诱惑态量子密钥分配系统中统计涨落的研究

Analysis of statistical fluctuation in decoy state quantum key distribution system

针对实用的量子密钥分配(QKD)系统是基于强衰减的弱激光脉冲作为单光子源,光子数分束攻击极大限制了通信双方在非理想条件下QKD的传输距离和密钥生成率,采用大数定律对诱惑态协议中单光子的计数率、单光子增益和误码率分别进行统计涨落分析,利用双诱惑态比较了1310 mn和1550 nm条件下,编码脉冲的长度为(N=10°-N=10^(12))实际QKD协议中密钥的生成率与安全传输距离之间的关系、安全传输距离随编码长度的变化的关系,得出脉冲编码长度增大到N=10^(12)时,密钥的最大安全传输距离为135 km.

Decoy state has proven to be a very useful method of significantly enhancing the performance of a quantum key distribution （QKD） system with practical light sources. The data-set size in practical QKD protocol is always finite, which will cause statistical fluctuations. The gain and the error rate of the quantum state are analyzed by considering absolutely statistical fluctuation. The relation between key generation rate and the secure communication distance is shown with exchanged quantum signal （N = 106 - 1012） by the method of two-decoy-state protocol under the condition that communication wavelength is 1310 nm （or1550 nm）. The result indicates that the minimal number of exchanged quantum signals increases obviously with the increase of transmission distance. The secure transmission distance is 135 km under the condition that quantum signal is 1012.