Effect of Intensity Modulator Extinction on Practical Quantum Key Distribution System

TL;DR

This paper analyzes how the imperfection of intensity modulators, specifically their extinction ratio, impacts the security and key rate of practical quantum key distribution systems.

Contribution

It introduces a security analysis considering the extinction ratio of intensity modulators and demonstrates that the secret key rate can be increased under certain practical assumptions.

Findings

Secret key rate increases with better extinction ratios.

Imperfections in intensity modulators affect QKD security.

Noise from imperfect modulators cannot be exploited by eavesdroppers.

Abstract

We study how the imperfection of intensity modulator effects on the security of a practical quantum key distribution system. The extinction ratio of the realistic intensity modulator is considered in our security analysis. We show that the secret key rate increases, under the practical assumption that the indeterminable noise introduced by the imperfect intensity modulator can not be controlled by the eavesdropper.