction and path design. Surprisingly, we find that by picking up a specific evolution path inserted by only a $蟺$-pulse dynamically corrected sequence, the obtained optimized geometric gate is robust to the off-resonance error, assuming the noise is static. Further, by calculating the filter function considering the realistic $1/f$-type noise in silicon, the related results show that the performance of the optimized geometric gate can also surpass both the conventional geometric gate and the naive dynamical gate constructed without using the geometric phase. Our results indicate dynamical correction is an powerful tool to improve the geometric gate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.04597v2-abstract-full').style.display = 'none'; document.getElementById('2207.04597v2-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 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">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. A 107, 012604 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.00936">arXiv:2201.00936</a> <span> [<a href="https://arxiv.org/pdf/2201.00936">pdf</a>, <a href="https://arxiv.org/format/2201.00936">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.105.012421">10.1103/PhysRevA.105.012421 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental secure quantum key distribution in presence of polarization-dependent loss </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Ye Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+L">Long Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Geng%2C+M">Minming Geng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Junwei Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhenrong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.00936v1-abstract-short" style="display: inline;"> Quantum key distribution (QKD) is theoretically secure using the principle of quantum mechanics; therefore, QKD is a promising solution for the future of secure communication. Although several experimental demonstrations of QKD have been reported, they have not considered the polarization-dependent loss in state preparation in the key-rate estimation. In this study, we experimentally characterized… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.00936v1-abstract-full').style.display = 'inline'; document.getElementById('2201.00936v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.00936v1-abstract-full" style="display: none;"> Quantum key distribution (QKD) is theoretically secure using the principle of quantum mechanics; therefore, QKD is a promising solution for the future of secure communication. Although several experimental demonstrations of QKD have been reported, they have not considered the polarization-dependent loss in state preparation in the key-rate estimation. In this study, we experimentally characterized polarization-dependent loss in realistic state-preparation devices and verified that a considerable PDL exists in fiber- and silicon-based polarization modulators. Hence, the security of such QKD systems is compromised because of the secure key rate overestimation. Furthermore, we report a decoy-state BB84 QKD experiment considering polarization-dependent loss. Finally, we achieved rigorous finite-key security bound over up to 75 km fiber links by applying a recently proposed security proof. This study considers more realistic source flaws than most previous experiments; thus, it is crucial toward a secure QKD with imperfect practical devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.00936v1-abstract-full').style.display = 'none'; document.getElementById('2201.00936v1-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 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.00675">arXiv:2106.00675</a> <span> [<a href="https://arxiv.org/pdf/2106.00675">pdf</a>, <a href="https://arxiv.org/format/2106.00675">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.129.060501">10.1103/PhysRevLett.129.060501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum crosstalk cancellation for fast entangling gates and improved multi-qubit performance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">K. X. Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Magesan%2C+E">E. Magesan</a>, <a href="/search/quant-ph?searchtype=author&query=Lauer%2C+I">I. Lauer</a>, <a href="/search/quant-ph?searchtype=author&query=Srinivasan%2C+S">S. Srinivasan</a>, <a href="/search/quant-ph?searchtype=author&query=Bogorin%2C+D+F">D. F. Bogorin</a>, <a href="/search/quant-ph?searchtype=author&query=Carnevale%2C+S">S. Carnevale</a>, <a href="/search/quant-ph?searchtype=author&query=Keefe%2C+G+A">G. A. Keefe</a>, <a href="/search/quant-ph?searchtype=author&query=Kim%2C+Y">Y. Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Klaus%2C+D">D. Klaus</a>, <a href="/search/quant-ph?searchtype=author&query=Landers%2C+W">W. Landers</a>, <a href="/search/quant-ph?searchtype=author&query=Sundaresan%2C+N">N. Sundaresan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">C. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+E+J">E. J. Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Steffen%2C+M">M. Steffen</a>, <a href="/search/quant-ph?searchtype=author&query=Dial%2C+O+E">O. E. Dial</a>, <a href="/search/quant-ph?searchtype=author&query=McKay%2C+D+C">D. C. McKay</a>, <a href="/search/quant-ph?searchtype=author&query=Kandala%2C+A">A. Kandala</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="2106.00675v1-abstract-short" style="display: inline;"> Quantum computers built with superconducting artificial atoms already stretch the limits of their classical counterparts. While the lowest energy states of these artificial atoms serve as the qubit basis, the higher levels are responsible for both a host of attractive gate schemes as well as generating undesired interactions. In particular, when coupling these atoms to generate entanglement, the h… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.00675v1-abstract-full').style.display = 'inline'; document.getElementById('2106.00675v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.00675v1-abstract-full" style="display: none;"> Quantum computers built with superconducting artificial atoms already stretch the limits of their classical counterparts. While the lowest energy states of these artificial atoms serve as the qubit basis, the higher levels are responsible for both a host of attractive gate schemes as well as generating undesired interactions. In particular, when coupling these atoms to generate entanglement, the higher levels cause shifts in the computational levels that leads to unwanted $ZZ$ quantum crosstalk. Here, we present a novel technique to manipulate the energy levels and mitigate this crosstalk via a simultaneous AC Stark effect on coupled qubits. This breaks a fundamental deadlock between qubit-qubit coupling and crosstalk, leading to a 90ns CNOT with a gate error of (0.19 $\pm$ 0.02) $\%$ and the demonstration of a novel CZ gate with fixed-coupling single-junction transmon qubits. Furthermore, we show a definitive improvement in circuit performance with crosstalk cancellation over seven qubits, demonstrating the scalability of the technique. This work paves the way for superconducting hardware with faster gates and greatly improved multi-qubit circuit fidelities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.00675v1-abstract-full').style.display = 'none'; document.getElementById('2106.00675v1-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 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">8 pages, 5 figures plus Supplementary Information (8 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. 