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class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2411.13943">arXiv:2411.13943</a> <span> [<a href="https://arxiv.org/pdf/2411.13943">pdf</a>, <a href="https://arxiv.org/format/2411.13943">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Independent Optical Frequency Combs Powered 546 km Field Test of Twin-Field Quantum Key Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+L">Lai Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+J">Jinping Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Ge%2C+C">Chengfang Ge</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yuanbin Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+Z">Zhiliang Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+H">Hao Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+D">Di Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=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="2411.13943v1-abstract-short" style="display: inline;"> Owing to its repeater-like rate-loss scaling, twin-field quantum key distribution (TF-QKD) has repeatedly exhibited in laboratory its superiority for secure communication over record fiber lengths. Field trials pose a new set of challenges however, which must be addressed before the technology's roll-out into real-world. Here, we verify in field the viability of using independent optical frequency… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.13943v1-abstract-full').style.display = 'inline'; document.getElementById('2411.13943v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.13943v1-abstract-full" style="display: none;"> Owing to its repeater-like rate-loss scaling, twin-field quantum key distribution (TF-QKD) has repeatedly exhibited in laboratory its superiority for secure communication over record fiber lengths. Field trials pose a new set of challenges however, which must be addressed before the technology's roll-out into real-world. Here, we verify in field the viability of using independent optical frequency combs -- installed at sites separated by a straight-line distance of 300~km -- to achieve a versatile TF-QKD setup that has no need for optical frequency dissemination and thus enables an open and network-friendly fiber configuration. Over 546 and 603 km symmetric links, we record a finite-size secure key rate (SKR) of 0.53~bit/s and an asymptotic SKR of 0.12 bit/s, respectively. Of practical importance, the setup is demonstrated to support 44~km fiber asymmetry in the 452 km link. Our work marks an important step towards incorporation of long-haul fiber links into large quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.13943v1-abstract-full').style.display = 'none'; document.getElementById('2411.13943v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">To appear in Physical Review Applied</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.18516">arXiv:2410.18516</a> <span> [<a href="https://arxiv.org/pdf/2410.18516">pdf</a>, <a href="https://arxiv.org/format/2410.18516">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"> Integrated spectrally multiplexed light-matter interface at telecom band </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xueying Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+B">Bin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+S">Shihai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+J">Jinyu Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+T">Tao Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guangwei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Haizhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+B">Boyu Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yunru Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Feng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guangcan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.18516v1-abstract-short" style="display: inline;"> Light-matter interface is an important building block for long-distance quantum networks. Towards a scalable quantum network with high-rate quantum information processing, it requires to develop integrated light-matter interfaces with broadband and multiplexing capacities. Here we demonstrate a light-matter interface at telecom band in an integrated system. A five-spectral-channel atomic-frequency… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.18516v1-abstract-full').style.display = 'inline'; document.getElementById('2410.18516v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.18516v1-abstract-full" style="display: none;"> Light-matter interface is an important building block for long-distance quantum networks. Towards a scalable quantum network with high-rate quantum information processing, it requires to develop integrated light-matter interfaces with broadband and multiplexing capacities. Here we demonstrate a light-matter interface at telecom band in an integrated system. A five-spectral-channel atomic-frequency-comb photonic memory is prepared on a laser-written Er3+:LiNbO3 chip. The bandwidth of each channel is 4 GHz with a channel spacing of 15 GHz. The signal photons from time-bin entangled photon pairs at telecom band are sent into the on-chip memory and recalled after a storage time of 152 ns. The entanglement-preserving nature of our integrated quantum interface is assessed by an input/output fidelity of >92% for all the five spectral channels. Our light-matter interfaces constitute a notable step forward toward a high-rate quantum network involving integrated device. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.18516v1-abstract-full').style.display = 'none'; document.getElementById('2410.18516v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.16174">arXiv:2410.16174</a> <span> [<a href="https://arxiv.org/pdf/2410.16174">pdf</a>, <a href="https://arxiv.org/format/2410.16174">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Observation of anomalous information scrambling in a Rydberg atom array </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liang%2C+X">Xinhui Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Yue%2C+Z">Zongpei Yue</a>, <a href="/search/quant-ph?searchtype=author&query=Chao%2C+Y">Yu-Xin Chao</a>, <a href="/search/quant-ph?searchtype=author&query=Hua%2C+Z">Zhen-Xing Hua</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Y">Yige Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Tey%2C+M+K">Meng Khoon Tey</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.16174v1-abstract-short" style="display: inline;"> Quantum information scrambling, which describes the propagation and effective loss of local information, is crucial for understanding the dynamics of quantum many-body systems. In general, a typical interacting system would thermalize under time evolution, leading to the emergence of ergodicity and linear lightcones of information scrambling. Whereas, for a many-body localized system, strong disor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16174v1-abstract-full').style.display = 'inline'; document.getElementById('2410.16174v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.16174v1-abstract-full" style="display: none;"> Quantum information scrambling, which describes the propagation and effective loss of local information, is crucial for understanding the dynamics of quantum many-body systems. In general, a typical interacting system would thermalize under time evolution, leading to the emergence of ergodicity and linear lightcones of information scrambling. Whereas, for a many-body localized system, strong disorders give rise to an extensive number of conserved quantities that prevent the system from thermalization, resulting in full ergodicity breaking and a logarithmic lightcone for information spreading. Here, we report the experimental observation of anomalous information scrambling in an atomic tweezer array. Working in the Rydberg blockade regime, where van der Waals interaction dominates, we observe a suppressed linear lightcone of information spreading characterized by out-of-time-order correlators for the initial N茅el state, accompanied by persistent oscillations within the lightcone. Such an anomalous dynamics differs from both generic thermal and many-body localized scenarios. It originates from weak ergodicity breaking and is the characteristic feature for quantum many-body scars. The high-quality single-atom manipulations and coherent constraint dynamics, augmented by the effective protocol for time-reversed evolution we demonstrate, establish a versatile hybrid analog-digital simulation approach to explore diverse exotic non-equilibrium dynamics with atomic tweezer arrays. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.16174v1-abstract-full').style.display = 'none'; document.getElementById('2410.16174v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.13063">arXiv:2408.13063</a> <span> [<a href="https://arxiv.org/pdf/2408.13063">pdf</a>, <a href="https://arxiv.org/format/2408.13063">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 practical quantum tokens with transaction time advantage </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=Kent%2C+A">Adrian Kent</a>, <a href="/search/quant-ph?searchtype=author&query=Pital%C3%BAa-Garc%C3%ADa%2C+D">Dami谩n Pital煤a-Garc铆a</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+X">Xiaochen Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+X">Xiaohan Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Cowperthwaite%2C+G">George Cowperthwaite</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+Q">Qibin Zheng</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=Liu%2C+Y">Yang Liu</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="2408.13063v2-abstract-short" style="display: inline;"> Quantum money is the first invention in quantum information science, promising advantages over classical money by simultaneously achieving unforgeability, user privacy, and instant validation. However, standard quantum money relies on quantum memories and long-distance quantum communication, which are technologically extremely challenging. Quantum "S-money" tokens eliminate these technological req… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13063v2-abstract-full').style.display = 'inline'; document.getElementById('2408.13063v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.13063v2-abstract-full" style="display: none;"> Quantum money is the first invention in quantum information science, promising advantages over classical money by simultaneously achieving unforgeability, user privacy, and instant validation. However, standard quantum money relies on quantum memories and long-distance quantum communication, which are technologically extremely challenging. Quantum "S-money" tokens eliminate these technological requirements while preserving unforgeability, user privacy, and instant validation. Here, we report the first full experimental demonstration of quantum S-tokens, proven secure despite errors, losses and experimental imperfections. The heralded single-photon source with a high system efficiency of 88.24% protects against arbitrary multi-photon attacks arising from losses in the quantum token generation. Following short-range quantum communication, the token is stored, transacted, and verified using classical bits. We demonstrate a transaction time advantage over intra-city 2.77 km and inter-city 60.54 km optical fibre networks, compared with optimal classical cross-checking schemes. Our implementation demonstrates the practicality of quantum S-tokens for applications requiring high security, privacy and minimal transaction times, like financial trading and network control. It is also the first demonstration of a quantitative quantum time advantage in relativistic cryptography, showing the enhanced cryptographic power of simultaneously considering quantum and relativistic physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.13063v2-abstract-full').style.display = 'none'; document.getElementById('2408.13063v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">74 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/2408.10489">arXiv:2408.10489</a> <span> [<a href="https://arxiv.org/pdf/2408.10489">pdf</a>, <a href="https://arxiv.org/format/2408.10489">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"> Interplay of Quantum Resources in Nonlocality Tests </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Dong%2C+H">Hai-Hao Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+Y">Yuwei Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Cheng%2C+S">Su-Yi Cheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xingjian Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Cheng-Long Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Ying-Zhao Li</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=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.10489v1-abstract-short" style="display: inline;"> Nonlocality, evidenced by the violation of Bell inequalities, not only signifies entanglement but also highlights measurement incompatibility in quantum systems. Utilizing the generalized Clauser-Horne-Shimony-Holt (CHSH) Bell inequality, our high-efficiency optical setup achieves a loophole-free violation of $2.0132$. This result provides a device-independent lower bound on entanglement, quantifi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10489v1-abstract-full').style.display = 'inline'; document.getElementById('2408.10489v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.10489v1-abstract-full" style="display: none;"> Nonlocality, evidenced by the violation of Bell inequalities, not only signifies entanglement but also highlights measurement incompatibility in quantum systems. Utilizing the generalized Clauser-Horne-Shimony-Holt (CHSH) Bell inequality, our high-efficiency optical setup achieves a loophole-free violation of $2.0132$. This result provides a device-independent lower bound on entanglement, quantified as the entanglement of formation at $0.0159$. Moreover, by tuning the parameters of the generalized Bell inequality, we enhance the estimation of measurement incompatibility, which is quantified by an effective overlap of $4.3883 \times 10^{-5}$. To explore the intricate interplay among nonlocality, entanglement, and measurement incompatibility, we generate mixed states, allowing for flexible modulation of entanglement via fast switching among the four Bell states using Pockels cells, achieving a fidelity above $99.10\%$. Intriguingly, our results reveal a counterintuitive relationship where increasing incompatibility initially boosts nonlocality but eventually leads to its reduction. Typically, maximal nonlocality does not coincide with maximal incompatibility. This experimental study sheds light on the optimal management of quantum resources for Bell-inequality-based quantum information processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.10489v1-abstract-full').style.display = 'none'; document.getElementById('2408.10489v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2408.04361">arXiv:2408.04361</a> <span> [<a href="https://arxiv.org/pdf/2408.04361">pdf</a>, <a href="https://arxiv.org/format/2408.04361">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"> Ultrabright-entanglement-based quantum key distribution over a 404-km-long optical fiber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhuang%2C+S">Shi-Chang Zhuang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+B">Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+M">Ming-Yang Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+Y">Yi-Xi Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+H">Hui-Nan Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+G">Guang-Bing Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yao%2C+Q">Quan Yao</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+X">Xiu-Ping Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+H">Hao Qin</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Fei-Hu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">Juan Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+Y">Yuan Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2408.04361v2-abstract-short" style="display: inline;"> The entangled photons are crucial resources for quantum communications and networking. Here, we present an ultra-bright polarization-entangled photon source based on a periodically poled lithium niobate waveguide designed for practical quantum communication networks. Using a 780 nm pump laser, the source achieves a pair generation rate of 2.4 $\times 10^{10}$ pairs/s/mW. This work has achieved a d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04361v2-abstract-full').style.display = 'inline'; document.getElementById('2408.04361v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.04361v2-abstract-full" style="display: none;"> The entangled photons are crucial resources for quantum communications and networking. Here, we present an ultra-bright polarization-entangled photon source based on a periodically poled lithium niobate waveguide designed for practical quantum communication networks. Using a 780 nm pump laser, the source achieves a pair generation rate of 2.4 $\times 10^{10}$ pairs/s/mW. This work has achieved a directly measured power of 17.9 nW in entangled photon generation with a 3.2 mW pump power. Based on this, we demonstrate the practicality of the source by conducting quantum key distribution experiments over long-distance fiber links, achieving the applicable secure key rates of up to 440.80 bits/s over 200 km with 62 dB loss and reaching a maximum secure key generation distance of 404 km. These results demonstrate the potential of wavelength-multiplexed polarization-entangled photon sources for high-speed, long-distance quantum communication, positioning them as key components for future large-scale quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.04361v2-abstract-full').style.display = 'none'; document.getElementById('2408.04361v2-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 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 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/2406.03222">arXiv:2406.03222</a> <span> [<a href="https://arxiv.org/pdf/2406.03222">pdf</a>, <a href="https://arxiv.org/format/2406.03222">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"> Solving Sharp Bounded-error Quantum Polynomial Time Problem by Evolution methods </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Z">Zhen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.03222v2-abstract-short" style="display: inline;"> Counting ground state degeneracy of a $k$-local Hamiltonian is important in many fields of physics. Its complexity belongs to the problem of sharp bounded-error quantum polynomial time (#BQP) class and few methods are known for its solution. Finding ground states of a $k$-local Hamiltonian, on the other hand, is an easier problem of Quantum Merlin Arthur (QMA) class, for which many efficient