Experimental Mode-Pairing Quantum Key Distribution Surpassing the Repeaterless Bound

IF 11.6 1区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Physical Review X Pub Date : 2025-05-02 DOI:10.1103/physrevx.15.021037

Likang Zhang, Wei Li, Jiawei Pan, Yichen Lu, Wenwen Li, Zheng-Ping Li, Yizhi Huang, Xiongfeng Ma, Feihu Xu, Jian-Wei Pan

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引用次数: 0

Abstract

Quantum key distribution (QKD) provides information-theoretic security for communication. The mode-pairing (MP) protocol emerges as a promising solution for long-distance QKD by eliminating the need for a global phase reference while maintaining the repeaterlike rate-loss scaling. Recent implementations have demonstrated its potential, but they either rely on costly ultrastable lasers or struggle with phase fluctuations from commercial lasers, particularly over long distances. As a result, surpassing the repeaterless bound with a practical system remains a challenge. In this work, we demonstrate a practical high-performance MP-QKD system using commercial lasers. To address phase fluctuations, we propose a frequency-tracking scheme based on fast Fourier transformation, enabling us to extend the pairing length to 2×105 pulses (160 μs). We propose a model to carefully analyze the phase noise and optimize the system parameters. Our system achieves an optimal secret key rate of 47.8 bit/s over 403 km of standard fiber (76.5 dB loss), exceeding the repeaterless bound by a factor of 2.92. Furthermore, we compare MP-QKD and twin-field QKD under various practical conditions and clarify the distinct application scenarios of the two protocols. These results confirm the feasibility of MP-QKD using cost-effective commercial technologies, paving the way for scalable quantum communication networks.

Published by the American Physical Society

2025

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超越无中继器边界的实验模式配对量子密钥分配

量子密钥分发（QKD）为通信提供了信息理论上的安全性。模式配对（MP）协议消除了对全局相位参考的需求，同时保持了类似中继器的速率损失缩放，成为长距离QKD的一种有前途的解决方案。最近的实现已经证明了它的潜力，但它们要么依赖于昂贵的超稳定激光器，要么与商业激光器的相位波动作斗争，特别是在长距离上。因此，在实际系统中超越无重复的界限仍然是一个挑战。在这项工作中，我们展示了一个实用的高性能MP-QKD系统，使用商用激光器。为了解决相位波动问题，我们提出了一种基于快速傅立叶变换的频率跟踪方案，使我们能够将配对长度扩展到2×105脉冲（160 μs）。我们提出了一个模型来仔细分析相位噪声并优化系统参数。我们的系统在403公里的标准光纤中实现了47.8比特/秒的最佳密钥速率（76.5 dB损耗），比无中继器边界高出2.92倍。此外，我们还比较了MP-QKD和双域QKD在各种实际条件下的性能，明确了两种协议的不同应用场景。这些结果证实了MP-QKD使用具有成本效益的商业技术的可行性，为可扩展的量子通信网络铺平了道路。2025年由美国物理学会出版

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Physical Review X PHYSICS, MULTIDISCIPLINARY-

CiteScore

24.60

自引率

1.60%

发文量

197

审稿时长

3 months

期刊介绍： Physical Review X (PRX) stands as an exclusively online, fully open-access journal, emphasizing innovation, quality, and enduring impact in the scientific content it disseminates. Devoted to showcasing a curated selection of papers from pure, applied, and interdisciplinary physics, PRX aims to feature work with the potential to shape current and future research while leaving a lasting and profound impact in their respective fields. Encompassing the entire spectrum of physics subject areas, PRX places a special focus on groundbreaking interdisciplinary research with broad-reaching influence.