Practical security analysis of continuous-variable quantum key distribution with an unbalanced heterodyne detector  

作　　者：Lingzhi Kong Weiqi Liu Fan Jing Chen He 孔令志;刘维琪;荆凡;贺晨(College of Information Science and Technology,Northwest University,Xi’an 710127,China)

机构地区：[1]College of Information Science and Technology,Northwest University,Xi’an 710127,China

出　　处：《Chinese Physics B》2022年第7期119-126,共8页中国物理B（英文版）

基　　金：the National Natural Science Foundation of China(Grant No.62001383);the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2019JM-591)。

摘　　要：When developing a practical continuous-variable quantum key distribution(CVQKD),the detector is necessary at the receiver's side.We investigate the practical security of the CVQKD system with an unbalanced heterodyne detector.The results show that unbalanced heterodyne detector introduces extra excess noise into the system and decreases the lower bound of the secret key rate without awareness of the legitimate communicators,which leaves loopholes for Eve to attack the system.In addition,we find that the secret key rate decreases more severely with the increase in the degree of imbalance and the excess noise induced by the imbalance is proportional to the intensity of the local oscillator(LO)under the same degree of imbalance.Finally,a countermeasure is proposed to resist these kinds of effects.

关 键 词：continuous-variable quantum key distribution heterodyne detector 

分 类 号：O413[理学—理论物理] TN918.4[理学—物理]