Rigorous phase-error-estimation security framework for QKD with correlated sources

TL;DR

This paper presents a rigorous security framework for quantum key distribution (QKD) that accounts for correlations in practical sources, bridging the gap between theory and real-world implementations.

Contribution

It introduces a mathematical framework extending phase-error-estimation security proofs to correlated sources, enhancing the rigor and generality of QKD security analysis.

Findings

Framework effectively models correlated sources in QKD.

Significantly improves security guarantees for practical QKD systems.

Addresses limitations of previous security proof methods.

Abstract

Practical QKD modulators introduce correlations between consecutively emitted pulses due to bandwidth limitations, violating key assumptions underlying many security proof techniques. Here, we address this problem by introducing a simple yet powerful mathematical framework to directly extend phase-error-estimation-based security proofs for imperfect but uncorrelated sources to also incorporate encoding correlations. Our framework overcomes important limitations of previous approaches in terms of generality and rigor, significantly narrowing the gap between theoretical security guarantees and real-world QKD implementations.