129, 060501 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.07442">arXiv:2104.07442</a> <span> [<a href="https://arxiv.org/pdf/2104.07442">pdf</a>, <a href="https://arxiv.org/format/2104.07442">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/OL.418851">10.1364/OL.418851 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simple Quantum Key Distribution using a Stable Transmitter-Receiver Scheme </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Ma%2C+D">Di Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+X">Xin Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+C">Chunfeng Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+H">Huasheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+H">Huanbin Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.07442v1-abstract-short" style="display: inline;"> Quantum Key Distribution (QKD) is a technology that allows secure key exchange between two distant users. A widespread adoption of QKD requires the development of simple, low-cost, and stable systems. However, implementation of the current QKD requires a complex self-alignment process during the initial stage and an additional hardware to compensate the environmental disturbances. In this study, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07442v1-abstract-full').style.display = 'inline'; document.getElementById('2104.07442v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.07442v1-abstract-full" style="display: none;"> Quantum Key Distribution (QKD) is a technology that allows secure key exchange between two distant users. A widespread adoption of QKD requires the development of simple, low-cost, and stable systems. However, implementation of the current QKD requires a complex self-alignment process during the initial stage and an additional hardware to compensate the environmental disturbances. In this study, we have presented the implementation of a simple QKD with the help of a stable transmitter-receiver scheme, which simplifies the self-alignment and is robust enough to withstand environmental disturbances. In case of the stability test, the implementation system is able to remain stable for 48 hours and exhibits an average quantum bit error rate of less than 1\% without any feedback control. The scheme is also tested over a fiber spool, obtaining a stable and secure finite key rate of 7.32k bits per second over a fiber spool extending up to 75 km. The demonstrated long-term stability and obtained secure key rate prove that our method of implementation is a promising alternative for practical QKD systems, in particular, for Cubesat platform and satellite applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07442v1-abstract-full').style.display = 'none'; document.getElementById('2104.07442v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">13 pages, 3 figures,accepted by Optics Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.07006">arXiv:2104.07006</a> <span> [<a href="https://arxiv.org/pdf/2104.07006">pdf</a>, <a href="https://arxiv.org/format/2104.07006">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optimization and Control">math.OC</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Fast quantum state reconstruction via accelerated non-convex programming </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kim%2C+J+L">Junhyung Lyle Kim</a>, <a href="/search/quant-ph?searchtype=author&query=Kollias%2C+G">George Kollias</a>, <a href="/search/quant-ph?searchtype=author&query=Kalev%2C+A">Amir Kalev</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken X. Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Kyrillidis%2C+A">Anastasios Kyrillidis</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="2104.07006v4-abstract-short" style="display: inline;"> We propose a new quantum state reconstruction method that combines ideas from compressed sensing, non-convex optimization, and acceleration methods. The algorithm, called Momentum-Inspired Factored Gradient Descent (\texttt{MiFGD}), extends the applicability of quantum tomography for larger systems. Despite being a non-convex method, \texttt{MiFGD} converges \emph{provably} close to the true densi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07006v4-abstract-full').style.display = 'inline'; document.getElementById('2104.07006v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.07006v4-abstract-full" style="display: none;"> We propose a new quantum state reconstruction method that combines ideas from compressed sensing, non-convex optimization, and acceleration methods. The algorithm, called Momentum-Inspired Factored Gradient Descent (\texttt{MiFGD}), extends the applicability of quantum tomography for larger systems. Despite being a non-convex method, \texttt{MiFGD} converges \emph{provably} close to the true density matrix at an accelerated linear rate, in the absence of experimental and statistical noise, and under common assumptions. With this manuscript, we present the method, prove its convergence property and provide Frobenius norm bound guarantees with respect to the true density matrix. From a practical point of view, we benchmark the algorithm performance with respect to other existing methods, in both synthetic and real experiments performed on an IBM's quantum processing unit. We find that the proposed algorithm performs orders of magnitude faster than state of the art approaches, with the same or better accuracy. In both synthetic and real experiments, we observed accurate and robust reconstruction, despite experimental and statistical noise in the tomographic data. Finally, we provide a ready-to-use code for state tomography of multi-qubit systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.07006v4-abstract-full').style.display = 'none'; document.getElementById('2104.07006v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">45 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2011.07050">arXiv:2011.07050</a> <span> [<a href="https://arxiv.org/pdf/2011.07050">pdf</a>, <a href="https://arxiv.org/format/2011.07050">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.127.130501">10.1103/PhysRevLett.127.130501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Demonstration of a High-Fidelity CNOT for Fixed-Frequency Transmons with Engineered ZZ Suppression </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Kandala%2C+A">A. Kandala</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">K. X. Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Srinivasan%2C+S">S. Srinivasan</a>, <a href="/search/quant-ph?searchtype=author&query=Magesan%2C+E">E. Magesan</a>, <a href="/search/quant-ph?searchtype=author&query=Carnevale%2C+S">S. Carnevale</a>, <a href="/search/quant-ph?searchtype=author&query=Keefe%2C+G+A">G. A. Keefe</a>, <a href="/search/quant-ph?searchtype=author&query=Klaus%2C+D">D. Klaus</a>, <a href="/search/quant-ph?searchtype=author&query=Dial%2C+O">O. Dial</a>, <a href="/search/quant-ph?searchtype=author&query=McKay%2C+D+C">D. C. McKay</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="2011.07050v1-abstract-short" style="display: inline;"> Improving two-qubit gate performance and suppressing crosstalk are major, but often competing, challenges to achieving scalable quantum computation. In particular, increasing the coupling to realize faster gates has been intrinsically linked to enhanced crosstalk due to unwanted two-qubit terms in the Hamiltonian. Here, we demonstrate a novel coupling architecture for transmon qubits that circumve… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.07050v1-abstract-full').style.display = 'inline'; document.getElementById('2011.07050v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2011.07050v1-abstract-full" style="display: none;"> Improving two-qubit gate performance and suppressing crosstalk are major, but often competing, challenges to achieving scalable quantum computation. In particular, increasing the coupling to realize faster gates has been intrinsically linked to enhanced crosstalk due to unwanted two-qubit terms in the Hamiltonian. Here, we demonstrate a novel coupling architecture for transmon qubits that circumvents the standard relationship between desired and undesired interaction rates. Using two fixed frequency coupling elements to tune the dressed level spacings, we demonstrate an intrinsic suppression of the static $ZZ$, while maintaining large effective coupling rates. Our architecture reveals no observable degradation of qubit coherence ($T_1,T_2 > 100~渭s$) and, over a factor of 6 improvement in the ratio of desired to undesired coupling. Using the cross-resonance interaction we demonstrate a 180~ns single-pulse CNOT gate, and measure a CNOT fidelity of 99.77(2)$\%$ from interleaved randomized benchmarking. