Quantum cryptographic communication channel based on quantum coherence

摘要

A quantum cryptographic communication channel having: a light source; a reflector; first and second sources each capable of generating a pair of photons emitted in the form of signal and idler light beams when energized by the light source, the first and second sources being arranged relative to each other such that the idler beam from the first source is incident upon the second source and aligned into the idler beam of the second source and the signal beams are directed by the reflector to converge upon a common point; a light modulator for changing the phase of the idler beam from the first source between first and second phase settings before being incident upon the second source; a controller for controlling the timing of the phase change from the first phase setting to the second phase setting; first and second detectors for detecting the incidence of the signal beams from the first and second sources; and a beam splitter disposed at the common point for directing the signal beams to the first detector when the phase of the idler beam from the first source has the first phase setting and to the second detector when the phase of the idler beam from the first source has the second phase setting.