Field experimental mode-pairing quantum key distribution with intensity fluctuations.

The mode-pairing quantum key distribution (MP-QKD) protocol, which can achieve high key rates over long distances without phase locking, is a potential candidate for implementing intercity QKD. However, achieving precise control of the light source intensity in a field MP-QKD experiment is an exceedingly challenging task. In this Letter, we study the decoy-state MP-QKD protocol with light source intensity fluctuations. Furthermore, we propose a statistical analysis method based on the T-distribution to calculate confidence intervals of intensity fluctuations. Finally, in the field MP-QKD experiments, considering intensity fluctuations and the finite size effect, we obtain secure key rates of 1.03 × 10 bit/pair and 3.64 × 10 bit/pair for the symmetric (195.8 km) and asymmetric (127.7 km) cases, respectively.