Single-photon detector for long-distance fiber-optic quantum key distribution

We have investigated the performance of an InGaAs/InP avalanche photodiode for photon counting at 1550 nm in the temperature range of thermoelectric cooling. A quantum efficiency of 13.7% was obtained at -55 degreesC, while the dark-count probability per gate (similar or equal to 1 ns) was kept as small as 2.4 x 10(-5). The developed single-photon detector would yield a 104.4-km fiber-optic quantum key distribution in the ideal condition. (C) 2002 Optical Society of America.