metho… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.03222v2-abstract-full').style.display = 'inline'; document.getElementById('2406.03222v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.03222v2-abstract-full" style="display: none;"> Counting ground state degeneracy of a $k$-local Hamiltonian is important in many fields of physics. Its complexity belongs to the problem of sharp bounded-error quantum polynomial time (#BQP) class and few methods are known for its solution. Finding ground states of a $k$-local Hamiltonian, on the other hand, is an easier problem of Quantum Merlin Arthur (QMA) class, for which many efficient methods exist. In this work, we propose an algorithm of mapping a #BQP problem into one of finding a special ground state of a $k$-local Hamiltonian. We prove that all traditional methods, which solve the QMA problem by evolution under a function of a Hamiltonian, can be used to find the special ground state from a well-designed initial state, thus can solve the #BQP problem. We combine our algorithm with power method, Lanczos method, and quantum imaginary time evolution method for different systems to illustrate the detection of phase boundaries, competition between frustration and quantum fluctuation, and potential implementations with quantum circuits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.03222v2-abstract-full').style.display = 'none'; document.getElementById('2406.03222v2-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.12999">arXiv:2402.12999</a> <span> [<a href="https://arxiv.org/pdf/2402.12999">pdf</a>, <a href="https://arxiv.org/format/2402.12999">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"> Robust single divacancy defects near stacking faults in 4H-SiC under resonant excitation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=He%2C+Z">Zhen-Xuan He</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Ji-Yang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+W">Wu-Xi Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qiang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+R">Rui-Jian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jun-Feng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wen%2C+X">Xiao-Lei Wen</a>, <a href="/search/quant-ph?searchtype=author&query=Hao%2C+Z">Zhi-He Hao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wei Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Ren%2C+S">Shuo Ren</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">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+J">Jian-Shun Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jin-Shi Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.12999v1-abstract-short" style="display: inline;"> Color centers in silicon carbide (SiC) have demonstrated significant promise for quantum information processing. However, the undesirable ionization process that occurs during optical manipulation frequently causes fluctuations in the charge state and performance of these defects, thereby restricting the effectiveness of spin-photon interfaces. Recent predictions indicate that divacancy defects ne… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.12999v1-abstract-full').style.display = 'inline'; document.getElementById('2402.12999v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.12999v1-abstract-full" style="display: none;"> Color centers in silicon carbide (SiC) have demonstrated significant promise for quantum information processing. However, the undesirable ionization process that occurs during optical manipulation frequently causes fluctuations in the charge state and performance of these defects, thereby restricting the effectiveness of spin-photon interfaces. Recent predictions indicate that divacancy defects near stacking faults possess the capability to stabilize their neutral charge states, thereby providing robustness against photoionization effects. In this work, we present a comprehensive protocol for the scalable and targeted fabrication of single divacancy arrays in 4H-SiC using a high-resolution focused helium ion beam. Through photoluminescence emission (PLE) experiments, we demonstrate long-term emission stability with minimal linewidth shift ($\sim$ 50 MHz over 3 hours) for the single c-axis divacancies within stacking faults. By measuring the ionization rate for different polytypes of divacancies, we found that the divacancies within stacking faults are more robust against resonant excitation. Additionally, angle-resolved PLE spectra reveal their two resonant-transition lines with mutually orthogonal polarizations. Notably, the PLE linewidths are approximately 7 times narrower and the spin-coherent times are 6 times longer compared to divacancies generated via carbon-ion implantation. These findings highlight the immense potential of SiC divacancies for on-chip quantum photonics and the construction of efficient spin-to-photon interfaces, indicating a significant step forward in the development of quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.12999v1-abstract-full').style.display = 'none'; document.getElementById('2402.12999v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.08888">arXiv:2402.08888</a> <span> [<a href="https://arxiv.org/pdf/2402.08888">pdf</a>, <a href="https://arxiv.org/format/2402.08888">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum Light Generation based on GaN Microring towards Fully On-chip Source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+H">Hong Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Z">Zhao-Qin He</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yun-Ru Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Y">Yue Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Lyu%2C+C">Chen Lyu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Jin-Peng Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yun-Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Sheng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+D">Dong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+D">De-Chao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+J">Juan-Juan Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guang-Wei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Hai-Zhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+K">Kai Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+C">Chang-Zheng Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Y">Yi Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.08888v1-abstract-short" style="display: inline;"> Integrated quantum light source is increasingly desirable in large-scale quantum information processing.~Despite recent remarkable advances, new material platform is constantly being explored for the fully on-chip integration of quantum light generation, active and passive manipulation, and detection. Here, for the first time, we demonstrate a gallium nitride (GaN) microring based quantum light ge… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.08888v1-abstract-full').style.display = 'inline'; document.getElementById('2402.08888v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.08888v1-abstract-full" style="display: none;"> Integrated quantum light source is increasingly desirable in large-scale quantum information processing.~Despite recent remarkable advances, new material platform is constantly being explored for the fully on-chip integration of quantum light generation, active and passive manipulation, and detection. Here, for the first time, we demonstrate a gallium nitride (GaN) microring based quantum light generation in the telecom C-band, which has potential towards the monolithic integration of quantum light source.~In our demonstration, the GaN microring has a free spectral range of 330 GHz and a near-zero anomalous dispersion region of over 100 nm. The generation of energy-time entangled photon pair is demonstrated with a typical raw two-photon interference visibility of 95.5$\pm$6.5%, which is further configured to generate heralded single photon with a typical heralded second-order auto-correlation $g^{(2)}_{H}(0)$ of 0.045$\pm$0.001. Our results pave the way for developing chip-scale quantum photonic circuit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.08888v1-abstract-full').style.display = 'none'; document.getElementById('2402.08888v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.00005">arXiv:2402.00005</a> <span> [<a href="https://arxiv.org/pdf/2402.00005">pdf</a>, <a href="https://arxiv.org/format/2402.00005">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/s44214-023-00039-9">10.1007/s44214-023-00039-9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> 1002 km Twin-Field Quantum Key Distribution with Finite-Key Analysis </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+D">Di Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+W">Wen-Xin Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+H">Hao Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Xiong%2C+J">Jia-Min Xiong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Cheng-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=Wang%2C+R">Rui-Chun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Jun Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.00005v1-abstract-short" style="display: inline;"> Quantum key distribution (QKD) holds the potential to establish secure keys over long distances. The distance of point-to-point QKD secure key distribution is primarily impeded by the transmission loss inherent to the channel. In the quest to realize a large-scale quantum network, increasing the QKD distance under current technology is of great research interest. Here we adopt the 3-intensity send… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00005v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00005v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00005v1-abstract-full" style="display: none;"> Quantum key distribution (QKD) holds the potential to establish secure keys over long distances. The distance of point-to-point QKD secure key distribution is primarily impeded by the transmission loss inherent to the channel. In the quest to realize a large-scale quantum network, increasing the QKD distance under current technology is of great research interest. Here we adopt the 3-intensity sending-or-not-sending twin-field QKD (TF-QKD) protocol with the actively-odd-parity-pairing method. The experiment demonstrates the feasibility of secure QKD over a 1002 km fibre channel considering the finite size effect. The secure key rate is $3.11\times10^{-12}$ per pulse at this distance. Furthermore, by optimizing parameters for shorter fiber distances, we conducted performance tests on key distribution for fiber lengths ranging from 202 km to 505 km. Notably, the secure key rate for the 202 km, the normal distance between major cities, reached 111.74 kbps. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00005v1-abstract-full').style.display = 'none'; document.getElementById('2402.00005v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Front 2, 16 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.10697">arXiv:2401.10697</a> <span> [<a href="https://arxiv.org/pdf/2401.10697">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Reconfigurable entanglement distribution network based on pump management of spontaneous four-wave mixing source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+J">Jingyuan Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+D">Dongning Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Z">Zhanping Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+Z">Zhihao Lin</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=Feng%2C+X">Xue Feng</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+F">Fang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Cui%2C+K">Kaiyu Cui</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yidong Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei 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="2401.10697v1-abstract-short" style="display: inline;"> Leveraging the unique properties of quantum entanglement, quantum entanglement distribution networks support multiple quantum information applications and are essential to the development of quantum networks. However, its practical implementation poses significant challenges to network scalability and flexibility. In this work, we propose a novel reconfigurable entanglement distribution network ba… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10697v1-abstract-full').style.display = 'inline'; document.getElementById('2401.10697v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.10697v1-abstract-full" style="display: none;"> Leveraging the unique properties of quantum entanglement, quantum entanglement distribution networks support multiple quantum information applications and are essential to the development of quantum networks. However, its practical implementation poses significant challenges to network scalability and flexibility. In this work, we propose a novel reconfigurable entanglement distribution network based on tunable multi-pump excitation of a spontaneous four-wave mixing (SFWM) source and a time-sharing method. We characterize the two-photon correlation under different pump conditions to demonstrate the effect of pump degenerate and pump non-degenerate SFWM processes on the two-photon correlation, and its tunability. Then as a benchmark application, a 10-user fully-connected quantum key distribution (QKD) network is established in a time-sharing way with triple pump lights. Each user receives one frequency channel thus it shows a linear scaling between the number of frequency channels and the user number in despite of the network topology. Our results thus provide a promising networking scheme for large-scale entanglement distribution networks owing to its scalability, functionality, and reconfigurability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.10697v1-abstract-full').style.display = 'none'; document.getElementById('2401.10697v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 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/2401.04470">arXiv:2401.04470</a> <span> [<a href="https://arxiv.org/pdf/2401.04470">pdf</a>, <a href="https://arxiv.org/format/2401.04470">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="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Single-Shot Readout of a Nuclear Spin in Silicon Carbide </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lai%2C+X">Xiao-Yi Lai</a>, <a href="/search/quant-ph?searchtype=author&query=Fang%2C+R">Ren-Zhou Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+T">Tao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+R">Ren-Zhu Su</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</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">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Bao%2C+X">Xiao-Hui Bao</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="2401.04470v1-abstract-short" style="display: inline;"> Solid-state qubits with a photonic interface is very promising for quantum networks. Color centers in silicon carbide have shown excellent optical and spin coherence, even when integrated with membranes and nano-structures. Additionally, nuclear spins coupled with electron spins can serve as long-lived quantum memories. Pioneering work in previous has realized the initialization of a single nuclea… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04470v1-abstract-full').style.display = 'inline'; document.getElementById('2401.04470v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04470v1-abstract-full" style="display: none;"> Solid-state qubits with a photonic interface is very promising for quantum networks. Color centers in silicon carbide have shown excellent optical and spin coherence, even when integrated with membranes and nano-structures. Additionally, nuclear spins coupled with electron spins can serve as long-lived quantum memories. Pioneering work in previous has realized the initialization of a single nuclear spin and demonstrated its entanglement with an electron spin. In this paper, we report the first realization of single-shot readout for a nuclear spin in SiC. We obtain a deterministic readout fidelity of 98.2% with a measurement duration of 1.13 ms. With a dual-step readout scheme, we obtain a readout fidelity as high as 99.5% with a success efficiency of 89.8%. Our work complements the experimental toolbox of harnessing both electron and nuclear spins in SiC for future quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04470v1-abstract-full').style.display = 'none'; document.getElementById('2401.04470v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.10480">arXiv:2312.10480</a> <span> [<a href="https://arxiv.org/pdf/2312.10480">pdf</a>, <a href="https://arxiv.org/format/2312.10480">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </div> </div> <p class="title is-5 mathjax"> Joint estimation of a two-phase spin rotation beyond classical limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+J">Jiahao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xinwei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+T">Tianwei Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+W">Wenxin Xu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.10480v1-abstract-short" style="display: inline;"> Quantum metrology employs entanglement to enhance measurement precision. The focus and progress so far have primarily centered on estimating a single parameter. In diverse application scenarios, the estimation of more than one single parameter is often required. Joint estimation of multiple parameters can benefit from additional advantages for further enhanced precision. Here we report quantum-enh… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10480v1-abstract-full').style.display = 'inline'; document.getElementById('2312.10480v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.10480v1-abstract-full" style="display: none;"> Quantum metrology employs entanglement to enhance measurement precision. The focus and progress so far have primarily centered on estimating a single parameter. In diverse application scenarios, the estimation of more than one single parameter is often required. Joint estimation of multiple parameters can benefit from additional advantages for further enhanced precision. Here we report quantum-enhanced measurement of simultaneous spin rotations around two orthogonal axes, making use of spin-nematic squeezing in an atomic Bose-Einstein condensate. Aided by the $F=2$ atomic ground hyperfine manifold coupled to the nematic-squeezed $F=1$ states as an auxiliary field through a sequence of microwave (MW) pulses, simultaneous measurement of multiple spin-1 observables is demonstrated, reaching an enhancement of 3.3 to 6.3 decibels (dB) beyond the classical limit over a wide range of rotation angles. Our work realizes the first enhanced multi-parameter estimation using entangled massive particles as a probe. The techniques developed and the protocols implemented also highlight the application of two-mode squeezed vacuum states in quantum-enhanced sensing of noncommuting spin rotations simultaneously. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10480v1-abstract-full').style.display = 'none'; document.getElementById('2312.10480v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.17455">arXiv:2311.17455</a> <span> [<a href="https://arxiv.org/pdf/2311.17455">pdf</a>, <a href="https://arxiv.org/format/2311.17455">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="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> </div> <p class="title is-5 mathjax"> Experimental Generation of Spin-Photon Entanglement in Silicon Carbide </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Fang%2C+R">Ren-Zhou Fang</a>, <a href="/search/quant-ph?searchtype=author&query=Lai%2C+X">Xiao-Yi Lai</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+T">Tao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+R">Ren-Zhu Su</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+B">Bo-Wei Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+C">Chao-Wei Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+Y">Yu-Kun Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Cheng Li</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Z">Zhi-Gang He</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</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">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Bao%2C+X">Xiao-Hui Bao</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.17455v1-abstract-short" style="display: inline;"> A solid-state approach for quantum networks is advantages, as it allows the integration of nanophotonics to enhance the photon emission and the utilization of weakly coupled nuclear spins for long-lived storage. Silicon carbide, specifically point defects within it, shows great promise in this regard due to the easy of availability and well-established nanofabrication techniques. Despite of remark… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.17455v1-abstract-full').style.display = 'inline'; document.getElementById('2311.17455v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.17455v1-abstract-full" style="display: none;"> A solid-state approach for quantum networks is advantages, as it allows the integration of nanophotonics to enhance the photon emission and the utilization of weakly coupled nuclear spins for long-lived storage. Silicon carbide, specifically point defects within it, shows great promise in this regard due to the easy of availability and well-established nanofabrication techniques. Despite of remarkable progresses made, achieving spin-photon entanglement remains a crucial aspect to be realized. In this paper, we experimentally generate entanglement between a silicon vacancy defect in silicon carbide and a scattered single photon in the zero-phonon line. The spin state is measured by detecting photons scattered in the phonon sideband. The photonic qubit is encoded in the time-bin degree-of-freedom and measured using an unbalanced Mach-Zehnder interferometer. Photonic correlations not only reveal the quality of the entanglement but also verify the deterministic nature of the entanglement creation process. By harnessing two pairs of such spin-photon entanglement, it becomes straightforward to entangle remote quantum nodes at long distance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.17455v1-abstract-full').style.display = 'none'; document.getElementById('2311.17455v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages in total, 4 figures in the main text, 1 figure in the 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/2310.18292">arXiv:2310.18292</a> <span> [<a href="https://arxiv.org/pdf/2310.18292">pdf</a>, <a href="https://arxiv.org/format/2310.18292">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"> Twin-field quantum key distribution with local frequency reference </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+F">Fei Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fa-Xi Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</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">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</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+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="2310.18292v1-abstract-short" style="display: inline;"> Twin-field quantum key distribution (TF-QKD) overcomes the linear rate-loss limit, which promises a boost of secure key rate over long distance. However, the complexity of eliminating the frequency differences between the independent laser sources hinders its practical application. Here, taking the saturated absorption spectroscopy of acetylene as an absolute reference, we propose and demonstrate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.18292v1-abstract-full').style.display = 'inline'; document.getElementById('2310.18292v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.18292v1-abstract-full" style="display: none;"> Twin-field quantum key distribution (TF-QKD) overcomes the linear rate-loss limit, which promises a boost of secure key rate over long distance. However, the complexity of eliminating the frequency differences between the independent laser sources hinders its practical application. Here, taking the saturated absorption spectroscopy of acetylene as an absolute reference, we propose and demonstrate a simple and practical approach to realize TF-QKD without requiring relative frequency control of the independent laser sources. Adopting the 4-intensity sending-or-not-sending TF-QKD protocol, we experimentally demonstrate the TF-QKD over 502 km, 301 km and 201 km ultra-low loss optical fiber respectively. We expect this high-performance scheme will find widespread usage in future intercity and free-space quantum communication networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.18292v1-abstract-full').style.display = 'none'; document.getElementById('2310.18292v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 5 figures, 7 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 132, 260802 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.14546">arXiv:2310.14546</a> <span> [<a href="https://arxiv.org/pdf/2310.14546">pdf</a>, <a href="https://arxiv.org/format/2310.14546">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum Hamiltonian Algorithms for Maximum Independent Sets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+X">Xianjue Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Ge%2C+P">Peiyun Ge</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Hongye Yu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a>, <a href="/search/quant-ph?searchtype=author&query=Wilczek%2C+F">Frank Wilczek</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+B">Biao 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="2310.14546v5-abstract-short" style="display: inline;"> With qubits encoded into atomic ground and Rydberg states and situated on the vertexes of a graph, the conditional quantum dynamics of Rydberg blockade, which inhibits simultaneous excitation of nearby atoms, has been employed recently to find maximum independent sets following an adiabatic evolution algorithm hereafter denoted by HV [Science 376, 1209 (2022)]. An alternative algorithm, short name… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.14546v5-abstract-full').style.display = 'inline'; document.getElementById('2310.14546v5-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.14546v5-abstract-full" style="display: none;"> With qubits encoded into atomic ground and Rydberg states and situated on the vertexes of a graph, the conditional quantum dynamics of Rydberg blockade, which inhibits simultaneous excitation of nearby atoms, has been employed recently to find maximum independent sets following an adiabatic evolution algorithm hereafter denoted by HV [Science 376, 1209 (2022)]. An alternative algorithm, short named the PK algorithm, reveals that the independent sets diffuse over a media graph governed by a non-abelian gauge matrix of an emergent PXP model. This work shows the above two algorithms are mathematically equivalent, despite of their seemingly different physical implementations. More importantly, we demonstrated that although the two are mathematically equivalent, the PK algorithm exhibits more efficient and resource-saving performance. Within the same range of experimental parameters, our numerical studies suggest that the PK algorithm performs at least 25% better on average and saves at least $6\times10^6$ measurements ($\sim 900$ hours of continuous operation) for each graph when compared to the HV algorithm. We further consider the measurement error and point out that this may cause the oscillations in the performance of the HV's optimization process. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.14546v5-abstract-full').style.display = 'none'; document.getElementById('2310.14546v5-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 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">7pages, 6figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.09176">arXiv:2307.09176</a> <span> [<a href="https://arxiv.org/pdf/2307.09176">pdf</a>, <a href="https://arxiv.org/format/2307.09176">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> </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.131.073201">10.1103/PhysRevLett.131.073201 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of entangled states supported by reinforcement learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Cao%2C+J">Jia-Hao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Feng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+T">Tian-Wei Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+W">Wen-Xin Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+L">Ling-Na Wu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.09176v1-abstract-short" style="display: inline;"> Discrimination of entangled states is an important element of quantum enhanced metrology. This typically requires low-noise detection technology. Such a challenge can be circumvented by introducing nonlinear readout process. Traditionally, this is realized by reversing the very dynamics that generates the entangled state, which requires a full control over the system evolution. In this work, we pr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.09176v1-abstract-full').style.display = 'inline'; document.getElementById('2307.09176v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.09176v1-abstract-full" style="display: none;"> Discrimination of entangled states is an important element of quantum enhanced metrology. This typically requires low-noise detection technology. Such a challenge can be circumvented by introducing nonlinear readout process. Traditionally, this is realized by reversing the very dynamics that generates the entangled state, which requires a full control over the system evolution. In this work, we present nonlinear readout of highly entangled states by employing reinforcement learning (RL) to manipulate the spin-mixing dynamics in a spin-1 atomic condensate. The RL found results in driving the system towards an unstable fixed point, whereby the (to be sensed) phase perturbation is amplified by the subsequent spin-mixing dynamics. Working with a condensate of 10900 {87}^Rb atoms, we achieve a metrological gain of 6.97 dB beyond the classical precision limit. Our work would open up new possibilities in unlocking the full potential of entanglement caused quantum enhancement in experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.09176v1-abstract-full').style.display = 'none'; document.getElementById('2307.09176v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 131, 073201 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.04531">arXiv:2307.04531</a> <span> [<a href="https://arxiv.org/pdf/2307.04531">pdf</a>, <a href="https://arxiv.org/format/2307.04531">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 quantum non-Gaussian coincidences of entangled photons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+Y">Yu-Kun Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Lachman%2C+L">Luk谩拧 Lachman</a>, <a href="/search/quant-ph?searchtype=author&query=Ge%2C+Z">Zhen-Xuan Ge</a>, <a href="/search/quant-ph?searchtype=author&query=Chung%2C+T">Tung-Hsun Chung</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+J">Jun-Yi Zhao</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=Filip%2C+R">Radim Filip</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.04531v2-abstract-short" style="display: inline;"> Quantum non-Gaussianity, a more potent and highly useful form of nonclassicality, excludes all convex mixtures of Gaussian states and Gaussian parametric processes generating them. Here, for the first time, we conclusively test quantum non-Gaussian coincidences of entangled photon pairs with the CHSH-Bell factor $S=2.328\pm0.004$ from a single quantum dot with a depth up to $0.94\pm 0.02$ dB. Such… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.04531v2-abstract-full').style.display = 'inline'; document.getElementById('2307.04531v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.04531v2-abstract-full" style="display: none;"> Quantum non-Gaussianity, a more potent and highly useful form of nonclassicality, excludes all convex mixtures of Gaussian states and Gaussian parametric processes generating them. Here, for the first time, we conclusively test quantum non-Gaussian coincidences of entangled photon pairs with the CHSH-Bell factor $S=2.328\pm0.004$ from a single quantum dot with a depth up to $0.94\pm 0.02$ dB. Such deterministically generated photon pairs fundamentally overcome parametric processes by reducing crucial multiphoton errors. For the quantum non-Gaussian depth of the unheralded (heralded) single-photon state, we achieve the value of $8.08\pm0.05$ dB ($19.06\pm0.29$ dB). Our work experimentally certifies the exclusive quantum non-Gaussianity properties highly relevant for optical sensing, communication and computation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.04531v2-abstract-full').style.display = 'none'; document.getElementById('2307.04531v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.02364">arXiv:2307.02364</a> <span> [<a href="https://arxiv.org/pdf/2307.02364">pdf</a>, <a href="https://arxiv.org/format/2307.02364">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/s41566-023-01166-4">10.1038/s41566-023-01166-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-rate quantum key distribution exceeding 110 Mb/s </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=Zhang%2C+L">Likang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+H">Hao Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yichen Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+H">Hao-Kun Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+B">Bingze Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qiong Li</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+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</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="2307.02364v1-abstract-short" style="display: inline;"> Quantum key distribution (QKD) can provide fundamentally proven security for secure communication. Toward application, the secret key rate (SKR) is a key figure of merit for any QKD system. So far, the SKR has been limited to about a few megabit-per-second. Here we report a QKD system that is able to generate key at a record high SKR of 115.8 Mb/s over 10-km standard fibre, and to distribute key o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02364v1-abstract-full').style.display = 'inline'; document.getElementById('2307.02364v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.02364v1-abstract-full" style="display: none;"> Quantum key distribution (QKD) can provide fundamentally proven security for secure communication. Toward application, the secret key rate (SKR) is a key figure of merit for any QKD system. So far, the SKR has been limited to about a few megabit-per-second. Here we report a QKD system that is able to generate key at a record high SKR of 115.8 Mb/s over 10-km standard fibre, and to distribute key over up to 328 km of ultra-low-loss fibre. This attributes to a multi-pixel superconducting nanowire single-photon detector with ultrahigh counting rate, an integrated transmitter that can stably encode polarization states with low error, a fast post-processing algorithm for generating key in real time and the high system clock-rate operation. The results demonstrate the feasibility of practical high-rate QKD with photonic techniques, thus opening its possibility for widespread applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.02364v1-abstract-full').style.display = 'none'; document.getElementById('2307.02364v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Photonics 17, 416-421 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.08229">arXiv:2306.08229</a> <span> [<a href="https://arxiv.org/pdf/2306.08229">pdf</a>, <a href="https://arxiv.org/format/2306.08229">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"> Telecom-band integrated multimode photonic quantum memory </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xueying Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+B">Bin Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+S">Shihai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+J">Jinyu Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Cheng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guangwei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Haizhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Jing%2C+B">Bo Jing</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Feng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</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="2306.08229v1-abstract-short" style="display: inline;"> Telecom-band integrated quantum memory is an elementary building block for developing quantum networks compatible with fiber communication infrastructures. Towards such a network with large capacity, an integrated multimode photonic quantum memory at telecom band has yet been demonstrated. Here we report a fiber-integrated multimode quantum storage of single photon at telecom band on a laser-writt… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08229v1-abstract-full').style.display = 'inline'; document.getElementById('2306.08229v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.08229v1-abstract-full" style="display: none;"> Telecom-band integrated quantum memory is an elementary building block for developing quantum networks compatible with fiber communication infrastructures. Towards such a network with large capacity, an integrated multimode photonic quantum memory at telecom band has yet been demonstrated. Here we report a fiber-integrated multimode quantum storage of