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.07050v1-abstract-full').style.display = 'none'; document.getElementById('2011.07050v1-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 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">5 pages, 3 figures plus supplement (4 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. 127, 130501 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.08571">arXiv:2008.08571</a> <span> [<a href="https://arxiv.org/pdf/2008.08571">pdf</a>, <a href="https://arxiv.org/format/2008.08571">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/2058-9565/abe519">10.1088/2058-9565/abe519 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Demonstration of quantum volume 64 on a superconducting quantum computing system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jurcevic%2C+P">Petar Jurcevic</a>, <a href="/search/quant-ph?searchtype=author&query=Javadi-Abhari%2C+A">Ali Javadi-Abhari</a>, <a href="/search/quant-ph?searchtype=author&query=Bishop%2C+L+S">Lev S. Bishop</a>, <a href="/search/quant-ph?searchtype=author&query=Lauer%2C+I">Isaac Lauer</a>, <a href="/search/quant-ph?searchtype=author&query=Bogorin%2C+D+F">Daniela F. Bogorin</a>, <a href="/search/quant-ph?searchtype=author&query=Brink%2C+M">Markus Brink</a>, <a href="/search/quant-ph?searchtype=author&query=Capelluto%2C+L">Lauren Capelluto</a>, <a href="/search/quant-ph?searchtype=author&query=G%C3%BCnl%C3%BCk%2C+O">Oktay G眉nl眉k</a>, <a href="/search/quant-ph?searchtype=author&query=Itoko%2C+T">Toshinari Itoko</a>, <a href="/search/quant-ph?searchtype=author&query=Kanazawa%2C+N">Naoki Kanazawa</a>, <a href="/search/quant-ph?searchtype=author&query=Kandala%2C+A">Abhinav Kandala</a>, <a href="/search/quant-ph?searchtype=author&query=Keefe%2C+G+A">George A. Keefe</a>, <a href="/search/quant-ph?searchtype=author&query=Krsulich%2C+K">Kevin Krsulich</a>, <a href="/search/quant-ph?searchtype=author&query=Landers%2C+W">William Landers</a>, <a href="/search/quant-ph?searchtype=author&query=Lewandowski%2C+E+P">Eric P. Lewandowski</a>, <a href="/search/quant-ph?searchtype=author&query=McClure%2C+D+T">Douglas T. McClure</a>, <a href="/search/quant-ph?searchtype=author&query=Nannicini%2C+G">Giacomo Nannicini</a>, <a href="/search/quant-ph?searchtype=author&query=Narasgond%2C+A">Adinath Narasgond</a>, <a href="/search/quant-ph?searchtype=author&query=Nayfeh%2C+H+M">Hasan M. Nayfeh</a>, <a href="/search/quant-ph?searchtype=author&query=Pritchett%2C+E">Emily Pritchett</a>, <a href="/search/quant-ph?searchtype=author&query=Rothwell%2C+M+B">Mary Beth Rothwell</a>, <a href="/search/quant-ph?searchtype=author&query=Srinivasan%2C+S">Srikanth Srinivasan</a>, <a href="/search/quant-ph?searchtype=author&query=Sundaresan%2C+N">Neereja Sundaresan</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+C">Cindy Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken X. Wei</a> , et al. (6 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="2008.08571v2-abstract-short" style="display: inline;"> We improve the quality of quantum circuits on superconducting quantum computing systems, as measured by the quantum volume, with a combination of dynamical decoupling, compiler optimizations, shorter two-qubit gates, and excited state promoted readout. This result shows that the path to larger quantum volume systems requires the simultaneous increase of coherence, control gate fidelities, measurem… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.08571v2-abstract-full').style.display = 'inline'; document.getElementById('2008.08571v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.08571v2-abstract-full" style="display: none;"> We improve the quality of quantum circuits on superconducting quantum computing systems, as measured by the quantum volume, with a combination of dynamical decoupling, compiler optimizations, shorter two-qubit gates, and excited state promoted readout. This result shows that the path to larger quantum volume systems requires the simultaneous increase of coherence, control gate fidelities, measurement fidelities, and smarter software which takes into account hardware details, thereby demonstrating the need to continue to co-design the software and hardware stack for the foreseeable future. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.08571v2-abstract-full').style.display = 'none'; document.getElementById('2008.08571v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">Fixed typo in author list. Added references [38], [49] and [52]</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Sci. Technol. 6 025020 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.12863">arXiv:2006.12863</a> <span> [<a href="https://arxiv.org/pdf/2006.12863">pdf</a>, <a href="https://arxiv.org/format/2006.12863">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.15.034081">10.1103/PhysRevApplied.15.034081 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental quantum key distribution secure against malicious devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">Victor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+H">Hao Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Min%2C+H">Hao Min</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wei-Yue Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.12863v1-abstract-short" style="display: inline;"> The fabrication of quantum key distribution (QKD) systems typically involves several parties, thus providing Eve with multiple opportunities to meddle with the devices. As a consequence, conventional hardware and/or software hacking attacks pose natural threats to the security of practical QKD. Fortunately, if the number of corrupted devices is limited, the security can be restored by using redund… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.12863v1-abstract-full').style.display = 'inline'; document.getElementById('2006.12863v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.12863v1-abstract-full" style="display: none;"> The fabrication of quantum key distribution (QKD) systems typically involves several parties, thus providing Eve with multiple opportunities to meddle with the devices. As a consequence, conventional hardware and/or software hacking attacks pose natural threats to the security of practical QKD. Fortunately, if the number of corrupted devices is limited, the security can be restored by using redundant apparatuses. Here, we report on the demonstration of a secure QKD setup with optical devices and classical post-processing units possibly controlled by an eavesdropper. We implement a 1.25 GHz chip-based measurement-device-independent QKD system secure against malicious devices on \emph{both} the measurement and the users' sides. The secret key rate reaches 137 bps over a 24 dB channel loss. Our setup, benefiting from high clock rate, miniaturized transmitters and a cost-effective structure, provides a promising solution for widespread applications requiring uncompromising communication security. