Gaussian one-way thermal quantum cryptography with finite-size effects

TL;DR

This paper analyzes how finite-size effects influence the security of thermal one-way quantum cryptography, providing key rate calculations and security thresholds across frequencies, highlighting performance degradation.

Contribution

It introduces a detailed finite-size analysis for thermal quantum cryptography using coherent and squeezed states with added thermal noise, advancing security assessment methods.

Findings

Finite-size effects reduce the achievable key rate.

Security thresholds vary with transmission frequency.

Performance degradation quantifies the impact of finite-size effects.

Abstract

We study the impact of finite-size effects on the security of thermal one-way quantum cryptography. Our approach considers coherent/squeezed states at the preparation stage, on the top of which the sender adds trusted thermal noise. We compute the key rate incorporating finite-size effects, and we obtain the security threshold at different frequencies. As expected finite-size effects deteriorate the performance of thermal quantum cryptography. Our analysis is useful to quantify the impact of this degradation on relevant parameters like tolerable attenuation, transmission frequencies at which one can achieve security.