Practical continuous-variable quantum key distribution with feasible optimization parameters  

作　　者：Li MA Jie YANG Tao ZHANG Yun SHAO Jinlu LIU Yujie LUO Heng WANG Wei HUANG Fan FAN Chuang ZHOU Liangliang ZHANG Shuai ZHANG Yichen ZHANG Yang LI Bingjie XU 

机构地区：[1]Science and Technology on Communication Security Laboratory,Institute of Southwestern Communication,Chengdu 610041,China [2]State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications,Beijing 100876,China

出　　处：《Science China(Information Sciences)》2023年第8期76-87,共12页中国科学（信息科学）（英文版）

基　　金：supported in part by National Key Research and Development Program of China(Grant No.2020YFA0309704);National Natural Science Foundation of China(Grant Nos.U19A2076,62101516,62171418,62201530);Sichuan Science and Technology Program(Grant Nos.2022ZYD0118,2022YFG0330,2022ZDZX0009);Basic Research Program of China(Grant No.JCKY2021210B059);Chengdu Key Research and Development Support Program(Grant No.2021-YF05-02430-GX)。

摘　　要：Continuous-variable quantum key distribution(CV-QKD)offers an approach to achieve a potential high secret key rate(SKR)in metropolitan areas.There are several challenges in developing a practical CV-QKD system from the laboratory to the real world.One of the most significant points is that it is really hard to adapt different practical optical fiber conditions for CV-QKD systems with unified hardware.Thus,how to improve the performance of practical CV-QKD systems in the field without modification of the hardware is very important.Here,a systematic optimization method,combining the modulation variance and error correction matrix optimization,is proposed to improve the performance of a practical CV-QKD system with a restricted capacity of postprocessing.The effect of restricted postprocessing capacity on the SKR is modeled as a nonlinear programming problem with modulation variance as an optimization parameter,and the selection of an optimal error correction matrix is studied under the same scheme.The results show that the SKR of a CV-QKD system can be improved by 24%and 200%compared with previous frequently used optimization methods theoretically with a transmission distance of 50 km.Furthermore,the experimental results verify the feasibility and robustness of the proposed method,where the achieved optimal SKR achieved practically deviates<1.6%from the theoretical optimal value.Our results pave the way to deploy high-performance CV-QKD in the real world.

关 键 词：continuous-variable quantum key distribution POST-PROCESSING optimization secret key rate 

分 类 号：O413[理学—理论物理] TN918.4[理学—物理]