METHOD AND APPARATUS FOR POLARISATION-INSENSITIVE QUANTUM CRYPTOGRAPHY

摘要

A communication system uses quantum cryptography for the secure distribution of a key. A single-photon signal is phase-modulated and transmitted over a pair of time-multiplexed transmission paths. With each original single-photo n signal in a given one of the transmission paths, a duplicate signal is transmitted. The duplicate is identically modulated and orthogonally polarised. At the receiver, the outputs of the two paths are combined interferometrically. A single polarisation-insensitive measurement is derive d from the combined contributions of the orthogonally polarised signals.