Abstract

In a two-way type plug and play system of quantum cryptography (QC), there are no troublesome adjustments that need to be made over long distances, and also it is stable for many hours. However, it is widely known that Rayleigh backscattering has an adverse effect on the performance of a two-way QC system using single photon detection. The backscattered (BS) light has the same wavelength as signal light and is generated anywhere in a fiber, hence it cannot be decoupled by controlling the detection time or using optical filtering. The BS light increases the probability of false detection, thus it reduces the safety of QC.

© 2007 IEEE