Realistic Device Imperfections Affect the Performance of Hong-Ou-Mandel Interference With Weak Coherent States

Measurement-device-independent quantum key distribution (MDI QKD) is a promising and practical protocol for remote secret sharing, where the Hong-Ou-Mandel (HOM) type interference in the measurement side provides a simple and economic way to resist malicious attacks on the measurement devices. Because the HOM interference greatly indicates the performance of MDI QKD system, its interferential behavior in practical situations deserve to be studied. In this work, we analyzed HOM visibility with several practical imperfections, such as the deviation of the beam splitting ratio, detection efficiency mismatch of detectors, inconsistent intensities of two incident pulses. In particular, we discussed the afterpulse effect of InGaAs avalanche photodiode detectors with a non-Markovian model, where we take the avalanche history into consideration and provide a new and more accurate perspective for afterpulse analysis. Simulation results indicate that the afterpulse effect in practical situation has a greater impact on the HOM performance than other imperfections. The results exhibit its value in realistic high-speed MDI QKD systems as well as other fiber-based HOM applications.