Zong-Wen Yu

Channel loss is one of the most severe limitation to extend the transmission distance of quan- tum key distribution in practice. The twin-field quantum key distribution can achieve a much longer transmission distance with improving the key rate from the linear scale of channel loss in the traditional decoy-state method to the square root scale of the channel transmittance. Here we demonstrate the real-optical-fibre experimental results of twin-field quantum key distribution through the sending-or-not-sending protocol, which is fault tolerant to large misalignment error. The phase locking technology developed in the frequency transfer field is adopted to ensure Alice’s and Bob’s source wavelengths are locked to each other. Phase reference pulses are used to monitor the phase difference between the channel. Further with a high performance single photon detector, we obtain the positive key rates for different distances, specifically, the obtained secure key rate at 150 km is higher than that of the measurement device independent QKD.