Reference-Frame-Independent Mode-Pairing Quantum Key Distribution with Advantage Distillation

The coordination between distance and the secure key rate is one of the main challenges in the practical application of quantum key distribution (QKD). Mode-pairing quantum key distribution is one of the schemes that can surpass the secret key capacity for repeaterless QKD. However, the protocol utilizes phase to encode the information, which leads to the problem of active stabilization in the interferometer. In this paper, a reference-frame-independent mode-pairing quantum key distribution (RFI-MP-QKD) is proposed as an effective scheme to solve this problem. Moreover, the performance of the RFI-MP-QKD protocol is improved by applying the Advantage Distillation (AD) method in data post-processing, which separates the highly correlated raw key bits from the weakly correlated information. The simulation results show that the secure key rate of RFI-MP-QKD has almost no degradation for reference frame deviation angles of 0 degrees similar to 7 degrees. Compared to RFI-MP-QKD without AD method, the AD method decreases the quantum bit error rate from 0.04 to 0.012 and increases the maximum transmission distance from 406 to 450 km. The scheme proposed is expected to facilitate the practical implementation of RFI-MP-QKD, especially in cases of concerning reference frame alignment and high channel loss.