Improving the performance of practical reference-frame-independent quantum key distribution under the afterpulse effect

Reference-frame-independent quantum key distribution (RFI-QKD) can generate secure keys between two remote peers with an unknown and slowly drifted reference frame. As an intrinsic characteristic of single-photon avalanche detectors, the afterpulse effect is often ignored in the simulation of the analytical model, which leads to a large deviation from the data obtained in practical RFI-QKD systems. Therefore, an afterpulse-compatible model should be adopted to fix this deviation. However, the afterpulse-compatible model results in a decline in the performance of RFI-QKD systems. To mitigate the performance decline of RFI-QKD under the afterpulse effect, we apply the advantage distillation (AD) method to enhance the secret key rate and the maximum transmission distance. Simulation results demonstrate that, without changing the optical hardware of RFI-QKD systems, the AD method can substantially improve the performance of RFI-QKD under the afterpulse effect.