Hacking the subcarrier wave quantum key distribution system by exploiting the avalanche-transition region of a single-photon detector

This paper investigates loopholes in subcarrier wave quantum key distribution systems associated with the superlinear operating regime of avalanche photodiode single-photon detectors. The results demonstrate that an eavesdropper can control the receiver’s detection outcomes. The presented analysis may facilitate the identification of similar attacks and the development of countermeasures for quantum key distribution systems.