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.12863v1-abstract-full').style.display = 'none'; document.getElementById('2006.12863v1-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 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">28 pages, 5 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 15, 034081 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.00690">arXiv:1911.00690</a> <span> [<a href="https://arxiv.org/pdf/1911.00690">pdf</a>, <a href="https://arxiv.org/format/1911.00690">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.10.031030">10.1103/PhysRevX.10.031030 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-speed measurement-device-independent quantum key distribution with integrated silicon photonics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+H">Hao Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Min%2C+H">Hao Min</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun 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=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1911.00690v1-abstract-short" style="display: inline;"> Measurement-device-independent quantum key distribution (MDI-QKD) removes all detector side channels and enables secure QKD with an untrusted relay. It is suitable for building a star-type quantum access network, where the complicated and expensive measurement devices are placed in the central untrusted relay and each user requires only a low-cost transmitter, such as an integrated photonic chip.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.00690v1-abstract-full').style.display = 'inline'; document.getElementById('1911.00690v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.00690v1-abstract-full" style="display: none;"> Measurement-device-independent quantum key distribution (MDI-QKD) removes all detector side channels and enables secure QKD with an untrusted relay. It is suitable for building a star-type quantum access network, where the complicated and expensive measurement devices are placed in the central untrusted relay and each user requires only a low-cost transmitter, such as an integrated photonic chip. Here, we experimentally demonstrate a 1.25 GHz silicon photonic chip-based MDI-QKD system using polarization encoding. The photonic chip transmitters integrate the necessary encoding components for a standard QKD source. We implement random modulations of polarization states and decoy intensities, and demonstrate a finite-key secret rate of 31 bps over 36 dB channel loss (or 180 km standard fiber). This key rate is higher than state-of-the-art MDI-QKD experiments. The results show that silicon photonic chip-based MDI-QKD, benefiting from miniaturization, low-cost manufacture and compatibility with CMOS microelectronics, is a promising solution for future quantum secure networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.00690v1-abstract-full').style.display = 'none'; document.getElementById('1911.00690v1-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 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">30 pages, 12 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 10, 031030 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.05720">arXiv:1905.05720</a> <span> [<a href="https://arxiv.org/pdf/1905.05720">pdf</a>, <a href="https://arxiv.org/format/1905.05720">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.101.032343">10.1103/PhysRevA.101.032343 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Verifying Multipartite Entangled GHZ States via Multiple Quantum Coherences </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken X. Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Lauer%2C+I">Isaac Lauer</a>, <a href="/search/quant-ph?searchtype=author&query=Srinivasan%2C+S">Srikanth Srinivasan</a>, <a href="/search/quant-ph?searchtype=author&query=Sundaresan%2C+N">Neereja Sundaresan</a>, <a href="/search/quant-ph?searchtype=author&query=McClure%2C+D+T">Douglas T. McClure</a>, <a href="/search/quant-ph?searchtype=author&query=Toyli%2C+D">David Toyli</a>, <a href="/search/quant-ph?searchtype=author&query=McKay%2C+D+C">David C. McKay</a>, <a href="/search/quant-ph?searchtype=author&query=Gambetta%2C+J+M">Jay M. Gambetta</a>, <a href="/search/quant-ph?searchtype=author&query=Sheldon%2C+S">Sarah Sheldon</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="1905.05720v1-abstract-short" style="display: inline;"> The ability to generate and verify multipartite entanglement is an important benchmark for near-term quantum devices devices. We develop a scalable entanglement metric based on multiple quantum coherences, and demonstrate experimentally on a 20-qubit superconducting device - the IBM Q System One. We report a state fidelity of 0.5165$\pm$0.0036 for an 18-qubit GHZ state, indicating multipartite ent… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.05720v1-abstract-full').style.display = 'inline'; document.getElementById('1905.05720v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.05720v1-abstract-full" style="display: none;"> The ability to generate and verify multipartite entanglement is an important benchmark for near-term quantum devices devices. We develop a scalable entanglement metric based on multiple quantum coherences, and demonstrate experimentally on a 20-qubit superconducting device - the IBM Q System One. We report a state fidelity of 0.5165$\pm$0.0036 for an 18-qubit GHZ state, indicating multipartite entanglement across all 18 qubits. Our entanglement metric is robust to noise and only requires measuring the population in the ground state; it can be readily applied to other quantum devices to verify multipartite entanglement. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.05720v1-abstract-full').style.display = 'none'; document.getElementById('1905.05720v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 May, 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">7+4 pages, comments 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 101, 032343 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1903.07862">arXiv:1903.07862</a> <span> [<a href="https://arxiv.org/pdf/1903.07862">pdf</a>, <a href="https://arxiv.org/format/1903.07862">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.123.100503">10.1103/PhysRevLett.123.100503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Remote blind state preparation with weak coherent pulses in the field </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Y">Yang-Fan Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+L">Liang Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+K">Ke Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+Q">Qi-Chao Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yu-Zhe Zhang</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=Lo%2C+H">Hoi-Kwong Lo</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="1903.07862v2-abstract-short" style="display: inline;"> Quantum computing has seen tremendous progress in the past years. Due to the implementation complexity and cost, the future path of quantum computation is strongly believed to delegate computational tasks to powerful quantum servers on cloud. Universal blind quantum computing (UBQC) provides the protocol for the secure delegation of arbitrary quantum computations, and it has received significant a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.07862v2-abstract-full').style.display = 'inline'; document.getElementById('1903.07862v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1903.07862v2-abstract-full" style="display: none;"> Quantum computing has seen tremendous progress in the past years. Due to the implementation complexity and cost, the future path of quantum computation is strongly believed to delegate computational tasks to powerful quantum servers on cloud. Universal blind quantum computing (UBQC) provides the protocol for the secure delegation of arbitrary quantum computations, and it has received significant attention. However, a great challenge in UBQC is how to transmit quantum state over long distance securely and reliably. Here, we solve this challenge by proposing and demonstrating a resource-efficient remote blind qubit preparation (RBQP) protocol with weak coherent pulses for the client to produce, using a compact and low-cost laser. We demonstrate the protocol in field, experimentally verifying the protocol over 100-km fiber. Our experiment uses a quantum teleportation setup in telecom wavelength and generates $1000$ secure qubits with an average fidelity of $(86.9\pm1.5)\%$, which exceeds the quantum no-cloning fidelity of equatorial qubit states. The results prove the feasibility of UBQC over long distances, and thus serving as a key milestone towards