single photon at telecom band on a laser-written chip. The storage device is a fiber-pigtailed Er3+:LiNbO3 waveguide and allows a storage of up to 330 temporal modes of heralded single photon with 4-GHz-wide bandwidth at 1532 nm and a 167-fold increasing of coincidence detection rate with respect to single mode. Our memory system with all-fiber addressing is performed using telecom-band fiber-integrated and on-chip devices. The results represent an important step for the future quantum networks using integrated photonics devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08229v1-abstract-full').style.display = 'none'; document.getElementById('2306.08229v1-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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.20070">arXiv:2305.20070</a> <span> [<a href="https://arxiv.org/pdf/2305.20070">pdf</a>, <a href="https://arxiv.org/format/2305.20070">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-024-02542-9">10.1038/s41567-024-02542-9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dissipative time crystal in a strongly interacting Rydberg gas </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+X">Xiaoling Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhuqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+F">Fan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Gao%2C+R">Ruochen Gao</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+C">Chao Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Tey%2C+M+K">Meng Khoon Tey</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangliang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Pohl%2C+T">Thomas Pohl</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.20070v3-abstract-short" style="display: inline;"> The notion of spontaneous symmetry breaking has been well established to characterize classical and quantum phase transitions of matter, such as in condensation, crystallization or quantum magnetism. Generalizations of this paradigm to the time dimension can lead to a time crystal phase, which spontaneously breaks the time translation symmetry of the system. Whereas the existence of a continuous t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.20070v3-abstract-full').style.display = 'inline'; document.getElementById('2305.20070v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.20070v3-abstract-full" style="display: none;"> The notion of spontaneous symmetry breaking has been well established to characterize classical and quantum phase transitions of matter, such as in condensation, crystallization or quantum magnetism. Generalizations of this paradigm to the time dimension can lead to a time crystal phase, which spontaneously breaks the time translation symmetry of the system. Whereas the existence of a continuous time crystal at equilibrium has been challenged by no-go theorems, this difficulty can be circumvented by dissipation in an open system. Here, we report the experimental observation of such dissipative time crystalline order in a room-temperature atomic gas, where ground-state atoms are continuously driven to Rydberg states. The emergent time crystal is revealed by persistent oscillations of the photon transmission, and we show that the observed limit cycles arise from the coexistence and competition between distinct Rydberg components. The nondecaying autocorrelation of the oscillation, together with the robustness against temporal noises, indicate the establishment of true long-range temporal order and demonstrates the realization of a continuous time crystal. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.20070v3-abstract-full').style.display = 'none'; document.getElementById('2305.20070v3-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">v1</span> submitted 31 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 4+6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Phys. 20, 1389 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.18696">arXiv:2305.18696</a> <span> [<a href="https://arxiv.org/pdf/2305.18696">pdf</a>, <a href="https://arxiv.org/format/2305.18696">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"> Energy-time Entanglement Coexisting with Fiber Optical Communication at Telecom C-band </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yun-Ru Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Y">Yue Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zi-Chang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yun-Bo Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+S">Sheng Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+D">Dong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+D">Dechao Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guang-Wei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Hai-Zhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chen-Zhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.18696v1-abstract-short" style="display: inline;"> The coexistence of quantum and classical light in the same fiber link is extremely desired in developing quantum communication. It has been implemented for different quantum information tasks, such as classical light coexisting with polarization-entangled photons at telecom O-band, and with quantum signal based quantum key distribution (QKD). In this work, we demonstrate the coexistence of energy-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.18696v1-abstract-full').style.display = 'inline'; document.getElementById('2305.18696v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.18696v1-abstract-full" style="display: none;"> The coexistence of quantum and classical light in the same fiber link is extremely desired in developing quantum communication. It has been implemented for different quantum information tasks, such as classical light coexisting with polarization-entangled photons at telecom O-band, and with quantum signal based quantum key distribution (QKD). In this work, we demonstrate the coexistence of energy-time entanglement based QKD and fiber optical communication at the telecom C-band. The property of noise from the classical channel is characterized with classical light at different wavelengths. With the largest noise, i.e., the worst case, the properties of energy-time entanglement are measured at different fiber optical communication rates. By measuring the two-photon interference of energy-time entanglement, our results show that a visibility of 82.01$\pm$1.10\% is achieved with a bidirectional 20 Gbps fiber optical communication over 40 km. Furthermore, by performing the BBM92 protocol for QKD, a secret key rate of 245 bits per second could be generated with a quantum bit error rate of 8.88\% with the coexisted energy-time entanglement.~Our demonstration paves the way for developing the infrastructure for quantum networks compatible with fiber optical communication. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.18696v1-abstract-full').style.display = 'none'; document.getElementById('2305.18696v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 3 figures,</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.03244">arXiv:2305.03244</a> <span> [<a href="https://arxiv.org/pdf/2305.03244">pdf</a>, <a href="https://arxiv.org/format/2305.03244">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.3c00568">10.1021/acs.nanolett.3c00568 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Plasmonic-enhanced bright single spin defects in silicon carbide membranes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Ji-Yang Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qiang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Hao%2C+Z">Zhi-He Hao</a>, <a href="/search/quant-ph?searchtype=author&query=Lin%2C+W">Wu-Xi Lin</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Z">Zhen-Xuan He</a>, <a href="/search/quant-ph?searchtype=author&query=Liang%2C+R">Rui-Jian Liang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+L">Liping Guo</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=Tang%2C+J">Jian-Shun Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jin-Shi Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.03244v1-abstract-short" style="display: inline;"> Optically addressable spin defects in silicon carbide (SiC) have emerged as attractable platforms for various quantum technologies. However, the low photon count rate significantly limits their applications. We strongly enhanced the brightness by 7 times and spin-control strength by 14 times of single divacancy defects in 4H-SiC membranes using surface plasmon generated by gold film coplanar waveg… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.03244v1-abstract-full').style.display = 'inline'; document.getElementById('2305.03244v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.03244v1-abstract-full" style="display: none;"> Optically addressable spin defects in silicon carbide (SiC) have emerged as attractable platforms for various quantum technologies. However, the low photon count rate significantly limits their applications. We strongly enhanced the brightness by 7 times and spin-control strength by 14 times of single divacancy defects in 4H-SiC membranes using surface plasmon generated by gold film coplanar waveguides. The mechanism of the plasmonic-enhanced effect is further studied by tuning the distance between single defects and the surface of the gold film. A three-energy-level model is used to determine the corresponding transition rates consistent with the enhanced brightness of single defects. Lifetime measurements also verified the coupling between defects and surface plasmons. Our scheme is low-cost, without complicated microfabrication and delicate structures, which is applicable for other spin defects in different materials. This work would promote developing spin defect-based quantum applications in mature SiC materials. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.03244v1-abstract-full').style.display = 'none'; document.getElementById('2305.03244v1-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.14245">arXiv:2304.14245</a> <span> [<a href="https://arxiv.org/pdf/2304.14245">pdf</a>, <a href="https://arxiv.org/format/2304.14245">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1364/OL.489656">10.1364/OL.489656 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discrete frequency-bin entanglement generation via cascaded second-order nonlinear processes in Sagnac interferometer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+J">Jiarui Li</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chenzhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+S">Si Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zichang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Ruiming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guangwei Deng</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=Song%2C+H">Haizhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yunru Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guangcan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</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="2304.14245v1-abstract-short" style="display: inline;"> Discrete frequency-bin entanglement is an essential resource for applications in quantum information processing. In this Letter, we propose and demonstrate a scheme to generate discrete frequency-bin entanglement with a single piece of periodically poled lithium niobate waveguide in a modified Sagnac interferometer. Correlated two-photon states in both directions of the Sagnac interferometer are g… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.14245v1-abstract-full').style.display = 'inline'; document.getElementById('2304.14245v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.14245v1-abstract-full" style="display: none;"> Discrete frequency-bin entanglement is an essential resource for applications in quantum information processing. In this Letter, we propose and demonstrate a scheme to generate discrete frequency-bin entanglement with a single piece of periodically poled lithium niobate waveguide in a modified Sagnac interferometer. Correlated two-photon states in both directions of the Sagnac interferometer are generated through cascaded second-order optical nonlinear processes. A relative phase difference between the two states is introduced by changing the polarization state of pump light, thus manipulating the two-photon state at the output of the Sagnac interferometer. The generated two-photon state is sent into a fiber polarization splitter, then a pure discrete frequency-bin entangled two-photon state is obtained by setting the pump light. The frequency entanglement property is measured by a spatial quantum beating with a visibility of $96.0 \pm 6.1\%$. The density matrix is further obtained with a fidelity of $98.0 \pm 3.0\%$ to the ideal state. Our demonstration provides a promising method for the generation of pure discrete frequency-bin entanglement at telecom band, which is desired in quantum photonics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.14245v1-abstract-full').style.display = 'none'; document.getElementById('2304.14245v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">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> Opt. Lett. 48, 2917-2920 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.12240">arXiv:2304.12240</a> <span> [<a href="https://arxiv.org/pdf/2304.12240">pdf</a>, <a href="https://arxiv.org/format/2304.12240">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"> Gaussian Boson Sampling with Pseudo-Photon-Number Resolving Detectors and Quantum Computational Advantage </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Deng%2C+Y">Yu-Hao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+Y">Yi-Chao Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hua-Liang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+S">Si-Qiu Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+H">Hao Su</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhi-Jiong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+H">Hao-Yang Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+M">Meng-Hao Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jia-Min Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+J">Jian Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+L">Li-Chao Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+J">Jiarong Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Y">Yi Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yuxuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+Y">Yaojian Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Gan%2C+L">Lin Gan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+G">Guangwen Yang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+L">Li Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+H">Han-Sen Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Hui Wang</a> , et al. (4 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="2304.12240v3-abstract-short" style="display: inline;"> We report new Gaussian boson sampling experiments with pseudo-photon-number-resolving detection, which register up to 255 photon-click events. We consider partial photon distinguishability and develop a more complete model for the characterization of the noisy Gaussian boson sampling. In the quantum computational advantage regime, we use Bayesian tests and correlation function analysis to validate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.12240v3-abstract-full').style.display = 'inline'; document.getElementById('2304.12240v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.12240v3-abstract-full" style="display: none;"> We report new Gaussian boson sampling experiments with pseudo-photon-number-resolving detection, which register up to 255 photon-click events. We consider partial photon distinguishability and develop a more complete model for the characterization of the noisy Gaussian boson sampling. In the quantum computational advantage regime, we use Bayesian tests and correlation function analysis to validate the samples against all current classical mockups. Estimating with the best classical algorithms to date, generating a single ideal sample from the same distribution on the supercomputer Frontier would take ~ 600 years using exact methods, whereas our quantum computer, Jiuzhang 3.0, takes only 1.27 us to produce a sample. Generating the hardest sample from the experiment using an exact algorithm would take Frontier ~ 3.1*10^10 years. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.12240v3-abstract-full').style.display = 'none'; document.getElementById('2304.12240v3-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">PRL 2023 to appear</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.11841">arXiv:2304.11841</a> <span> [<a href="https://arxiv.org/pdf/2304.11841">pdf</a>, <a href="https://arxiv.org/format/2304.11841">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.13.021028">10.1103/PhysRevX.13.021028 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Performing SU($d$) operations and rudimentary algorithms in a superconducting transmon qudit for $d=3$ and $d=4$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+P">Pei Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+R">Ruixia Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jing-Ning Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yingshan Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Cai%2C+X">Xiaoxia Cai</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+H">Huikai Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zhiyuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+J">Jiaxiu Han</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xuegang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+G">Guangming Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Weiyang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+Y">Yirong Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Haifeng Yu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.11841v1-abstract-short" style="display: inline;"> Quantum computation architecture based on $d$-level systems, or qudits, has attracted considerable attention recently due to their enlarged Hilbert space. Extensive theoretical and experimental studies have addressed aspects of algorithms and benchmarking techniques for qudit-based quantum computation and quantum information processing. Here, we report a physical realization of qudit with upto 4 e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11841v1-abstract-full').style.display = 'inline'; document.getElementById('2304.11841v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.11841v1-abstract-full" style="display: none;"> Quantum computation architecture based on $d$-level systems, or qudits, has attracted considerable attention recently due to their enlarged Hilbert space. Extensive theoretical and experimental studies have addressed aspects of algorithms and benchmarking techniques for qudit-based quantum computation and quantum information processing. Here, we report a physical realization of qudit with upto 4 embedded levels in a superconducting transmon, demonstrating high-fidelity initialization, manipulation, and simultaneous multi-level readout. In addition to constructing SU($d$) operations and benchmarking protocols for quantum state tomography, quantum process tomography, and randomized benchmarking etc, we experimentally carry out these operations for $d=3$ and $d=4$. Moreover, we perform prototypical quantum algorithms and observe outcomes consistent with expectations. Our work will hopefully stimulate further research interest in developing manipulation protocols and efficient applications for quantum processors with qudits. