Improving key rates by tighter information reconciliation leakage estimation for quantum key distribution

TL;DR

This paper introduces a new method for estimating information leakage in quantum key distribution, leading to more accurate key rate calculations and extended transmission distances.

Contribution

It presents a novel approach that accounts for quantum effects in post-processing, improving leakage estimation and enhancing secure key rates in QKD protocols.

Findings

More accurate estimation of information leakage improves SKR.

Significant increase in maximum transmission distance for QKD protocols.

Simulation results confirm theoretical improvements.

Abstract

Previous research has aimed to precisely estimate information leakage to improve the secure key rate (SKR) and maximum transmission distance in quantum key distribution (QKD). However, existing methods repeatedly considerd the information of the multi-photon pulses known to Eve before and after information reconciliation, resulting in an overestimation of the leakage amount. We propose a novel approach that considers the quantum part's effect on post-processing, providing a more accurate estimation of information reconciliation leakage to improve the SKR. Theoretical analysis shows that our method more accurately estimates the information reconciliation leakage, significantly improving the SKR at any distance as well as the maximum transmission distance. It is worth mentioning that previous studies treat information leakage of the error correction as Shannon bound $Nh(e)$, and our method can estimate it more tightly. Simulation results for decoy-BB84 and measurement-device-independent (MDI) protocols using Cascade are consistent with the theoretical analysis. The farther the transmission distance, the greater the growth rate of SKR. When the error rate is 33%, compared with the original method, the SKR growth rate of decoy-BB84 at 100KM is 100.4%, and the transmission distance of MDI increases by 22KM.