WATCH DOG DETECTOR FOR QKD SYSTEM

摘要

A single-photon "watch dog" detector (286) for a two-way quantum key distribution (QKD) system (200) is described. By counting the number of weak pulses (e.g., P1, P2) entering and/or leaving the reflecting QKD station (Alice), an eavesdropper (Eve) that attempts to add weak pulses (P3) to the quantum channel (240) in order to gain phase information from the phase modulator (266) at Alice in order to deduce information about the key being exchanged can be detected.