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中国物理学会期刊

高速率可扩展型时间复用量子存储的研究

Investigation of high-rate scalable temporal-multimode quantum memory

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  • 光与原子量子记忆纠缠是构建量子中继的核心资源,基于原子系综的Duan-Lukin-Cirac-Zoller过程可产生光与原子记忆(自旋波)量子纠缠,而纠缠对的制备速率直接影响量子中继与通信的效率。空间复用、时间复用以及多模式复用等方案为提升纠缠产生速率提供有效技术途径。本文通过优化声光调制器响应时间、光束脉宽与间隔及信号传输延迟等参数有效缩短实验周期,并基于可扩展型脉冲光制备技术构建了具有高速率可扩展六路时间复用纠缠源。实验结果表明,相较于传统单模纠缠源与非复用纠缠源,该纠缠源光子-原子纠缠(纠缠光子对)产生速率分别提升4.42倍(4.56倍)和5.95倍(5.84倍),对应的Bell参数为2.52,存储寿命达55。本工作为实现实用化量子中继及大规模量子网络的建设提供了可行的技术路线与关键的实验依据。

     

    Quantum interfaces that generate atom-photon (i.e., spin-wave-photon) entanglement are fundamental building blocks for quantum repeaters. Based on the Duan-Lukin-Cirac-Zoller (DLCZ) protocol in atomic ensembles, atom-photon entanglement can be probabilistically generated. The generation rate of entangled pairs is a core parameter that directly impacts the efficiency of quantum repeaters and quantum communication networks. Recent research on quantum repeaters has shown that temporal, spatial, and spectral multiplexing of quantum memories can effectively improve the entanglement generation rate. In this work, we develop a high-rate scalable six-channel temporal-multiplexed entanglement source via substantially increasing the experimental repetition rate and adopting a scalable pulsed-light fabrication technique. On the one hand, we shorten the experimental cycle to increase the repetition rate by optimizing the response time of the acousto-optic modulator (AOM), precisely controlling the pulse width and interval, and reducing signal transmission delays. Specifically, the AOM response time is reduced to 500 ns, the pulse width to 70 ns, and the pulse interval to 200 ns. On the other hand, we integrate an AOM network with a beam shaping device to realize accurate manipulation of the write pulse train. This structural design improves system compactness, spatial utilization, and stability, facilitating expansion to more time modes. Experimental results demonstrate that compared with conventional single-mode and nonmultiplexed entanglement sources, the generation rates of photon-atom entanglement (entangled photon pairs) are enhanced by factors of 4.42 (4.56) and 5.95 (5.84), respectively. The measured Bell parameter is 2.52, and the storage lifetime reaches 55 μs. The proposed scheme is cost-effective, highly compatible, and easy to operate. On this basis, further operations such as increasing the number of time modes, suppressing background noise, and implementing multimode multiplexing can be carried out. This work provides effective technical pathways and key experimental support for the construction of practical quantum repeaters and large-scale quantum networks.

     

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