Security analysis method for practical quantum key distribution with arbitrary encoding schemes

TL;DR

This paper introduces a universal security analysis method for practical quantum key distribution systems that accommodates arbitrary encoding schemes and real-world imperfections, providing tighter security bounds.

Contribution

It presents a new, versatile security analysis approach based on statistical data correlations, applicable to various complex and realistic QKD implementations.

Findings

The method yields tighter security bounds than GLLP analysis.

It effectively analyzes source flaws and high-dimensional asymmetric protocols.

The approach enhances the security assessment of practical QKD systems.

Abstract

Quantum key distribution (QKD) gradually has become a crucial element of practical secure communication. In different scenarios, the security analysis of genuine QKD systems is complicated. A universal secret key rate calculation method, used for realistic factors such as multiple degrees of freedom encoding, asymmetric protocol structures, equipment flaws, environmental noise, and so on, is still lacking. Based on the correlations of statistical data, we propose a security analysis method without restriction on encoding schemes. This method makes a trade-off between applicability and accuracy, which can effectively analyze various existing QKD systems. We illustrate its ability by analyzing source flaws and a high-dimensional asymmetric protocol. Results imply that our method can give tighter bounds than the Gottesman-Lo-L\"utkenhaus-Preskill (GLLP) analysis and is beneficial to analyze protocols with complex encoding structures. Our work has the potential to become a reference standard for the security analysis of practical QKD.