Quantum Secrecy in Thermal States III

TL;DR

This paper extends quantum secrecy protocols using thermal states to scenarios where eavesdroppers control the source, enabling secure key exchange with minimal infrastructure changes by leveraging quantum correlations.

Contribution

It introduces a method for quantum secure key exchange in thermal states even when the source is compromised, expanding the applicability of quantum cryptography.

Findings

Security guaranteed by Hanbury Brown and Twiss correlations

Key exchange feasible within the spatial coherence length

Minimal infrastructure modifications needed

Abstract

In this paper we expanded the security of a central broadcast protocol using thermal states to the case in which the eavesdropper controls the source. Quantum secrecy in a continuous variable central broadcast scheme is guaranteed by the quantum correlations present in thermal states arising from the Hanbury Brown and Twiss effect. This work allows for a method of key exchange in which two parties can agree a key as long as both can detect the same source and they are within the spatial coherence length of the source. This is important because it allows quantum secure key exchange with only minimal changes to existing infrastructure.