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arXiv · 2512.05496

Frequency-matching quantum key distribution

Hao-Tao Zhu·Yizhi Huang·Abdullah Rasmita·Chao Ding·Xiangbin Cai·Haoran Zhang·Xiongfeng Ma·Weibo Gao
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Abstract

Quantum key distribution (QKD) enables information-theoretically secure communication against eavesdropping. However, phase instability remains a challenge across many QKD applications, particularly in schemes such as twin-field QKD and measurement-device-independent QKD. The most dominant source of phase fluctuation arises from the frequency offset between independent lasers. Here we propose a method to address this issue by employing a classical photodiode to compensate for the laser frequency difference. As an application of this method, we implement this technique in a mode-pairing QKD system, achieving an error rate approaching the theoretical limit and surpassing the linear key-rate bound over a fiber distance of 296.8 km. This approach provides a practical solution for frequency matching between independent lasers and can be extended to other fields requiring precise phase stabilization.

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Hao-Tao Zhu, Yizhi Huang, Abdullah Rasmita, Chao Ding, Xiangbin Cai, Haoran Zhang, Xiongfeng Ma, Weibo Gao. 2025-12-05. Frequency-matching quantum key distribution. https://arxiv.org/abs/2512.05496

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