Experimental asymmetric Plug-and-Play Measurement-device-independent   quantum key distribution
  Measurement-device-independent quantum key distribution (MDI-QKD) is immune to all security loopholes on detection. Previous experiments on MDI-QKD required spatially separated signal lasers and complicated stabilization systems. In this paper, we perform a proof-of-principle experimental demonstration of plug-and-play MDI-QKD over an asymmetric channel setting with a single signal laser, in which the whole system is automatically stabilized in spectrum, polarization, arrival time and phase reference. Both the signal laser and the single-photon detectors are in the possession of a common server. A passive timing calibration technique is applied to ensure the precise and stable overlap of signal pulses. The results pave the way for the realization of a quantum network, in which the users only need the encoding devices. 
Guang-Zhao Tang, Shi-Hai Sun, Feihu Xu, Huan Chen, Chun-Yan Li, and   Lin-Mei Liang
quant-ph