Abstract: The key rate of mode-pairing quantum key distribution is limited because of using weak coherent sources as signal light sources, characterized by a limited single photon component. To address this problem, mode-pairing quantum key distribution based on heralded pair-coherent source is proposed, the heralded pair-coherent source is used as the signal light source in mode-pairing quantum key distribution. Due to the higher proportion of single photons in the heralded pair-coherent source, the performance of mode-pairing quantum key distribution is significantly improved. The numerical simulation is carried out in the cases of asymptotic and infinite decoy states. The result shows that the proposed protocol outperforms the mode-pairing quantum key distribution based on the weak coherent source, achieving not only a higher key rate but also a longer communication distance. The proposed protocol demonstrates a significant advantage in terms of the key rate when the transmission distance exceeds 400 km.

Key words: quantum key distribution, mode-pairing quantum key distribution, heralded pair-coherent source, secure key rate