The twin-field quantum key distribution (TF-QKD) protocol has been studied widely to overcome the linear bound, and several variations of the TF-QKD protocol have been proposed to improve security and practicality. One variation called the phase-matching QKD (PM-QKD) protocol develops an optical-mode-based security; simultaneously, it has a quadratic improvement of key rate without either basis choice or phase locking. So far, the main research work of the PM-QKD protocol has focused on symmetric channels. However, it is quite common that the two channels have asymmetric transmittances in real life. In this paper, we discuss the effects of asymmetric channels on the PM-QKD protocol; to reach a much better performance and achieve a higher key rate, the intensity must be optimized to compensate for channel asymmetry. We also study the practical issues of finite-key effects and intensity fluctuations, which have significant effects on the key rate of PM-QKD.

中文翻译：

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来源不稳定的非对称相位匹配量子密钥分布的有限键分析

为了克服线性边界，已经对双场量子密钥分配（TF-QKD）协议进行了广泛的研究，并且提出了TF-QKD协议的几种变体以提高安全性和实用性。一种称为相位匹配QKD（PM-QKD）协议的变体开发了一种基于光模式的安全性。同时，它在没有基础选择或锁相的情况下，密钥率也有了二次改进。到目前为止，PM-QKD协议的主要研究工作集中在对称信道上。但是，这两个通道在现实生活中具有不对称的透射率是很常见的。在本文中，我们讨论了非对称信道对PM-QKD协议的影响。为了达到更好的性能并获得更高的密钥速率，必须优化强度以补偿信道的不对称性。