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11841v1-abstract-full').style.display = 'none'; document.getElementById('2304.11841v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Submitted to the Physical Review X; Received 19 October 2022; accepted 3 April 2023</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. X 13, 021028 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.08866">arXiv:2304.08866</a> <span> [<a href="https://arxiv.org/pdf/2304.08866">pdf</a>, <a href="https://arxiv.org/format/2304.08866">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </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.107.052613">10.1103/PhysRevA.107.052613 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cyclic nonlinear interferometry with entangled non-Gaussian spin states </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+T">Tian-Wei Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Xue%2C+M">Ming Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+L">Ling-Na Wu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.08866v1-abstract-short" style="display: inline;"> We propose an efficient nonlinear readout scheme for entangled non-Gaussian spin states (ENGSs) based on the intrinsic quasi-cyclic dynamics of interacting spin-1/2 systems. We focus on two well-known spin models of twist-and-turn (TNT) and two-axis-counter-twisting (TACT), where ENGS can be generated by spin dynamics starting from unstable fixed points. In the TNT model, non-Gaussian probe state… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.08866v1-abstract-full').style.display = 'inline'; document.getElementById('2304.08866v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.08866v1-abstract-full" style="display: none;"> We propose an efficient nonlinear readout scheme for entangled non-Gaussian spin states (ENGSs) based on the intrinsic quasi-cyclic dynamics of interacting spin-1/2 systems. We focus on two well-known spin models of twist-and-turn (TNT) and two-axis-counter-twisting (TACT), where ENGS can be generated by spin dynamics starting from unstable fixed points. In the TNT model, non-Gaussian probe state evolves directly back to the vicinity of initial state during the subsequent time-forward evolution for path recombining, accompanied by quantum magnification of encoded signal and refocusing of the associated quantum noise. Based on low-order moment measurement, we find the optimal metrological gain nearly saturates the quantum Cramer-Rao bound (QCRB) and follows the Heisenberg scaling. For the TACT case, the QCRB can also be nearly approached when the state converges to either of the two unstable fixed points, respectively corresponding to the initial state or its orthogonal coherent state. The latter case goes beyond previous studies where tracing back to or crossing the initial states is mostly considered. The present protocol does not require time-reversal as in typical nonlinear interferometries, and it also avoids complicated measurement of nonlinear observables or full probability distributions. The operational approach we discuss presents a practical way for realizing high-precision and detection-noise-robust quantum metrology with ENGS. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.08866v1-abstract-full').style.display = 'none'; document.getElementById('2304.08866v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 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. A 107, 052613 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.15795">arXiv:2303.15795</a> <span> [<a href="https://arxiv.org/pdf/2303.15795">pdf</a>, <a href="https://arxiv.org/format/2303.15795">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.210801">10.1103/PhysRevLett.130.210801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Twin-Field Quantum Key Distribution Over 1000 km Fiber Distance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+W">Wen-Xin Pan</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+D">Di Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Dong%2C+H">Hao Dong</a>, <a href="/search/quant-ph?searchtype=author&query=Xiong%2C+J">Jia-Min Xiong</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Cheng-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=Wang%2C+R">Rui-Chun Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+J">Jun Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.15795v1-abstract-short" style="display: inline;"> Quantum key distribution (QKD) aims to generate secure private keys shared by two remote parties. With its security being protected by principles of quantum mechanics, some technology challenges remain towards practical application of QKD. The major one is the distance limit, which is caused by the fact that a quantum signal cannot be amplified while the channel loss is exponential with the distan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.15795v1-abstract-full').style.display = 'inline'; document.getElementById('2303.15795v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.15795v1-abstract-full" style="display: none;"> Quantum key distribution (QKD) aims to generate secure private keys shared by two remote parties. With its security being protected by principles of quantum mechanics, some technology challenges remain towards practical application of QKD. The major one is the distance limit, which is caused by the fact that a quantum signal cannot be amplified while the channel loss is exponential with the distance for photon transmission in optical fiber. Here using the 3-intensity sending-or-not-sending protocol with the actively-odd-parity-pairing method, we demonstrate a fiber-based twin-field QKD over 1002 km. In our experiment, we developed a dual-band phase estimation and ultra-low noise superconducting nanowire single-photon detectors to suppress the system noise to around 0.02 Hz. The secure key rate is $9.53\times10^{-12}$ per pulse through 1002 km fiber in the asymptotic regime, and $8.75\times10^{-12}$ per pulse at 952 km considering the finite size effect. Our work constitutes a critical step towards the future large-scale quantum network. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.15795v1-abstract-full').style.display = 'none'; document.getElementById('2303.15795v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">47 pages, 17 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. 130, 210801 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.13866">arXiv:2303.13866</a> <span> [<a href="https://arxiv.org/pdf/2303.13866">pdf</a>, <a href="https://arxiv.org/format/2303.13866">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/s41377-023-01158-7">10.1038/s41377-023-01158-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hertz-rate metropolitan quantum teleportation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Shen%2C+S">Si Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chenzhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zichang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Hao Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Ruiming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+C">Chuanrong Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guangwei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Haizhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yunru Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guangcan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.13866v1-abstract-short" style="display: inline;"> Quantum teleportation can transfer an unknown quantum state between distant quantum nodes, which holds great promise in enabling large-scale quantum networks. To advance the full potential of quantum teleportation, quantum states must be faithfully transferred at a high rate over long distance. Despite recent impressive advances, a high-rate quantum teleportation system across metropolitan fiber n… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.13866v1-abstract-full').style.display = 'inline'; document.getElementById('2303.13866v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.13866v1-abstract-full" style="display: none;"> Quantum teleportation can transfer an unknown quantum state between distant quantum nodes, which holds great promise in enabling large-scale quantum networks. To advance the full potential of quantum teleportation, quantum states must be faithfully transferred at a high rate over long distance. Despite recent impressive advances, a high-rate quantum teleportation system across metropolitan fiber networks is extremely desired. Here, we demonstrate a quantum teleportation system which transfers quantum states carried by independent photons at a rate of 7.1$\pm$0.4 Hz over 64-km-long fiber channel. An average single-photon fidelity of $\geqslant$ 90.6$\pm$2.6% is achieved, which exceeds the maximum fidelity of 2/3 in classical regime. Our result marks an important milestone towards quantum networks and opens the door to exploring quantum entanglement based informatic applications for the future quantum internet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.13866v1-abstract-full').style.display = 'none'; document.getElementById('2303.13866v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">35 pages, 10 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Light: Science & Applications Vol. 12, Issue 1, pp. 115 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.00936">arXiv:2302.00936</a> <span> [<a href="https://arxiv.org/pdf/2302.00936">pdf</a>, <a href="https://arxiv.org/format/2302.00936">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/PhysRevLett.130.190601">10.1103/PhysRevLett.130.190601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Solving Graph Problems Using Gaussian Boson Sampling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Deng%2C+Y">Yu-Hao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+S">Si-Qiu Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Gu%2C+Y">Yi-Chao Gu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zhi-Jiong Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hua-Liang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+H">Hao Su</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+H">Hao-Yang Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jia-Min Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Jia%2C+M">Meng-Hao Jia</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+H">Han-Sen Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Hui Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+J">Jiarong Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Y">Yi Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</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=Jiang%2C+X">Xiao Jiang</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=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=Lu%2C+C">Chao-Yang Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2302.00936v2-abstract-short" style="display: inline;"> Gaussian boson sampling (GBS) is not only a feasible protocol for demonstrating quantum computational advantage, but also mathematically associated with certain graph-related and quantum chemistry problems. In particular, it is proposed that the generated samples from the GBS could be harnessed to enhance the classical stochastic algorithms in searching some graph features. Here, we use Jiuzhang,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.00936v2-abstract-full').style.display = 'inline'; document.getElementById('2302.00936v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.00936v2-abstract-full" style="display: none;"> Gaussian boson sampling (GBS) is not only a feasible protocol for demonstrating quantum computational advantage, but also mathematically associated with certain graph-related and quantum chemistry problems. In particular, it is proposed that the generated samples from the GBS could be harnessed to enhance the classical stochastic algorithms in searching some graph features. Here, we use Jiuzhang, a noisy intermediate-scale quantum computer, to solve graph problems. The samples are generated from a 144-mode fully-connected photonic processor, with photon-click up to 80 in the quantum computational advantage regime. We investigate the open question of whether the GBS enhancement over the classical stochastic algorithms persists -- and how it scales -- with an increasing system size on noisy quantum devices in the computationally interesting regime. We experimentally observe the presence of GBS enhancement with large photon-click number and a robustness of the enhancement under certain noise. Our work is a step toward testing real-world problems using the existing noisy intermediate-scale quantum computers, and hopes to stimulate the development of more efficient classical and quantum-inspired algorithms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.00936v2-abstract-full').style.display = 'none'; document.getElementById('2302.00936v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.09124">arXiv:2212.09124</a> <span> [<a href="https://arxiv.org/pdf/2212.09124">pdf</a>, <a href="https://arxiv.org/format/2212.09124">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum enhanced sensing by echoing spin-nematic squeezing in atomic Bose-Einstein condensate </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mao%2C+T">Tian-Wei Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xin-Wei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+J">Jia-Hao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Feng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+W">Wen-Xin Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Tey%2C+M+K">Meng Khoon Tey</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yi-Xiao Huang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.09124v1-abstract-short" style="display: inline;"> Quantum entanglement can provide enhanced precision beyond standard quantum limit (SQL), the highest precision achievable with classical means. It remains challenging, however, to observe large enhancement limited by the experimental abilities to prepare, maintain, manipulate and detect entanglement. Here, we present nonlinear interferometry protocols based on echoing spin-nematic squeezing to ach… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.09124v1-abstract-full').style.display = 'inline'; document.getElementById('2212.09124v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.09124v1-abstract-full" style="display: none;"> Quantum entanglement can provide enhanced precision beyond standard quantum limit (SQL), the highest precision achievable with classical means. It remains challenging, however, to observe large enhancement limited by the experimental abilities to prepare, maintain, manipulate and detect entanglement. Here, we present nonlinear interferometry protocols based on echoing spin-nematic squeezing to achieve record high enhancement factors in atomic Bose-Einstein condensate. The echo is realized by a state-flip of the spin-nematic squeezed vacuum, which serves as the probe state and is refocused back to the vicinity of the unsqueezed initial state while carrying out near noiseless amplification of a signal encoded. A sensitivity of $21.6\pm0.5$ decibels (dB) for a small-angle Rabi rotation beyond the two-mode SQL of 26400 atoms as well as $16.6\pm1.3$ dB for phase sensing in a Ramsey interferometer are observed. The absolute phase sensitivity for the latter extrapolates to $103~\rm{pT/\sqrt{Hz}}$ at a probe volume of $18~渭\rm{m}^3$ for near-resonant microwave field sensing. Our work highlights the excellent many-body coherence of spin-nematic squeezing and suggests its possible quantum metrological applications in atomic magnetometer, atomic optical clock, and fundamental testing of Lorentz symmetry violation, etc. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.09124v1-abstract-full').style.display = 'none'; document.getElementById('2212.09124v1-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.04829">arXiv:2212.04829</a> <span> [<a href="https://arxiv.org/pdf/2212.04829">pdf</a>, <a href="https://arxiv.org/ps/2212.04829">ps</a>, <a href="https://arxiv.org/format/2212.04829">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Enhanced measurement precision with continuous interrogation during dynamical decoupling </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+J">Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Du%2C+P">Peng Du</a>, <a href="/search/quant-ph?searchtype=author&query=Jing%2C+L">Lei Jing</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+P">Peng Xu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wenxian 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="2212.04829v2-abstract-short" style="display: inline;"> Dynamical decoupling (DD) is normally ineffective when applied to DC measurement. In its straightforward implementation, DD nulls out DC signal as well while suppressing noise. This work proposes a phase relay method (PRM) that is capable of continuously interrogating the DC signal over many DD cycles. We illustrate its efficacy when applied to measurement of a weak DC magnetic field with an atomi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.04829v2-abstract-full').style.display = 'inline'; document.getElementById('2212.04829v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.04829v2-abstract-full" style="display: none;"> Dynamical decoupling (DD) is normally ineffective when applied to DC measurement. In its straightforward implementation, DD nulls out DC signal as well while suppressing noise. This work proposes a phase relay method (PRM) that is capable of continuously interrogating the DC signal over many DD cycles. We illustrate its efficacy when applied to measurement of a weak DC magnetic field with an atomic spinor Bose-Einstein condensate. Sensitivities approaching standard quantum limit (SQL) or Heisenberg limit (HL) are potentially realizable for a coherent spin state (CSS) or a squeezed spin state (SSS) of 10,000 atoms respectively, while ambient laboratory level noise is suppressed by DD. Our work offers a practical approach to mitigate the limitations of DD to DC measurement and will like find other applications for resorting coherence in quantum sensing and quantum information processing research. