Numerical Security Analysis of Three-State Quantum Key Distribution Protocol with Realistic Devices

TL;DR

This paper provides a comprehensive security analysis of the three-state quantum key distribution protocol using realistic device models, demonstrating secure communication over distances up to 200 km through numerical simulations.

Contribution

We proved the security of the three-state QKD protocol with realistic devices by establishing a squashing model, enabling numerical key rate calculations.

Findings

Achieved secure communication over 200 km.

Established the squashing model for measurement settings.

Enabled numerical key rate computation for realistic devices.

Abstract

Quantum key distribution (QKD) is a secure communication method that utilizes the principles of quantum mechanics to establish secret keys. The central task in the study of QKD is to prove security in the presence of an eavesdropper with unlimited computational power. In this work, we successfully solve a long-standing open question of the security analysis for the three-state QKD protocol with realistic devices, i,e, the weak coherent state source. We prove the existence of the squashing model for the measurement settings in the three-state protocol. This enables the reduction of measurement dimensionality, allowing for key rate computations using the numerical approach. We conduct numerical simulations to evaluate the key rate performance. The simulation results show that we achieve a communication distance of up to 200 km.