secure cloud quantum computing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1903.07862v2-abstract-full').style.display = 'none'; document.getElementById('1903.07862v2-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 19 March, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">11 pages, 9 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, 100503 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.06628">arXiv:1902.06628</a> <span> [<a href="https://arxiv.org/pdf/1902.06628">pdf</a>, <a href="https://arxiv.org/format/1902.06628">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> </div> <div 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.124.030601">10.1103/PhysRevLett.124.030601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Emergent perturbation independent decay of the Loschmidt echo in a many-spin system studied through scaled dipolar dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=S%C3%A1nchez%2C+C+M">Claudia M. S谩nchez</a>, <a href="/search/quant-ph?searchtype=author&query=Chattah%2C+A+K">Ana Karina Chattah</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken Xuan Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Buljubasich%2C+L">Lisandro Buljubasich</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</a>, <a href="/search/quant-ph?searchtype=author&query=Pastawski%2C+H+M">Horacio M. Pastawski</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="1902.06628v1-abstract-short" style="display: inline;"> Evaluating the role of perturbations versus the intrinsic coherent dynamics in driving to equilibrium is of fundamental interest to understand quantum many-body thermalization, in the quest to build ever complex quantum devices. Here we introduce a protocol that scales down the coupling strength in a quantum simulator based on a solid-state nuclear spin system, leading to a longer decay time T2, w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.06628v1-abstract-full').style.display = 'inline'; document.getElementById('1902.06628v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.06628v1-abstract-full" style="display: none;"> Evaluating the role of perturbations versus the intrinsic coherent dynamics in driving to equilibrium is of fundamental interest to understand quantum many-body thermalization, in the quest to build ever complex quantum devices. Here we introduce a protocol that scales down the coupling strength in a quantum simulator based on a solid-state nuclear spin system, leading to a longer decay time T2, while keeping perturbations associated to control error constant. We can monitor quantum information scrambling by measuring two powerful metrics, out-of-time-ordered correlators (OTOCs) and Loschmidt Echoes (LEs). While OTOCs reveal quantum information scrambling involving hundreds of spins, the LE decay quantifies, via the time scale T3, how well the scrambled information can be recovered through time reversal. We find that when the interactions dominate the perturbation, the LE decay rate only depends on the interactions themselves, T3 ~ T2, and not on the perturbation. Then, in an unbounded many-spin system, decoherence can achieve a perturbation-independent regime, with a rate only related to the local second moment of the Hamiltonian. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.06628v1-abstract-full').style.display = 'none'; document.getElementById('1902.06628v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 February, 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">Journal ref:</span> Phys. Rev. Lett. 124, 030601 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.00034">arXiv:1901.00034</a> <span> [<a href="https://arxiv.org/pdf/1901.00034">pdf</a>, <a href="https://arxiv.org/format/1901.00034">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.100.214203">10.1103/PhysRevB.100.214203 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Comparing many-body localization lengths via non-perturbative construction of local integrals of motion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Peng%2C+P">Pai Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zeyang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+H">Haoxiong Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken Xuan Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1901.00034v1-abstract-short" style="display: inline;"> Many-body localization (MBL), characterized by the absence of thermalization and the violation of conventional thermodynamics, has elicited much interest both as a fundamental physical phenomenon and for practical applications in quantum information. A phenomenological model, which describes the system using a complete set of local integrals of motion (LIOMs), provides a powerful tool to understan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.00034v1-abstract-full').style.display = 'inline'; document.getElementById('1901.00034v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.00034v1-abstract-full" style="display: none;"> Many-body localization (MBL), characterized by the absence of thermalization and the violation of conventional thermodynamics, has elicited much interest both as a fundamental physical phenomenon and for practical applications in quantum information. A phenomenological model, which describes the system using a complete set of local integrals of motion (LIOMs), provides a powerful tool to understand MBL, but can be usually only computed approximately. Here we explicitly compute a complete set of LIOMs with a non-perturbative approach, by maximizing the overlap between LIOMs and physical spin operators in real space. The set of LIOMs satisfies the desired exponential decay of weight of LIOMs in real-space. This LIOM construction enables a direct mapping from the real space Hamiltonian to the phenomenological model and thus enables studying the localized Hamiltonian and the system dynamics. We can thus study and compare the localization lengths extracted from the LIOM weights, their interactions, and dephasing dynamics, revealing interesting aspects of many-body localization. Our scheme is immune to accidental resonances and can be applied even at phase transition point, providing a novel tool to study the microscopic features of the phenomenological model of MBL. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.00034v1-abstract-full').style.display = 'none'; document.getElementById('1901.00034v1-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 December, 2018; <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">Comments:</span> <span class="has-text-grey-dark mathjax">8+3 pages, 8+6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 100, 214203 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.04776">arXiv:1812.04776</a> <span> [<a href="https://arxiv.org/pdf/1812.04776">pdf</a>, <a href="https://arxiv.org/format/1812.04776">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Statistical Mechanics">cond-mat.stat-mech</span> </div> <div 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.123.090605">10.1103/PhysRevLett.123.090605 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Emergent prethermalization signatures in out-of-time ordered correlations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken Xuan Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+P">Pai Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Shtanko%2C+O">Oles Shtanko</a>, <a href="/search/quant-ph?searchtype=author&query=Marvian%2C+I">Iman Marvian</a>, <a href="/search/quant-ph?searchtype=author&query=Lloyd%2C+S">Seth Lloyd</a>, <a href="/search/quant-ph?searchtype=author&query=Ramanathan%2C+C">Chandrasekhar Ramanathan</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1812.04776v1-abstract-short" style="display: inline;"> How a many-body quantum system thermalizes --or fails to do so-- under its own interaction is a fundamental yet elusive concept. Here we demonstrate nuclear magnetic resonance observation of the emergence of prethermalization by measuring out-of-time ordered