近日，中国科学技术大学徐飞虎团队探讨了量子密钥分配中时变侧信道的实验研究。相关论文于2025年4月28日发表在《物理评论A》杂志上。

量子密钥分发（QKD）允许远程各方共享经过验证的安全密钥。在实际应用中，基于法拉第镜和Sagnac环的光学方案被广泛应用于QKD系统中，以提高QKD系统的稳定性。在这些方案中，光在光路中双向传输，自动补偿环境造成的影响。然而，由于光源的有限消光比，这些方案将调制信号脉冲之间的泄漏光，从而产生随时间变化的侧通道。 

研究组对具有时变侧信道的实际量子密钥分发的安全性进行了全面的实验研究。他们使用法拉第镜和Sagnac环路在高速QKD系统中演示了编码模块的信息泄漏量。基于实验结果，研究组分析了安全风险和相应的对策。

附：英文原文

Title: Experimental study of time-dependent side channels in quantum key distribution

Author: Hao Tan, Weiyang Zhang, Liying Han, Sheng-Kai Liao, Feihu Xu

Issue&Volume: 2025/04/28

Abstract: Quantum key distribution (QKD) allows remote parties to share secret keys with proven security. In practice, optical schemes based on the Faraday mirror and Sagnac loop are widely used in QKD systems to improve the stability of QKD systems. In these schemes, light transmits bidirectionally in the optical path, compensating the effects caused by the environment automatically. However, due to the finite extinction ratio of the light source, these schemes will modulate the leaked light between the signal pulses, resulting in time-dependent side channels. Here, we provide a comprehensive experimental study of the security for practical QKD with time-dependent side channels. We demonstrate the amount of information leakage from the encoding modules using a Faraday mirror and Sagnac loop in a high-speed QKD system. Based on experimental results, we analyze the security risks and the corresponding countermeasures.

DOI: 10.1103/PhysRevA.111.042622

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.042622