连续变量量子密钥分发系统调制方差全局优化方法研究

Global Optimization of Modulation Variance for Continuous Variables Quantum Key Distribution System

连续变量量子密钥分发技术具有与传统光通信网络兼容性好、安全码率高等优点.调制方差是连续变量量子密钥分发协议的关键参数,其优化选取将直接影响系统安全码率和传输距离.本文针对确定的数据协商和纠错译码算法,量化分析了实际连续变量量子密钥分发系统中调制方差对误帧率、协调效率等参数的影响,以此为基础给出了一种连续变量量子密钥分发协议调制方差全局优化方法,以达到安全码率最大化效果.相较于已知常用方法,本优化方法在典型连续变量量子密钥分发系统参数下,仅通过调制方差参数优化即可显著提升安全码率,而无需做复杂硬件优化,可行性好且效果佳.此外,该方法适用于各类连续变量量子密钥分发协议,包括高斯调制、离散调制协议等,也适用于有限码长和无限码长情形,可扩展性好.

Continuous variable quantum key distribution technology has the advantages of good compatibility with traditional optical communication network and high secret key rate.In a practical implementation of a continuous variable quantum key distribution system,the modulation variance is a key parameter which directly affects the secret key rate and transmission distance of the system.In this paper,a novel optimization scheme for the modulation variance of the continuous variable quantum key distribution system is proposed to maximize the secret key rate.It quantitatively analyzes the influence of the modulation variance on the frame error rate and reconciliation efficiency.Compared with the previous known optimization methods,the scheme proposed in this paper can significantly improve the secret key rate with typical system parameters,which is achieved by purely optimizing the modulation variance without any hardware change.In addition,the scheme proposed in this paper is extensible and can be applied in various continuous variable quantum key distribution protocols,including the Gaussian modulation protocol and the discrete modulation protocol.