correlations. We exploit Hamiltonian engineering techniques to tune the strength of spin-spin interactions and of a transverse magnetic field… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.04776v1-abstract-full').style.display = 'inline'; document.getElementById('1812.04776v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.04776v1-abstract-full" style="display: none;"> How a many-body quantum system thermalizes --or fails to do so-- under its own interaction is a fundamental yet elusive concept. Here we demonstrate nuclear magnetic resonance observation of the emergence of prethermalization by measuring out-of-time ordered correlations. We exploit Hamiltonian engineering techniques to tune the strength of spin-spin interactions and of a transverse magnetic field in a spin chain system, as well as to invert the Hamiltonian sign to reveal out-of-time ordered correlations. At large fields, we observe an emergent conserved quantity due to prethermalization, which can be revealed by an early saturation of correlations. Our experiment not only demonstrates a new protocol to measure out-of-time ordered correlations, but also provides new insights in the study of quantum thermodynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.04776v1-abstract-full').style.display = 'none'; document.getElementById('1812.04776v1-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 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">6+12 pages, 3+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, 090605 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.10238">arXiv:1810.10238</a> <span> [<a href="https://arxiv.org/pdf/1810.10238">pdf</a>, <a href="https://arxiv.org/format/1810.10238">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.122.120504">10.1103/PhysRevLett.122.120504 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Quantum Switching for Exponentially Superior Quantum Communication Complexity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Tischler%2C+N">Nora Tischler</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+S">Si-Ran Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</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=Liu%2C+Y">Yang Liu</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=Chen%2C+Y">Yu-Ao Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Sanders%2C+B+C">Barry C. Sanders</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pryde%2C+G+J">Geoff J. Pryde</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.10238v2-abstract-short" style="display: inline;"> Finding exponential separation between quantum and classical information tasks is like striking gold in quantum information research. Such an advantage is believed to hold for quantum computing but is proven for quantum communication complexity. Recently, a novel quantum resource called the quantum switch---which creates a coherent superposition of the causal order of events, known as quantum caus… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.10238v2-abstract-full').style.display = 'inline'; document.getElementById('1810.10238v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.10238v2-abstract-full" style="display: none;"> Finding exponential separation between quantum and classical information tasks is like striking gold in quantum information research. Such an advantage is believed to hold for quantum computing but is proven for quantum communication complexity. Recently, a novel quantum resource called the quantum switch---which creates a coherent superposition of the causal order of events, known as quantum causality---has been harnessed theoretically in a new protocol providing provable exponential separation. We experimentally demonstrate such an advantage by realizing a superposition of communication directions for a two-party distributed computation. Our photonic demonstration employs $d$-dimensional quantum systems, qudits, up to $d=2^{13}$ dimensions and demonstrates a communication complexity advantage, requiring less than $(0.696 \pm 0.006)$ times the communication of any causally ordered protocol. These results elucidate the crucial role of the coherence of communication direction in achieving the exponential separation for the one-way processing task, and open a new path for experimentally exploring the fundamentals and applications of advanced features of indefinite causal structures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.10238v2-abstract-full').style.display = 'none'; document.getElementById('1810.10238v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 March, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">Accepted by Phys. Rev. Lett</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 122, 120504 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1808.08584">arXiv:1808.08584</a> <span> [<a href="https://arxiv.org/pdf/1808.08584">pdf</a>, <a href="https://arxiv.org/format/1808.08584">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.122.160501">10.1103/PhysRevLett.122.160501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental demonstration of high-rate measurement-device-independent quantum key distribution over asymmetric channels </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hui Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wenyuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+X">Xiao-Tian Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Li Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+N">Nai-Le Liu</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+S">Si-Jie Zhang</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=Lo%2C+H">Hoi-Kwong Lo</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1808.08584v2-abstract-short" style="display: inline;"> Measurement-device-independent quantum key distribution (MDI-QKD) can eliminate all detector side channels and it is practical with current technology. Previous implementations of MDI-QKD all use two symmetric channels with similar losses. However, the secret key rate is severely limited when different channels have different losses. Here we report the results of the first high-rate MDI-QKD experi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.08584v2-abstract-full').style.display = 'inline'; document.getElementById('1808.08584v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1808.08584v2-abstract-full" style="display: none;"> Measurement-device-independent quantum key distribution (MDI-QKD) can eliminate all detector side channels and it is practical with current technology. Previous implementations of MDI-QKD all use two symmetric channels with similar losses. However, the secret key rate is severely limited when different channels have different losses. Here we report the results of the first high-rate MDI-QKD experiment over $asymmetric$ channels. By using the recent 7-intensity optimization approach, we demonstrate $>$10x higher key rate than previous best-known protocols for MDI-QKD in the situation of large channel asymmetry, and extend the secure transmission distance by more than 20-50 km in standard telecom fiber. The results have moved MDI-QKD towards widespread applications in practical network settings, where the channel losses are asymmetric and user nodes could be dynamically added or deleted. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.08584v2-abstract-full').style.display = 'none'; document.getElementById('1808.08584v2-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 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">20 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. 