A 1550nm single-photon detector for fiber-optic quantum cryptography

Abstract

Quantum cryptography is a technique that allows two remote parties to share a common secret key by encoding one bit of information on a single photon. To achieve long-distance transmission, it is necessary to operate the system at the 1550 nm wavelength at which optical fibers exhibit minimum transmission loss. The authors have developed a 1550 nm single-photon detector by employing a thermoelectrically cooled InGaAs avalanche photodiode. This paper describes the operation principle and characteristics of the detector and discusses its application to long-distance quantum key distribution.