Biased decoy-state reference-frame-independent quantum key distribution

Reference-frame-independent quantum key distribution (RFI-QKD) can generate secure keys even when the reference frames drift slowly. Here, we propose a new scheme on the decoy-state RFI-QKD, where the basis assignments of two legitimate parties are biased, reducing the fraction of mismatched-basis data. Considering statistical fluctuations under different misalignments of reference frames, we originally investigate the performance of biased decoy-state RFI-QKD with full parameter optimization. We also make a clear comparison between the new scheme with other practical schemes, e.g., unbiased decoy-state RFI-QKD and biased decoy-state BB84-QKD. Simulation results demonstrate that, the new proposed biased decoy-state RFI-QKD can significantly improve the performance (secret key rate and secure transmission distance), which shows great potential in real-life QKD systems. Graphical abstract: .