122, 160501 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1701.00059">arXiv:1701.00059</a> <span>  </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"> Secret sharing without monitoring signal disturbance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiuqing Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+H">Haiqiang Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+C">Changhua Zhu</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="1701.00059v2-abstract-short" style="display: inline;"> Secret sharing, in which a dealer wants to split a secret in such a way that any unauthorized subset of parties is unable to reconstruct it, plays a key role in cryptography. The security of quantum protocols for the task is guaranteed by the fact that Eve's any strategies to obtain secret information from encoded quantum states should cause a disturbance in the signal. Here, we propose a quantum… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.00059v2-abstract-full').style.display = 'inline'; document.getElementById('1701.00059v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1701.00059v2-abstract-full" style="display: none;"> Secret sharing, in which a dealer wants to split a secret in such a way that any unauthorized subset of parties is unable to reconstruct it, plays a key role in cryptography. The security of quantum protocols for the task is guaranteed by the fact that Eve's any strategies to obtain secret information from encoded quantum states should cause a disturbance in the signal. Here, we propose a quantum secret sharing (classical information) scheme for $N$ parties based on totally different principle in which monitoring signal disturbance is no longer need. In this scheme, the secret is divided among several partners by sequential transmissions of a $L$-dimensional qudit state, which can be practically implemented using a conventional laser and some standard off-the-shelf components. Our scheme paves a novel and practical way for quantum secret sharing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1701.00059v2-abstract-full').style.display = 'none'; document.getElementById('1701.00059v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">The paper has been withdrawn by the author due to potential loophole in the proposed scheme and is currently under revision</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.05249">arXiv:1612.05249</a> <span> [<a href="https://arxiv.org/pdf/1612.05249">pdf</a>, <a href="https://arxiv.org/format/1612.05249">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="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.120.070501">10.1103/PhysRevLett.120.070501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring Localization in Nuclear Spin Chains </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K+X">Ken Xuan Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Ramanathan%2C+C">Chandrasekhar Ramanathan</a>, <a href="/search/quant-ph?searchtype=author&query=Cappellaro%2C+P">Paola Cappellaro</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1612.05249v1-abstract-short" style="display: inline;"> Characterizing out-of-equilibrium many-body dynamics is a complex but crucial task for quantum applications and the understanding of fundamental phenomena. A central question is the role of localization in quenching quantum thermalization, and whether localization survives in the presence of interactions. The localized phase of interacting systems (many-body localization, MBL) exhibits a long-time… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.05249v1-abstract-full').style.display = 'inline'; document.getElementById('1612.05249v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.05249v1-abstract-full" style="display: none;"> Characterizing out-of-equilibrium many-body dynamics is a complex but crucial task for quantum applications and the understanding of fundamental phenomena. A central question is the role of localization in quenching quantum thermalization, and whether localization survives in the presence of interactions. The localized phase of interacting systems (many-body localization, MBL) exhibits a long-time logarithmic growth in entanglement entropy that distinguishes it from the noninteracting Anderson localization (AL), but entanglement is difficult to measure experimentally. Here, we present a novel correlation metric, capable of distinguishing MBL from AL in high-temperature spin systems. We demonstrate the use of this metric to detect localization in a natural solidstate spin system using nuclear magnetic resonance (NMR). We engineer the natural Hamiltonian to controllably introduce disorder and interactions and observe the emergence of localization. In particular, while our correlation metric saturates for AL, it keeps increasing logarithmically for MBL, a behavior reminiscent of entanglement entropy, as we confirm by simulations. Our results show that our NMR techniques, akin to measuring out-of-time correlations, are well suited for studying localization in spin systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.05249v1-abstract-full').style.display = 'none'; document.getElementById('1612.05249v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 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">6 + 11 pages, 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. Lett. 120, 070501 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1608.00114">arXiv:1608.00114</a> <span>  </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-device-independent quantum secret sharing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiuqing Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+H">Haiqiang Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shihai Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hongwei Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zuohan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+Z">Zhenqiang Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+Y">Yungang Du</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+L">Lingan Wu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1608.00114v3-abstract-short" style="display: inline;"> Measurement-device-independent entanglement witness (MDI-EW) will always give an affirmative certification for witnessing entanglement with untrusted measurement apparatuses. Using the MDI-EW method, we propose a measurement-device-independent quantum secret sharing (MDI-QSS) protocol that Charlie can securely distribute a key between the two agents Alice and Bob. A tight bound for collective atta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.00114v3-abstract-full').style.display = 'inline'; document.getElementById('1608.00114v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1608.00114v3-abstract-full" style="display: none;"> Measurement-device-independent entanglement witness (MDI-EW) will always give an affirmative certification for witnessing entanglement with untrusted measurement apparatuses. Using the MDI-EW method, we propose a measurement-device-independent quantum secret sharing (MDI-QSS) protocol that Charlie can securely distribute a key between the two agents Alice and Bob. A tight bound for collective attacks can provide good bounds on the long-distance MDI-QSS with source flaws. Then we show through numerical simulations that using single-photon source a secure QSS over 136 km can be achieved. