We have implemented a differential-phase-shift (DPS) quantum key distribution (QKD) system at 1310 nm with superconducting single photon detectors (SSPD). The timing jitter of the SSPDs is small and its dark counts are very low. 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%.
Citation: New Journal of Physics
Pub Type: Journals
differential phase shift, optical fiber communication, quantum key distribution, superconducting single photon detector