A novel approach to reducing information leakage for quantum key distribution

TL;DR

This paper introduces a new method to reduce information leakage in quantum key distribution by accounting for the overlap between quantum and post-processing leakage, leading to improved secure key rates and transmission distances.

Contribution

The paper proposes a novel approach that considers the overlap in information leakage, reducing it and enhancing the performance of QKD protocols.

Findings

Improved secure key rate (SKR) in simulations.

Extended maximal transmission distance.

Applicable to decoy-BB84 and twin-field protocols.

Abstract

Quantum key distribution (QKD) is an important branch of quantum information science as it holds promise for unconditionally secure communication. For QKD research, a central issue is to improve the final secure key rate (SKR) and the maximal transmission distance. To address this issue, most works focused on reducing the information leakage of QKD. In this paper, we propose a novel approach to further reduce the information leakage by specially considering the overlap between the information leakage of quantum part and post-processing part. The overlap means that the information leakage of post-processing part caused solely by multi-photon pulses is considered twice in previous studies, i.e., both in quantum part and post-processing part. Since the information carried by multi-photon pulses has been considered as completely known by Eve through the photon-number-splitting attack in quantum part, there is no need to consider it in post-processing part repetitively during the SKR calculation. Therefore, our approach can theoretically reduce the information leakage of a QKD protocol. Based on this idea, we derive the formulas to calculate the amount of information leakage for decoy-BB84 and sending-or-not-sending twin-field protocols. Simulation results for these two typical protocols also demonstrate that our approach evidently improves the SKR as well as the maximal transmission distance under practical experimental parameters.