在相位编码量子密钥分发系统中, 单光子干涉可视度决定了系统的成码率。本文提出一种优化单光子干涉可视度的方法, 即利用遗传算法和四通道偏振控制器实时补偿单光子偏振漂移, 同时利用时分复用参考光连续无复位地补偿单光子相位漂移, 最终在25 km光纤中实时优化的单光子干涉可视度达到98.6%, 相位编码量子密钥分发系统成码率为2.2 kbit/s。

For the phase coding quantum key distribution system,the single photons interference visibility determines the system key rate. We have presented a robust method of real-time optimization for single photons interference visibility. The single photons polarization drift is compensated based on the genetic algorithm using the four-channel polarization controller,and the phase drift is calibrated continuously using the digital phase shifter with the time-multiplexed reference pulses. Finally in the 25 km fiber,the optimized single photons interference visibility reaches to 98.6% and the system key rate is 2.2 kbit/s.