Critical side channel effects in random bit generation with multiple semiconductor lasers in a polarization-based quantum key distribution system

摘要

Most polarization-based BB84 quantum key distribution (QKD) systems utilizemultiple lasers to generate one of four polarization quantum states randomly.However, random bit generation with multiple lasers can potentially opencritical side channels, which significantly endangers the security of QKDsystems. In this paper, we show unnoticed side channels of temporal disparityand intensity fluctuation, which possibly exist in the operation of multiplesemiconductor laser diodes. Experimental results show that the side channelscan enormously degrade security performance of QKD systems. An important systemissue for the improvement of quantum bit error rate (QBER) related with laserdriving condition is furtherly addressed with experimental results.