QUANTUM CRYPTOGRAPHY

摘要

In a method of communication using quantum cryptography, single-photon signals from a highly attenuated source are modulated and subsequently detected. In the step of detecting the modulated signal, the signal is split between two branches according to its encoded state. Signals corresponding to different encoded states are detected independently in the respective branches and the rate of detection of coincident signals is determined. This rate is compared with a threshold to detect the presence of an eavesdropper.