摘要
连续变量量子密钥分发系统中,本地光场和信号光场采用时分复用,偏振复用方式通过长距离单模光纤传输.外界复杂环境会使单模光纤产生双折射效应,导致本地光场和信号光场的偏振态漂移,严重影响接收端平衡零拍探测结果.因此,高效动态偏振控制单元是推动系统外场实用化进程的关键技术.本文理论上证明了系统接收端仅考虑任意偏振消光比输出时,偏振控制单元只需两个控制自由度即可.在此基础上将贝叶斯参数估计方法有效融入混沌-猴群算法,同时在现场可编程逻辑门阵列硬件上实现控制算法,结合积分型光场探测器建立动态偏振控制单元,仿真和实验结果表明单次偏振控制静态消光比达到30 dB以上的平均周期为400μs.为了应对偏振态连续变化情况,将动态偏振控制单元集成到连续变量量子密钥分发系统,实验测试了偏振态扰动速率在0—2 krad/s范围内系统仍然能够正常运转.
In a commercial fiber-based quantum key distribution system,the local and signal optical fields are transmitted through long distance fibers by using time division multiplexing and polarization multiplexing.The state of polarization of the optical field is inevitably disturbed by random birefringence of the standard singlemode fiber caused by external complex environments.This drift of the state of polarization significantly affects the balanced homodyne detection results and the secret key rate.Therefore,the key technology of the dynamic polarization control unit is crucial for the system in a large-scale commercial application.We theoretically analyze and prove that the polarization control unit only needs the combination of two degrees of freedom when considering the result of an arbitrary polarization extinction ratio at the receiver of the system.To overcome the influence of polarization variations,we propose a chaotic monkey algorithm based on Bayesian parameter estimation method and implement intelligence algorithm on field programmable gate array(FPGA)hardware under pulsed light with an integral-type detector for the dynamic polarization control unit.The simulation results show that the optimal combination is four degrees of freedom and the optimal prior distribution is an exponential distribution among various distributions in the dynamic polarization control unit.According to the simulation results,the experimental results show that the achieved polarization extinction ratio is over 30 dB and the average time of polarization control is 400μs for a single random polarization scrambling.By combining the dynamic polarization control unit with the system,we demonstrate the continuous variable quantum key distribution(CV-QKD)under a continuous polarization scrambling scope of 0-2 krad/s and verify its effectiveness.In addition,the methods presented will improve the performance of the system and expand the range of applications even under strong external disturbance.
作者
张光伟
白建东
颉琦
靳晶晶
张永梅
刘文元
Zhang Guang-Wei;Bai Jian-Dong;Jie Qi;Jin Jing-Jing;Zhang Yong-Mei;Liu Wen-Yuan(Department of Physics,School of Semiconductor and Physics,North University of China,Taiyuan 030051,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第6期119-127,共9页
Acta Physica Sinica
基金
国家自然科学基金(批准号:12104419,12104417,12104418)
山西省基础研究计划(批准号:20210302124689,20210302124161,20210302124025)资助的课题。
关键词
连续变量量子密钥分发
贝叶斯参数估计方法
猴群算法
动态偏振控制器
continuous variable quantum key distribution
Bayesian parameter estimation method
monkey algorithm
dynamic polarization controller
