Perceiving Quantum Hacking For Quantum Key Distribution Using Temporal

Quantum key distribution (QKD) can generate secure key bits between remote users with quantum mechanics. However, the gap between the theoretical model and practical realizations gives eavesdroppers opportunities to intercept the secret key. The most insidious attacks, known as quantum hacking, are the ones with no significant discrepancy of the measurement results using side-channel loopholes of QKD systems. Depicting full-time-scale characteristics of the quantum signals, the quantum channel, and the QKD system can provide legitimate users extra capabilities to defeat malicious attacks. Here, we propose the method exploring a temporal ghost-imaging (TGI) scheme to perceive quantum hacking with temporal fingerprints and experimentally verify its validity. The scheme presents a common approach to promote QKD's practical security from a unique perspective of signals and systems.