Intensity correlations in measurement-device-independent quantum key distribution

TL;DR

This paper develops a theoretical model to evaluate how intensity correlations from imperfect modulation affect the security and key generation efficiency of measurement-device-independent quantum key distribution systems.

Contribution

It introduces a quantitative model for assessing the impact of intensity correlations on MDI QKD security, extending the analysis to practical systems with measured correlations.

Findings

Practical MDI QKD systems struggle to generate keys under intensity correlations.

Theoretical boundary conditions for secure key generation are identified.

The model helps evaluate the security impact of intensity correlations in real systems.

Abstract

The intensity correlations due to imperfect modulation during the quantum-state preparation in a measurement-device-independent quantum key distribution (MDI QKD) system compromise its security performance. Therefore, it is crucial to assess the impact of intensity correlations on the practical security of MDI QKD systems. In this work, we propose a theoretical model that quantitatively analyzes the secure key rate of MDI QKD systems under intensity correlations. Furthermore, we apply the theoretical model to a practical MDI QKD system with measured intensity correlations, which shows that the system struggles to generate keys efficiently under this model. We also explore the boundary conditions of intensity correlations to generate secret keys. This study extends the security analysis of intensity correlations to MDI QKD protocols, providing a methodology to evaluate the practical security of MDI QKD systems.