Rayleigh-Backscattering-Suppressed Two-Way Quantum Key Distribution

This paper reports, a detailed experimental study of the Rayleigh backscattering eects on single-mode bers (SMFs) fabricated by dierent vendors and on the quantum eciencies of an InGaAs/InP single-photon avalanche detector (SPAD). An optimization process for the input laser power to achieve negligible backscattering-induced error in a plug-and-play type two-way quantum key distribution (QKD) scheme was determined for a SMF transmission of 25 km. Based on this process, we have demonstrated 2 kbit/s quantum interference counts with 1-MHz optical pulses transmitted over the 25-km SMF, which allows a 1-kbit/s raw quantum key generation based on the BB84 protocol to be enabled. The measured QBER was less than 3 %. KCI Citation Count: 7