The Secure Transmission Criterion of Practical Polarization CodingQKD Systems under PNS Attacks

摘要

After over twenty years since the demonstration of the first QKD systems in 1989 there have been two categories ofQKD systems, namely fiber QKD systems and wireless QKD systems. The security of a practical QKD system overwireless optical paths is degraded due to imperfectness of devices and channel loss. Very simple attacks, such as beam-splitting attacks (BS), could jeopardize the security of polarization coding QKD systems. Among all the attacks photonnumber splitting (PNS) is the most threatening one against the security of polarization coding QKD systems. The upperbound for secure transmission length of free-space QKD systems based on polarization coding under PNS attacks isprovided here as well as the secure transmission criterion. The theoretic results predicted in this paper accord withexperimental results of Manderbach's work.