Afterpulse analysis for reference-frame-independent quantum key distribution.

Reference-frame-independent quantum key distribution (RFI-QKD) can generate secret keys without the alignment of reference frames. However, in most RFI-QKD systems, the afterpulse inherent in single-photon avalanche detectors at the receiver's side is always ignored, which will lead to a large deviation from the data obtained by the existing analytical models. In this paper, we establish an afterpulse-compatible analytical model to fix this deviation. Simulation results show that the secret key rate is overestimated when the afterpulse is ignored. Furthermore, based on the afterpulse-compatible model, we investigate the effect of the intensity fluctuation of the source at the transmitter's side. Simulation results show that both the afterpulse and the intensity fluctuation affect the secret key rate, which should be carefully considered in practical RFI-QKD systems. [ABSTRACT FROM AUTHOR]