Security of quantum key distribution with passive basis choice and detection-efficiency mismatch for a realistic satellite setup

Detection-efficiency mismatch is a common problem in realistic quantum key distribution (QKD) systems. The existing security proofs for the case of the passive basis choice provide a nonzero secret key rate only for a small detection-efficiency mismatch. Unfortunately, in realistic setups, the detection-efficiency mismatch can be significant. Here we present a more precise estimation of the secret key rate for the BB84 protocol with the passive basis choice, which accounts for the detection-efficiency mismatch between four threshold detectors as well as an adaptation of the decoy-state method. The suggested approach is used to estimate the secret key rate in a QKD experiment between the Micius satellite and the Zvenigorod ground station.

Source: arXiv:2608.09793v1 - http://arxiv.org/abs/2608.09793v1 PDF: https://arxiv.org/pdf/2608.09793v1 Original Link: http://arxiv.org/abs/2608.09793v1