Quantum secure direct communication based on fully passive source

TL;DR

This paper introduces a passively-sourced quantum secure direct communication protocol that enhances security against side-channel attacks by avoiding active modulation, achieving near comparable transmission distances to traditional methods.

Contribution

The authors propose a fully passive source-based QSDC protocol that improves security and robustness by eliminating active modulation at the source.

Findings

Achieves maximum secrecy message rates of 5.76e-5, 9.92e-6, 4.99e-7 bits/sec at 5, 10, 15 km.

Maximum communication distance is approximately 16.875 km, about 94.4% of active modulation protocols.

System model and parameter optimization demonstrate the protocol's effectiveness.

Abstract

In practical quantum communication, imperfect devices may introduce side channels, creating opportunities for eavesdroppers. Especially on the source side, the side channels created by active modulation may compromise the security of the protocol. We proposes a passively-sourced quantum secure direct communication (QSDC) protocol based on fully passive source. By passively modulating both the quantum state and the intensity of the decoy state, we can avoid active modulation operations at the source, thereby enhancing the robustness of QSDC against side-channel attacks. We developed a system model and conducted parameter optimization to obtain the maximum secrecy message transmission rate achievable by the protocol for each channel attenuation. At a channel attenuation of 2, 4, 6 dB (corresponding to a communication distance of 5, 10, 15 km), the secrecy message transmission rates are 5.76 * 10^-5, 9.92 * 10^-6, and 4.99 * 10^-7 bit/sec. And its maximum communication distance is about 16.875 km, which is about 94.4% of that of actively modulated QSDC.