1310 nm differential-phase-shift QKD system using superconducting single-photon detectors
Lijun Ma, Sae Woo Nam, Hai Peng Xu, Burm Baek, Tiejun Chang, Oliver Slattery, Alan Mink, Xiao Hong Tang · New Journal of Physics · 2009
We have implemented a differential-phase-shift (DPS) quantum key distribution (QKD) system at 1310 nm with superconducting single-photon detectors (SSPDs). The timing jitter of the SSPDs is very small (∼60 ps) and their dark counts rate is low (<200 s −1 ). 1310 nm is an ideal quantum signal wavelength for a QKD system, where quantum signals coexist with classical communication signals at 1550 nm in one fiber. As the key element in the DPS QKD, a Michelson interferometer was designed and built using Faraday mirrors that can automatically compensate for the polarization evolution in the fiber. As the result, our DPS QKD system can be steadily operated at 2.5 GHz clock rate with a low quantum error rate of less than 4%.