相位调制量子密钥分配系统中低频振动相移的实时跟踪补偿

Real-time low-frequency vibration phase drift tracking and auto-compensation in phase-coded quantum key distribution system

环境变化引起的相位漂移是双Mach-Zehnder量子密钥分配系统中误码和不稳定性的主要来源.相位漂移由高频振动和低频振动两部分组成,大部分这类振动的影响采用隔振措施(如用泡沫、橡皮包垫隔音)可以消除,而周期为3±0.32min的低频振动依然存在.报道了对这种低频固有振动引起的相移进行实时跟踪和补偿的方法.实验表明,采用这种方法实验室内实现75km量子密钥分配和量子保密通信,在24h内能长期稳定运行,误码率低于6%.

Phase drift caused by environment is the main source of quantum bit error rate and instability in the double M-Z interferometer quantum key distribution （QKD） system. The phase drift consists of both high-frequency and low-frequency vibrations, the former, which is due to environment noise, is usually conducted via the atmosphere and can be isolated by technological measures （e. g. using foamed-plastics wrapping or rubber pillow ）, the latter comes from building-vibration, which vibrates slowly with a serious impact on M-Z interferometer, with a period of 3 ± 0.32 min （min level）. A novel real-time tracking and compensation method for phase drift caused by low-frequency vibration is proposed. With the improved scheme, the QKD system based on double M-Z interferometers can operate stably for 24 hours, and key exchange with an error below 6 % over 75 kilometers has been achieved in the lab.