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.04829v2-abstract-full').style.display = 'none'; document.getElementById('2212.04829v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.04311">arXiv:2212.04311</a> <span> [<a href="https://arxiv.org/pdf/2212.04311">pdf</a>, <a href="https://arxiv.org/format/2212.04311">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.250802">10.1103/PhysRevLett.130.250802 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Twin-field quantum key distribution without phase locking </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=Zhang%2C+L">Likang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+Y">Yichen Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Z">Zheng-Ping Li</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+J">Jia Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</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="2212.04311v3-abstract-short" style="display: inline;"> Twin-field quantum key distribution (TF-QKD) has emerged as a promising solution for practical quantum communication over long-haul fiber. However, previous demonstrations on TF-QKD require the phase locking technique to coherently control the twin light fields, inevitably complicating the system with extra fiber channels and peripheral hardware. Here we propose and demonstrate an approach to reco… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.04311v3-abstract-full').style.display = 'inline'; document.getElementById('2212.04311v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.04311v3-abstract-full" style="display: none;"> Twin-field quantum key distribution (TF-QKD) has emerged as a promising solution for practical quantum communication over long-haul fiber. However, previous demonstrations on TF-QKD require the phase locking technique to coherently control the twin light fields, inevitably complicating the system with extra fiber channels and peripheral hardware. Here we propose and demonstrate an approach to recover the single-photon interference pattern and realize TF-QKD \emph{without} phase locking. Our approach separates the communication time into reference frames and quantum frames, where the reference frames serve as a flexible scheme for establishing the global phase reference. To do so, we develop a tailored algorithm based on fast Fourier transform to efficiently reconcile the phase reference via data post-processing. We demonstrate no-phase-locking TF-QKD from short to long distances over standard optical fibers. At 50-km standard fiber, we produce a high secret key rate (SKR) of 1.27 Mbit/s, while at 504-km standard fiber, we obtain the repeater-like key rate scaling with a SKR of 34 times higher than the repeaterless secret key capacity. Our work provides a scalable and practical solution to TF-QKD, thus representing an important step towards its wide applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.04311v3-abstract-full').style.display = 'none'; document.getElementById('2212.04311v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 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">Published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 130, 250802 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.14858">arXiv:2210.14858</a> <span> [<a href="https://arxiv.org/pdf/2210.14858">pdf</a>, <a href="https://arxiv.org/format/2210.14858">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Variational Matrix Product State Approach for Non-Hermitian System Based on a Companion Hermitian Hamiltonian </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Guo%2C+Z">Zhen Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zheng-Tao Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+M">Meng Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo Yang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.14858v1-abstract-short" style="display: inline;"> Non-Hermitian systems exhibiting topological properties are attracting growing interest. In this work, we propose an algorithm for solving the ground state of a non-Hermitian system in the matrix product state (MPS) formalism based on a companion Hermitian Hamiltonian. If the eigenvalues of the non-Hermitian system are known, the companion Hermitian Hamiltonian can be directly constructed and solv… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.14858v1-abstract-full').style.display = 'inline'; document.getElementById('2210.14858v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.14858v1-abstract-full" style="display: none;"> Non-Hermitian systems exhibiting topological properties are attracting growing interest. In this work, we propose an algorithm for solving the ground state of a non-Hermitian system in the matrix product state (MPS) formalism based on a companion Hermitian Hamiltonian. If the eigenvalues of the non-Hermitian system are known, the companion Hermitian Hamiltonian can be directly constructed and solved using Hermitian variational methods. When the eigenvalues are unknown, a gradient descent along with the companion Hermitian Hamiltonian yields both the ground state eigenenergy and the eigenstate. With the variational principle as a solid foundation, our algorithm ensures convergence and provides results in excellent agreement with the exact solutions of the non-Hermitian Su-Schrieffer-Heeger (nH-SSH) model as well as its interacting extension. The approach we present avoids solving any non-Hermitian matrix and overcomes numerical instabilities commonly encountered in large non-Hermitian systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.14858v1-abstract-full').style.display = 'none'; document.getElementById('2210.14858v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 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/2210.04034">arXiv:2210.04034</a> <span> [<a href="https://arxiv.org/pdf/2210.04034">pdf</a>, <a href="https://arxiv.org/ps/2210.04034">ps</a>, <a href="https://arxiv.org/format/2210.04034">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="General Relativity and Quantum Cosmology">gr-qc</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1367-2630/ac926e">10.1088/1367-2630/ac926e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Entanglement and quantum teleportation under superposed gravitational fields </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yue Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+B">Baocheng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.04034v1-abstract-short" style="display: inline;"> The influence of gravitational field on entanglement of bipartite states is investigated based on the recent idea of superposition states of gravitational field. Different from earlier considerations, we study the case where the gravitational field cannot be separated unitarily from the bipartite system in the final stage of the interaction. When the different gravitational field states are orthog… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.04034v1-abstract-full').style.display = 'inline'; document.getElementById('2210.04034v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.04034v1-abstract-full" style="display: none;"> The influence of gravitational field on entanglement of bipartite states is investigated based on the recent idea of superposition states of gravitational field. Different from earlier considerations, we study the case where the gravitational field cannot be separated unitarily from the bipartite system in the final stage of the interaction. When the different gravitational field states are orthogonal, entanglement cannot be generated for an initial product state. If the different gravitational field states are non-orthogonal, entanglement can be generated and the amount of generated entanglement depends on an overlap parameter between different gravitational field states. The influence of gravitational field on the transfer of the state through quantum teleportation is also studied, which might lead to an observable effect since the quantum teleportation can be performed using macroscopic object. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.04034v1-abstract-full').style.display = 'none'; document.getElementById('2210.04034v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> New J. Phys. 24 (2022) 093034 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.11417">arXiv:2209.11417</a> <span> [<a href="https://arxiv.org/pdf/2209.11417">pdf</a>, <a href="https://arxiv.org/format/2209.11417">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-quality multi-wavelength quantum light sources on silicon nitride micro-ring chip </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Fan%2C+Y">Yun-Ru Fan</a>, <a href="/search/quant-ph?searchtype=author&query=Lyu%2C+C">Chen Lyu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chen-Zhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guang-Wei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Z">Zhi-Yuan Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Geng%2C+Y">Yong Geng</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Hai-Zhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Y">Yan-Feng Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Jin%2C+R">Rui-Bo Jin</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+H">Heng Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.11417v1-abstract-short" style="display: inline;"> Multi-wavelength quantum light sources, especially at telecom band, are extremely desired in quantum information technology. Despite recent impressive advances, such a quantum light source with high quality remains challenging. Here we demonstrate a multi-wavelength quantum light source using a silicon nitride micro-ring with a free spectral range of 200 GHz. The generation of eight pairs of corre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.11417v1-abstract-full').style.display = 'inline'; document.getElementById('2209.11417v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.11417v1-abstract-full" style="display: none;"> Multi-wavelength quantum light sources, especially at telecom band, are extremely desired in quantum information technology. Despite recent impressive advances, such a quantum light source with high quality remains challenging. Here we demonstrate a multi-wavelength quantum light source using a silicon nitride micro-ring with a free spectral range of 200 GHz. The generation of eight pairs of correlated photons is ensured in a wavelength range of 25.6 nm. With device optimization and noise-rejecting filters, our source enables the generation of heralded single-photons - at a rate of 62 kHz with $g^{(2)}_{h}(0)=0.014\pm0.001$, and the generation of energy-time entangled photons - with a visibility of $99.39\pm 0.45\%$ in the Franson interferometer. These results, at room temperature and telecom wavelength, in a CMOS compatible platform, represent an important step towards integrated quantum light devices for the quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.11417v1-abstract-full').style.display = 'none'; document.getElementById('2209.11417v1-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 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/2209.00802">arXiv:2209.00802</a> <span> [<a href="https://arxiv.org/pdf/2209.00802">pdf</a>, <a href="https://arxiv.org/format/2209.00802">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Quantum storage of 1650 modes of single photons at telecom wavelength </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wei%2C+S">Shi-Hai Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Jing%2C+B">Bo Jing</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+X">Xue-Ying Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+J">Jin-Yu Liao</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">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guang-Wei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Hai-Zhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Oblak%2C+D">Daniel Oblak</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.00802v2-abstract-short" style="display: inline;"> To advance the full potential of quantum networks one should be able to distribute quantum resources over long distances at appreciable rates. As a consequence, all components in the networks need to have large multimode capacity to manipulate photonic quantum states. Towards this end, a multimode photonic quantum memory, especially one operating at telecom wavelength, remains a key challenge. Her… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.00802v2-abstract-full').style.display = 'inline'; document.getElementById('2209.00802v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.00802v2-abstract-full" style="display: none;"> To advance the full potential of quantum networks one should be able to distribute quantum resources over long distances at appreciable rates. As a consequence, all components in the networks need to have large multimode capacity to manipulate photonic quantum states. Towards this end, a multimode photonic quantum memory, especially one operating at telecom wavelength, remains a key challenge. Here we demonstrate a spectro-temporally multiplexed quantum memory at 1532 nm. Multimode quantum storage of telecom-band heralded single photons is realized by employing the atomic frequency comb protocol in a 10-m-long cryogenically cooled erbium doped silica fibre. The multiplexing encompasses five spectral channels - each 10 GHz wide - and in each of these up to 330 temporal modes, resulting in the simultaneous storage of 1650 modes of single photons. Our demonstrations open doors for high-rate quantum networks, which are essential for future quantum internet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.00802v2-abstract-full').style.display = 'none'; document.getElementById('2209.00802v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.05649">arXiv:2208.05649</a> <span> [<a href="https://arxiv.org/pdf/2208.05649">pdf</a>, <a href="https://arxiv.org/format/2208.05649">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.130.030801">10.1103/PhysRevLett.130.030801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental mode-pairing measurement-device-independent quantum key distribution without global phase-locking </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhu%2C+H">Hao-Tao Zhu</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+Y">Yizhi Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hui Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zeng%2C+P">Pei Zeng</a>, <a href="/search/quant-ph?searchtype=author&query=Zou%2C+M">Mi Zou</a>, <a href="/search/quant-ph?searchtype=author&query=Dai%2C+Y">Yunqi Dai</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+S">Shibiao Tang</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=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=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="2208.05649v2-abstract-short" style="display: inline;"> In the past two decades, quantum key distribution networks based on telecom fibers have been implemented on metropolitan and intercity scales. One of the bottlenecks lies in the exponential decay of the key rate with respect to the transmission distance. Recently proposed schemes mainly focus on achieving longer distances by creating a long-arm single-photon interferometer over two communication p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.05649v2-abstract-full').style.display = 'inline'; document.getElementById('2208.05649v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.05649v2-abstract-full" style="display: none;"> In the past two decades, quantum key distribution networks based on telecom fibers have been implemented on metropolitan and intercity scales. One of the bottlenecks lies in the exponential decay of the key rate with respect to the transmission distance. Recently proposed schemes mainly focus on achieving longer distances by creating a long-arm single-photon interferometer over two communication parties. Despite their advantageous performance over long communication distances, the requirement of phase-locking between two independent lasers is technically challenging. By adopting the recently-proposed mode-pairing idea, we realize high-performance quantum key distribution without global phase-locking. Using two independent off-the-shelf lasers, we show a quadratic key-rate improvement over the conventional measurement-device-independent schemes in the regime of metropolitan and intercity distances. For longer distances, we also boost the key rate performance by three orders of magnitude via 304 km commercial fiber and 407 km ultra-low-loss fiber. We expect this ready-to-implement high-performance scheme to be widely used in future intercity quantum communication networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.05649v2-abstract-full').style.display = 'none'; document.getElementById('2208.05649v2-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 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 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">19 pages, 9 figures, 7 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 130, 030801 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.09609">arXiv:2204.09609</a> <span> [<a href="https://arxiv.org/pdf/2204.09609">pdf</a>, <a href="https://arxiv.org/format/2204.09609">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.106.033708">10.1103/PhysRevA.106.033708 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Controlling atomic spin-mixing via multiphoton transitions in a cavity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xue%2C+M">Ming Xue</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xiangliang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Ye%2C+W">Wenhao Ye</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jun-Jie Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+Z">Zhi-Fang Xu</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.09609v1-abstract-short" style="display: inline;"> We propose to control spin-mixing dynamics in a gas of spinor atoms, via the combination of two off-resonant Raman transition pathways, enabled by a common cavity mode and a bichromatic pump laser. The mixing rate, which is proportional to the synthesized spin-exchange interaction strength, and the effective atomic quadratic Zeeman shift (QZS), can both be tuned by changing the pump laser paramete… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09609v1-abstract-full').style.display = 'inline'; document.getElementById('2204.09609v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.09609v1-abstract-full" style="display: none;"> We propose to control spin-mixing dynamics in a gas of spinor atoms, via the combination of two off-resonant Raman transition pathways, enabled by a common cavity mode and a bichromatic pump laser. The mixing rate, which is proportional to the synthesized spin-exchange interaction strength, and the effective atomic quadratic Zeeman