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1608.00114v3-abstract-full').style.display = 'none'; document.getElementById('1608.00114v3-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 February, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 July, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">This paper has been modified to another work</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1508.03562">arXiv:1508.03562</a> <span> [<a href="https://arxiv.org/pdf/1508.03562">pdf</a>, <a href="https://arxiv.org/format/1508.03562">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.93.042308">10.1103/PhysRevA.93.042308 <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 Key Distribution with Imperfect Sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Z">Zhiyuan Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Bedroya%2C+O">Olinka Bedroya</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+L">Li Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1508.03562v2-abstract-short" style="display: inline;"> Measurement-device-independent quantum key distribution (MDI-QKD), which is immune to all detector side-channel attacks, is the most promising solution to the security issues in practical quantum key distribution systems. Though several experimental demonstrations of MDI QKD have been reported, they all make one crucial but not yet verified assumption, that is there are no flaws in state preparati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.03562v2-abstract-full').style.display = 'inline'; document.getElementById('1508.03562v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1508.03562v2-abstract-full" style="display: none;"> Measurement-device-independent quantum key distribution (MDI-QKD), which is immune to all detector side-channel attacks, is the most promising solution to the security issues in practical quantum key distribution systems. Though several experimental demonstrations of MDI QKD have been reported, they all make one crucial but not yet verified assumption, that is there are no flaws in state preparation. Such an assumption is unrealistic and security loopholes remain in the source. Here we present, to our knowledge, the first MDI-QKD experiment with state preparation flaws taken into consideration. By applying a novel security proof by Tamaki \textit{et al} (Phys. Rev. A 90, 052314 (2014)), we distribute secure keys over fiber links up to 40 km with imperfect sources, which would not have been possible under previous security proofs. By closing loopholes in both the sources and the detectors, our work shows the feasibility of secure QKD with practical imperfect devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.03562v2-abstract-full').style.display = 'none'; document.getElementById('1508.03562v2-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 January, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 August, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">15 pages, 8 figures, including supplemental material</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1503.05499">arXiv:1503.05499</a> <span> [<a href="https://arxiv.org/pdf/1503.05499">pdf</a>, <a href="https://arxiv.org/format/1503.05499">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/ncomms9735">10.1038/ncomms9735 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Quantum Fingerprinting </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</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=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wenyuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Palacios-Avila%2C+P">Pablo Palacios-Avila</a>, <a href="/search/quant-ph?searchtype=author&query=Feng%2C+C">Chen Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Sajeed%2C+S">Shihan Sajeed</a>, <a href="/search/quant-ph?searchtype=author&query=L%7F%C3%BCtkenhaus%2C+N">Norbert L眉tkenhaus</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1503.05499v1-abstract-short" style="display: inline;"> Quantum communication holds the promise of creating disruptive technologies that will play an essential role in future communication networks. For example, the study of quantum communication complexity has shown that quantum communication allows exponential reductions in the information that must be transmitted to solve distributed computational tasks. Recently, protocols that realize this advanta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.05499v1-abstract-full').style.display = 'inline'; document.getElementById('1503.05499v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1503.05499v1-abstract-full" style="display: none;"> Quantum communication holds the promise of creating disruptive technologies that will play an essential role in future communication networks. For example, the study of quantum communication complexity has shown that quantum communication allows exponential reductions in the information that must be transmitted to solve distributed computational tasks. Recently, protocols that realize this advantage using optical implementations have been proposed. Here we report a proof of concept experimental demonstration of a quantum fingerprinting system that is capable of transmitting less information than the best known classical protocol. Our implementation is based on a modified version of a commercial quantum key distribution system using off-the-shelf optical components over telecom wavelengths, and is practical for messages as large as 100 Mbits, even in the presence of experimental imperfections. Our results provide a first step in the development of experimental quantum communication complexity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.05499v1-abstract-full').style.display = 'none'; document.getElementById('1503.05499v1-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 March, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">11 pages, 6 Figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 6, 8735 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1408.3667">arXiv:1408.3667</a> <span> [<a href="https://arxiv.org/pdf/1408.3667">pdf</a>, <a href="https://arxiv.org/ps/1408.3667">ps</a>, <a href="https://arxiv.org/format/1408.3667">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.92.032305">10.1103/PhysRevA.92.032305 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental quantum key distribution with source flaws </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Sajeed%2C+S">Shihan Sajeed</a>, <a href="/search/quant-ph?searchtype=author&query=Kaiser%2C+S">Sarah Kaiser</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shihai Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Z">Zhiyuan Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+L">Li Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Makarov%2C+V">Vadim Makarov</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1408.3667v2-abstract-short" style="display: inline;"> Decoy-state quantum key distribution (QKD) is a standard technique in current quantum cryptographic implementations. Unfortunately, existing experiments have two important drawbacks: the state preparation is assumed to be perfect without errors and the employed security proofs do not fully consider the finite-key effects for general attacks. These two drawbacks mean that existing experiments are n… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.3667v2-abstract-full').style.display = 'inline'; document.getElementById('1408.3667v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1408.3667v2-abstract-full" style="display: none;"> Decoy-state quantum key distribution (QKD) is a standard technique in current quantum cryptographic implementations. Unfortunately, existing experiments have two important drawbacks: the state preparation is assumed to be perfect without errors and the employed security proofs do not fully consider the finite-key effects for general attacks. These two drawbacks mean that existing experiments are not guaranteed to be secure in practice. Here, we perform an experiment that for the first time shows secure QKD with imperfect state preparations over long distances and achieves rigorous finite-key security bounds for decoy-state QKD against coherent attacks in the universally composable framework. We quantify the source flaws experimentally and demonstrate a QKD implementation that is tolerant to channel loss despite the source flaws. Our implementation considers more real-world problems than most previous experiments and our theory can be applied to general QKD systems. These features constitute a step towards secure QKD with imperfect devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.3667v2-abstract-full').style.display = 'none'; document.getElementById('1408.3667v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 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">12 pages, 4 figures, updated experiment and theory</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 92, 032305 (2015) </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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