Figure 2
The schematic setup of our new passive-decoy state MDI-QKD protocol.
Alice and Bob generate the passive HSPS as illustrated in Fig. 1, and randomly code each signal pulse into one of the four polarization states (horizontal (H), vertical (V), 45 degrees (+) and 135 degrees (−)) with a polarization rotator (PR). Then they simultaneously send their signal pulses to the third party (Charlie) through the quantum channel. Charlie apply a partial Bell-state projection measurement on pulses from both Alice and Bob. Ai (i = 1, 2, 3, 4): triggering single-photon detectors. Di (i = 1, 2, 3, 4): triggered single-photon detectors. PBS: polarization beam-splitter. BS: beam-splitter.