shift (QZS), can both be tuned by changing the pump laser parameters. Quench and driving dynamics of the atomic collective spin are shown to be controllable on a faster time scale than in existing experiments based on inherent spin-exchange collision interactions. The results we present open a promising avenue for exploring spin-mixing physics of atomic ensembles accessible in current experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.09609v1-abstract-full').style.display = 'none'; document.getElementById('2204.09609v1-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 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">4.5pages with appendices, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 106, 033708 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.03994">arXiv:2203.03994</a> <span> [<a href="https://arxiv.org/pdf/2203.03994">pdf</a>, <a href="https://arxiv.org/ps/2203.03994">ps</a>, <a href="https://arxiv.org/format/2203.03994">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevResearch.4.L032046">10.1103/PhysRevResearch.4.L032046 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Manipulating synthetic gauge fluxes via multicolor dressing of Rydberg-atom arrays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wu%2C+X">Xiaoling Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+F">Fan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+S">Shuo Yang</a>, <a href="/search/quant-ph?searchtype=author&query=M%C3%B8lmer%2C+K">Klaus M酶lmer</a>, <a href="/search/quant-ph?searchtype=author&query=Pohl%2C+T">Thomas Pohl</a>, <a href="/search/quant-ph?searchtype=author&query=Tey%2C+M+K">Meng Khoon Tey</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.03994v2-abstract-short" style="display: inline;"> Arrays of highly excited Rydberg atoms can be used as powerful quantum simulation platforms. Here, we introduce an approach that makes it possible to implement fully controllable effective spin interactions in such systems. We show that optical Rydberg dressing with multicolor laser fields opens up distinct interaction channels that enable complete site-selective control of the induced interaction… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.03994v2-abstract-full').style.display = 'inline'; document.getElementById('2203.03994v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.03994v2-abstract-full" style="display: none;"> Arrays of highly excited Rydberg atoms can be used as powerful quantum simulation platforms. Here, we introduce an approach that makes it possible to implement fully controllable effective spin interactions in such systems. We show that optical Rydberg dressing with multicolor laser fields opens up distinct interaction channels that enable complete site-selective control of the induced interactions and favorable scaling with respect to decoherence. We apply this method to generate synthetic gauge fields for Rydberg excitations where the effective magnetic flux can be manipulated at the single-plaquette level by simply varying the phase of the local dressing field. The system can be mapped to a highly anisotropic Heisenberg model, and the resulting spin interaction opens the door for explorations of topological phenomena with nonlocal density interactions. A remarkable consequence of the interaction is the emergence of topologically protected long-range doublons, which exhibit strongly correlated motion in a chiral and robust manner. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.03994v2-abstract-full').style.display = 'none'; document.getElementById('2203.03994v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8+11 pages, 5+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. Research 4, L032046 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.00793">arXiv:2111.00793</a> <span> [<a href="https://arxiv.org/pdf/2111.00793">pdf</a>, <a href="https://arxiv.org/format/2111.00793">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-021-01441-7">10.1038/s41567-021-01441-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nonlinear interferometry beyond classical limit facilitated by cyclic dynamics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Q">Qi Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+L">Ling-Na Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Cao%2C+J">Jia-Hao Cao</a>, <a href="/search/quant-ph?searchtype=author&query=Mao%2C+T">Tian-Wei Mao</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+X">Xin-Wei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+S">Shuai-Feng Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Tey%2C+M+K">Meng Khoon Tey</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2111.00793v2-abstract-short" style="display: inline;"> Time-reversed evolution has substantial implications in physics, including prominent applications in refocusing of classical waves or spins and fundamental researches such as quantum information scrambling. In quantum metrology, nonlinear interferometry based on time reversal protocols supports entanglement-enhanced measurements without requiring low-noise detection. Despite the broad interest in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.00793v2-abstract-full').style.display = 'inline'; document.getElementById('2111.00793v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.00793v2-abstract-full" style="display: none;"> Time-reversed evolution has substantial implications in physics, including prominent applications in refocusing of classical waves or spins and fundamental researches such as quantum information scrambling. In quantum metrology, nonlinear interferometry based on time reversal protocols supports entanglement-enhanced measurements without requiring low-noise detection. Despite the broad interest in time reversal, it remains challenging to reverse the quantum dynamics of an interacting many-body system as is typically realized by an (effective) sign-flip of the system's Hamiltonian. Here, we present an approach that is broadly applicable to cyclic systems for implementing nonlinear interferometry without invoking time reversal. Inspired by the observation that the time-reversed dynamics drives a system back to its starting point, we propose to accomplish the same by slaving the system to travel along a 'closed-loop' instead of explicitly tracing back its antecedent path. Utilizing the quasi-periodic spin mixing dynamics in a three-mode $^{87}$Rb atom spinor condensate, we implement such a 'closed-loop' nonlinear interferometer and achieve a metrological gain of $3.87_{-0.95}^{+0.91}$ decibels over the classical limit for a total of 26500 atoms. Our approach unlocks the high potential of nonlinear interferometry by allowing the dynamics to penetrate into deep nonlinear regime, which gives rise to highly entangled non-Gaussian state. The idea of bypassing time reversal may open up new opportunities in the experimental investigation of researches that are typically studied by using time reversal protocols. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.00793v2-abstract-full').style.display = 'none'; document.getElementById('2111.00793v2-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 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics 18, 167-171 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.11671">arXiv:2110.11671</a> <span> [<a href="https://arxiv.org/pdf/2110.11671">pdf</a>, <a href="https://arxiv.org/format/2110.11671">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.128.180502">10.1103/PhysRevLett.128.180502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum key distribution over 658 km fiber with distributed vibration sensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+D">Dong-Feng Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+F">Fa-Xi Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing 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">Yang Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.11671v1-abstract-short" style="display: inline;"> Twin-field quantum key distribution (TF-QKD) promises ultra-long secure key distribution which surpasses the rate distance limit and can reduce the number of the trusted nodes in long-haul quantum network. Tremendous efforts have been made towards implementation of TF-QKD, among which, the secure key with finite size analysis can distribute more than 500 km in the lab and in the field. Here, we de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11671v1-abstract-full').style.display = 'inline'; document.getElementById('2110.11671v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.11671v1-abstract-full" style="display: none;"> Twin-field quantum key distribution (TF-QKD) promises ultra-long secure key distribution which surpasses the rate distance limit and can reduce the number of the trusted nodes in long-haul quantum network. Tremendous efforts have been made towards implementation of TF-QKD, among which, the secure key with finite size analysis can distribute more than 500 km in the lab and in the field. Here, we demonstrate the sending-or-not-sending TF-QKD experimentally, achieving a secure key distribution with finite size analysis over 658 km ultra-low-loss optical fiber, improve the secure distance record by around 100 km. Meanwhile, in a TF-QKD system, any phase fluctuation due to temperature variation and ambient variation during the channel must be recorded and compensated, and all these phase information can then be utilized to sense the channel vibration perturbations. With our QKD system, we recovered the external vibrational perturbations on the fiber generated by an artificial vibroseis and successfully located the perturbation position with a resolution better than 1 km. Our results not only set a new distance record of QKD, but also demonstrate that the redundant information of TF-QKD can be used for remote sensing of the channel vibration, which can find applications in earthquake detection and landslide monitoring besides secure communication. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.11671v1-abstract-full').style.display = 'none'; document.getElementById('2110.11671v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 4 figures and 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 128, 180502 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.15545">arXiv:2106.15545</a> <span> [<a href="https://arxiv.org/pdf/2106.15545">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Quantum interference between independent solid-state single-photon sources separated by 300 km fiber </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=You%2C+X">Xiang You</a>, <a href="/search/quant-ph?searchtype=author&query=Zheng%2C+M">Ming-Yang Zheng</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+S">Si Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+R">Run-Ze Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+J">Jian Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+M+-">M. -C. Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Ge%2C+Z+-">Z. -X. Ge</a>, <a href="/search/quant-ph?searchtype=author&query=Chung%2C+T+-">T. -H. Chung</a>, <a href="/search/quant-ph?searchtype=author&query=Qiao%2C+Y+-">Y. -K. Qiao</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+Y+-">Y. -F. Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+H+-">H. -S. Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M+-">M. -C. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">H. Wang</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+Y+-">Y. -M. He</a>, <a href="/search/quant-ph?searchtype=author&query=Xie%2C+X+-">X. -P. Xie</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">H. Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L+-">L. -X. You</a>, <a href="/search/quant-ph?searchtype=author&query=Schneider%2C+C">C. Schneider</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+J">J. Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T+-">T. -Y. Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Benyoucef%2C+M">M. Benyoucef</a>, <a href="/search/quant-ph?searchtype=author&query=Huo%2C+Y">Yong-Heng Huo</a>, <a href="/search/quant-ph?searchtype=author&query=Hoefling%2C+S">S. Hoefling</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</a> , et al. (1 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="2106.15545v1-abstract-short" style="display: inline;"> In the quest to realize a scalable quantum network, semiconductor quantum dots (QDs) offer distinct advantages including high single-photon efficiency and indistinguishability, high repetition rate (tens of GHz with Purcell enhancement), interconnectivity with spin qubits, and a scalable on-chip platform. However, in the past two decades, the visibility of quantum interference between independent… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.15545v1-abstract-full').style.display = 'inline'; document.getElementById('2106.15545v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.15545v1-abstract-full" style="display: none;"> In the quest to realize a scalable quantum network, semiconductor quantum dots (QDs) offer distinct advantages including high single-photon efficiency and indistinguishability, high repetition rate (tens of GHz with Purcell enhancement), interconnectivity with spin qubits, and a scalable on-chip platform. However, in the past two decades, the visibility of quantum interference between independent QDs rarely went beyond the classical limit of 50$\%$ and the distances were limited from a few meters to kilometers. Here, we report quantum interference between two single photons from independent QDs separated by 302 km optical fiber. The single photons are generated from resonantly driven single QDs deterministically coupled to microcavities. Quantum frequency conversions are used to eliminate the QD inhomogeneity and shift the emission wavelength to the telecommunication band. The observed interference visibility is 0.67$\pm$0.02 (0.93$\pm$0.04) without (with) temporal filtering. Feasible improvements can further extend the distance to 600 km. Our work represents a key step to long-distance solid-state quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.15545v1-abstract-full').style.display = 'none'; document.getElementById('2106.15545v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 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">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/2106.15534">arXiv:2106.15534</a> <span> [<a href="https://arxiv.org/pdf/2106.15534">pdf</a>, <a href="https://arxiv.org/format/2106.15534">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.127.180502">10.1103/PhysRevLett.127.180502 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phase-Programmable Gaussian Boson Sampling Using Stimulated Squeezed Light </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+H">Han-Sen Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+Y">Yu-Hao Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Qin%2C+J">Jian Qin</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Hui Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+M">Ming-Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+L">Li-Chao Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Luo%2C+Y">Yi-Han Luo</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+D">Dian Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Gong%2C+S">Si-Qiu Gong</a>, <a href="/search/quant-ph?searchtype=author&query=Su%2C+H">Hao Su</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+Y">Yi Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+P">Peng Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+X">Xiao-Yan Yang</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=Li%2C+Y">Yuxuan Li</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Gan%2C+L">Lin Gan</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+G">Guangwen Yang</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=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=Renema%2C+J">Jelmer Renema</a>, <a href="/search/quant-ph?searchtype=author&query=Lu%2C+C">Chao-Yang Lu</a> , et al. (1 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="2106.15534v2-abstract-short" style="display: inline;"> The tantalizing promise of quantum computational speedup in solving certain problems has been strongly supported by recent experimental evidence from a high-fidelity 53-qubit superconducting processor1 and Gaussian boson sampling (GBS) with up to 76 detected photons. Analogous to the increasingly sophisticated Bell tests that continued to refute local hidden variable theories, quantum computationa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.15534v2-abstract-full').style.display = 'inline'; document.getElementById('2106.15534v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.15534v2-abstract-full" style="display: none;"> The tantalizing promise of quantum computational speedup in solving certain problems has been strongly supported by recent experimental evidence from a high-fidelity 53-qubit superconducting processor1 and Gaussian boson sampling (GBS) with up to 76 detected photons. Analogous to the increasingly sophisticated Bell tests that continued to refute local hidden variable theories, quantum computational advantage tests are expected to provide increasingly compelling experimental evidence against the Extended Church-Turing thesis. In this direction, continued competition between upgraded quantum hardware and improved classical simulations is required. Here, we report a new GBS experiment that produces up to 113 detection events out of a 144-mode photonic circuit. We develop a new high-brightness and scalable quantum light source, exploring the idea of stimulated squeezed photons, which has simultaneously near-unity purity and efficiency. This GBS is programmable by tuning the phase of the input squeezed states. We demonstrate a new method to efficiently validate the samples by inferring from computationally friendly subsystems, which rules out hypotheses including distinguishable photons and thermal states. We show that our noisy GBS experiment passes the nonclassicality test using an inequality, and we reveal non-trivial genuine high-order correlation in the GBS samples, which are evidence of robustness against possible classical simulation schemes. The photonic quantum computer, Jiuzhang 2.0, yields a Hilbert space dimension up to $10^{43}$, and a sampling rate $10^{24}$ faster than using brute-force simulation on supercomputers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.15534v2-abstract-full').style.display = 'none'; document.getElementById('2106.15534v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 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">23 pages, 6 figures. Comments are welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.12089">arXiv:2104.12089</a> <span> [<a href="https://arxiv.org/pdf/2104.12089">pdf</a>, <a href="https://arxiv.org/format/2104.12089">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/PhysRevB.104.125305">10.1103/PhysRevB.104.125305 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Temperature dependence of divacancy spin coherence in implanted silicon carbide </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lin%2C+W">Wu-Xi Lin</a>, <a href="/search/quant-ph?searchtype=author&query=Yan%2C+F">Fei-Fei Yan</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Q">Qiang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+J">Jun-feng Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Hao%2C+Z">Zhi-He Hao</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+J">Ji-Yang Zhou</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">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+J">Jin-Shi Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chuan-Feng Li</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.12089v3-abstract-short" style="display: inline;"> Spin defects in silicon carbide (SiC) have attracted increasing interest due to their excellent optical and spin properties, which are useful in quantum information processing. In this paper, we systematically investigate the temperature dependence of the spin properties of divacancy defects in implanted 4\emph{H}-SiC. The zero-field splitting parameter $D$, the inhomogeneous dephasing time… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.12089v3-abstract-full').style.display = 'inline'; document.getElementById('2104.12089v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.12089v3-abstract-full" style="display: none;"> Spin defects in silicon carbide (SiC) have attracted increasing interest due to their excellent optical and spin properties, which are useful in quantum information processing. In this paper, we systematically investigate the temperature dependence of the spin properties of divacancy defects in implanted 4\emph{H}-SiC. The zero-field splitting parameter $D$, the inhomogeneous dephasing time $T_2^{*}$, the coherence time $T_2$, and the depolarization time $T_1$ are extensively explored in a temperature range from 5 to 300 K. Two samples implanted with different nitrogen molecule ion fluences ($\rm {N_2}^{+}$, $1\times 10^{14}/\rm cm^{2}$ and $1\times 10^{13}/\rm cm^{2}$) are investigated, whose spin properties are shown to have similar temperature-dependent behaviors. Still, the sample implanted with a lower ion fluence has longer $T_{2}$ and $T_{1}$. We provide possible theoretical explanations for the observed temperature-dependent dynamics. Our work promotes the understanding of the temperature dependence of spin properties in solid-state systems, which can be helpful for constructing wide temperature-range thermometers based on the mature semiconductor material. