Influence of single photon detector on performance of quantum key distribution system

The physical model for the influence of single photon detector on the performance of quantum key distribution (QKD) system is analyzed according to the principle of QKD system and the operation mode of single photon detector. The relationship between the parameters of the single photon detector and the performance of the QKD system is also given. Various kinds of QKD systems are compared to derive a universal formula, which can describe the influence of single photon detector on any QKD scheme. The result shows that less time-slots of the single photon detector in the scheme may help to improve the performance of the QKD system.