Abstract: Mode-pairing quantum key distribution (MP-QKD) offers advantages of low experimental technical complexity, robust security, and the ability to break the limit of secure key capacity, rendering it a subject of significant research interest and promising application potential. However, the key rate of MP-QKD is limited because of using the weak coherent source (WCS) as the signal light source, 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 (HPCS) is used as the signal light source in MP-QKD. Due to the higher proportion of single photons in HPCS, the performance of MP-QKD is significantly improved. The numerical simulation is carried out in the case of asymptotic and infinite decoy states, the result shows that the HPCS MP-QKD outperforms the WCS MP-QKD, achieving not only a higher key rate but also a longer communication distance. Moreover, HPCS MP-QKD demonstrates a more obvious advantage in terms of the key rate when the transmission distance exceeds 400 km.

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