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.12089v3-abstract-full').style.display = 'none'; document.getElementById('2104.12089v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 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">7 pages, 5 figures, 46 references</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 104, 125305 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.08873">arXiv:2104.08873</a> <span> [<a href="https://arxiv.org/pdf/2104.08873">pdf</a>, <a href="https://arxiv.org/ps/2104.08873">ps</a>, <a href="https://arxiv.org/format/2104.08873">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 Gases">cond-mat.quant-gas</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevA.103.053303">10.1103/PhysRevA.103.053303 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Two-Color Optical Nonlinearity in an Ultracold Rydberg Atom Gas Mixture </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+C">Cheng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Yang%2C+F">Fan Yang</a>, <a href="/search/quant-ph?searchtype=author&query=Wu%2C+X">Xiaoling Wu</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+C">Chuyang Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Tey%2C+M+K">Meng Khoon Tey</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li You</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.08873v1-abstract-short" style="display: inline;"> We report the experimental observation of strong two-color optical nonlinearity in an ultracold gas of $^{85}\mathrm{Rb}$-$^{87}\mathrm{Rb}$ atom mixture. By simultaneously coupling two probe transitions of $^{85}$Rb and $^{87}$Rb atoms to Rydberg states in electromagnetically induced transparency (EIT) configurations, we observe significant suppression of the transparency resonance for one probe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.08873v1-abstract-full').style.display = 'inline'; document.getElementById('2104.08873v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.08873v1-abstract-full" style="display: none;"> We report the experimental observation of strong two-color optical nonlinearity in an ultracold gas of $^{85}\mathrm{Rb}$-$^{87}\mathrm{Rb}$ atom mixture. By simultaneously coupling two probe transitions of $^{85}$Rb and $^{87}$Rb atoms to Rydberg states in electromagnetically induced transparency (EIT) configurations, we observe significant suppression of the transparency resonance for one probe field when the second probe field is detuned at $\sim1~\mathrm{GHz}$ and hitting the EIT resonance of the other isotope. Such a cross-absorption modulation to the beam propagation dynamics can be described by two coupled nonlinear wave equations we develope. We further demonstrate that the two-color optical nonlinearity can be tuned by varying the density ratio of different atomic isotopes, which highlights its potential for exploring strongly interacting multi-component fluids of light. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.08873v1-abstract-full').style.display = 'none'; document.getElementById('2104.08873v1-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 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">6 pages, 4 figures; accepted by Phys. Rev. A (link: https://journals.aps.org/pra/accepted/1507cY42O3711c7412e951d48870d2d3554b4bc8e)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.02593">arXiv:2104.02593</a> <span> [<a href="https://arxiv.org/pdf/2104.02593">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div 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/PRJ.450731">10.1364/PRJ.450731 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spectrally multiplexed heralded single photon source at telecom-band </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Hao Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chenzhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Ruiming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zichang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guangwei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Song%2C+H">Haizhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhiming Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</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="2104.02593v1-abstract-short" style="display: inline;"> Heralded single photon source (HSPS) is an important way in generating genuine single photon, having advantages of experimental simplicity and versatility. However, HSPS intrinsically suffers from the trade-off between the heralded single photon rate and the single photon purity. To overcome this, one can apply multiplexing technology in different degrees of freedom to enhance the performance of H… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.02593v1-abstract-full').style.display = 'inline'; document.getElementById('2104.02593v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.02593v1-abstract-full" style="display: none;"> Heralded single photon source (HSPS) is an important way in generating genuine single photon, having advantages of experimental simplicity and versatility. However, HSPS intrinsically suffers from the trade-off between the heralded single photon rate and the single photon purity. To overcome this, one can apply multiplexing technology in different degrees of freedom to enhance the performance of HSPS. Here, by employing spectral multiplexing and active feed-forward spectral manipulating, we demonstrate a HSPS at 1.5 渭m telecom-band. Our experimental results show that the spectral multiplexing effectively erases the frequency correlation of pair source and significantly improves the heralded single photon rate while keeping the g{^(^2^)}(0) as low as 0.0006{\pm}0.0001. The Hong-Ou-Mandel interference between the heralded single photons and photons from an independent weak coherent source indicates a high indistinguishability. Our results pave a way for scalable HSPS by spectral multiplexing towards deterministic single photon emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.02593v1-abstract-full').style.display = 'none'; document.getElementById('2104.02593v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 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">Main text: 20 pages, 5 figures, 1 table. Supplementary material: 8 pages, 3 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Photonics Research Vol. 10, Issue 6, pp. 1417-1429 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2103.06058">arXiv:2103.06058</a> <span> [<a href="https://arxiv.org/pdf/2103.06058">pdf</a>, <a href="https://arxiv.org/format/2103.06058">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevLett.128.190503">10.1103/PhysRevLett.128.190503 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental Side-Channel-Free Quantum Key Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Long Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Weijun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+Z">Zong-Wen Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Lixing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2103.06058v1-abstract-short" style="display: inline;"> Quantum key distribution can provide unconditionally secure key exchange for remote users in theory. In practice, however, in most quantum key distribution systems, quantum hackers might steal the secure keys by listening to the side channels in the source, such as the photon frequency spectrum, emission time, propagation direction, spatial angular momentum, and so on. It is hard to prevent such k… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.06058v1-abstract-full').style.display = 'inline'; document.getElementById('2103.06058v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2103.06058v1-abstract-full" style="display: none;"> Quantum key distribution can provide unconditionally secure key exchange for remote users in theory. In practice, however, in most quantum key distribution systems, quantum hackers might steal the secure keys by listening to the side channels in the source, such as the photon frequency spectrum, emission time, propagation direction, spatial angular momentum, and so on. It is hard to prevent such kinds of attacks because side channels may exist in any of the encoding space whether the designers take care of or not. Here we report an experimental realization of a side-channel-free quantum key distribution protocol which is not only measurement-device-independent, but also immune to all side-channel attacks in the source. We achieve a secure key rate of 4.80e-7 per pulse through 50 km fiber spools. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2103.06058v1-abstract-full').style.display = 'none'; document.getElementById('2103.06058v1-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 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 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. Lett. 128, 190503 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.07146">arXiv:2102.07146</a> <span> [<a href="https://arxiv.org/pdf/2102.07146">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41534-021-00462-7">10.1038/s41534-021-00462-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High-performance quantum entanglement generation via cascaded second-order nonlinear processes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Z">Zichang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+C">Chenzhi Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Shen%2C+S">Si Shen</a>, <a href="/search/quant-ph?searchtype=author&query=Yu%2C+H">Hao Yu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+R">Ruiming Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+H">Heqing Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Y">You Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Deng%2C+G">Guangwei Deng</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhiming Wang</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=Song%2C+H">Haizhi Song</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guangcan Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+Q">Qiang Zhou</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="2102.07146v1-abstract-short" style="display: inline;"> In this paper, we demonstrate the generation of high-performance entangled photon-pairs in different degrees of freedom from a single piece of fiber pigtailed periodically poled LiNbO$_3$ (PPLN) waveguide. We utilize cascaded second-order nonlinear optical processes, i.e. second-harmonic generation (SHG) and spontaneous parametric down conversion (SPDC), to generate photon-pairs. Previously, the p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.07146v1-abstract-full').style.display = 'inline'; document.getElementById('2102.07146v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.07146v1-abstract-full" style="display: none;"> In this paper, we demonstrate the generation of high-performance entangled photon-pairs in different degrees of freedom from a single piece of fiber pigtailed periodically poled LiNbO$_3$ (PPLN) waveguide. We utilize cascaded second-order nonlinear optical processes, i.e. second-harmonic generation (SHG) and spontaneous parametric down conversion (SPDC), to generate photon-pairs. Previously, the performance of the photon pairs is contaminated by Raman noise photons from the fiber pigtails. Here by integrating the PPLN waveguide with noise rejecting filters, we obtain a coincidence-to-accidental ratio (CAR) higher than 52,600 with photon-pair generation and detection rate of 52.3 kHz and 3.5 kHz, respectively. Energy-time, frequency-bin and time-bin entanglement is prepared by coherently superposing correlated two-photon states in these degrees of freedom, respectively. The energy-time entangled two-photon states achieve the maximum value of CHSH-Bell inequality of S=2.708$\pm$0.024 with a two-photon interference visibility of 95.74$\pm$0.86%. The frequency-bin entangled two-photon states achieve fidelity of 97.56$\pm$1.79% with a spatial quantum beating visibility of 96.85$\pm$2.46%. The time-bin entangled two-photon states achieve the maximum value of CHSH-Bell inequality of S=2.595$\pm$0.037 and quantum tomographic fidelity of 89.07$\pm$4.35%. Our results provide a potential candidate for quantum light source in quantum photonics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.07146v1-abstract-full').style.display = 'none'; document.getElementById('2102.07146v1-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 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">29 pages,7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information volume 7, Article number: 123 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.00433">arXiv:2102.00433</a> <span> [<a href="https://arxiv.org/pdf/2102.00433">pdf</a>, <a href="https://arxiv.org/format/2102.00433">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/s41566-021-00828-5">10.1038/s41566-021-00828-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Twin-Field Quantum Key Distribution over 511 km Optical Fiber Linking two Distant Metropolitans </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jiu-Peng Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+C">Chi Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+C">Cong Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zhi-Yong Han</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+S">Shi-Zhao Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+X">Xiao-Long Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+Y">Yu-Huai Li</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hui Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhou%2C+F">Fei Zhou</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+H">Hai-Feng 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=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+X">Xiang-Bin Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.00433v1-abstract-short" style="display: inline;"> The basic principle of quantum mechanics guarantee the unconditional security of quantum key distribution (QKD) at the cost of inability of amplification of quantum state. As a result, despite remarkable progress in worldwide metropolitan QKD networks over the past decades, long haul fiber QKD network without trustful relay has not been achieved yet. Here, through sending-or-not-sending (SNS) prot… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.00433v1-abstract-full').style.display = 'inline'; document.getElementById('2102.00433v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.00433v1-abstract-full" style="display: none;"> The basic principle of quantum mechanics guarantee the unconditional security of quantum key distribution (QKD) at the cost of inability of amplification of quantum state. As a result, despite remarkable progress in worldwide metropolitan QKD networks over the past decades, long haul fiber QKD network without trustful relay has not been achieved yet. Here, through sending-or-not-sending (SNS) protocol, we complete a twin field QKD (TF-QKD) and distribute secure keys without any trusted repeater over a 511 km long haul fiber trunk linking two distant metropolitans. Our secure key rate is around 3 orders of magnitudes greater than what is expected if the previous QKD field test system over the same length were applied. The efficient quantum-state transmission and stable single-photon interference over such a long distance deployed fiber paves the way to large-scale fiber quantum networks. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.00433v1-abstract-full').style.display = 'none'; document.getElementById('2102.00433v1-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 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">32 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat. Photonics 15, 570 (2021) </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=You%2C+L&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=You%2C+L&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=You%2C+L&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=You%2C+L&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a href="/search/?searchtype=author&query=You%2C+L&start=150" class="pagination-link " aria-label="Page 4" aria-current="page">4 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: 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