Plug-and-Play Measurement-Device-Independent Quantum Key Distribution

Quantum key distribution (QKD) gaurantees unconditional communication security based on the laws of quantum physics. However, practical QKD suffers from a number of quantum hackings due to the device imperfections. From the security standpoint, measurement-device-independent quantum key distribution (MDI-QKD) is in the limelight since it eliminates all the possible loopholes in detection. Due to active control units for mode matching between the photons from remote parties, however, the implementation of MDI-QKD is highly impractical. In this article, we propose a novel method in which the indistinguishability issue is resolved without any active control unit. By introducing Plug-and-Play (P&P) concept into MDI-QKD, the indistinguishability between photons can naturally be guaranteed. We show the feasibility of P&P MDI-QKD with a proof-of-principle experiment.