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

TL;DR

This paper introduces a biased decoy-state reference-frame-independent quantum key distribution scheme that enhances key rate and transmission distance by reducing mismatched data, even with reference frame drift.

Contribution

It proposes a novel biased basis assignment method for decoy-state RFI-QKD, improving performance over existing schemes under practical conditions.

Findings

Significant increase in secret key rate

Extended secure transmission distance

Better performance compared to unbiased schemes

Abstract

Without actively aligning the reference frames, the 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. When accounting for statistical fluctuations under different misalignments of reference frames, we 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) of practical QKD systems.