Secure use of a single single-photon detector in a QKD system

摘要

A method of using a single single-photon detector (SPD) in a quantum key distribution (QKD) system is described. The method includes modulating a phase of a quantum signal a first time at a first QKD station by applying a first phase modulation randomly selected from a set of four possible phase modulations. The method also includes modulating the phase of the quantum signal a second time. The second modulation involves applying a second phase modulation randomly selected from the same set of four possible phase modulations. The method is a modification of the BB84 protocol and represents a higher level of quantum security than either the BB84 or B92 protocols when using a QKD system with a single SPD.