Quantum key distribution with displaced thermal states

TL;DR

This paper demonstrates a practical microwave quantum key distribution protocol using displaced thermal states, leveraging common equipment and thermal noise for secure key sharing among multiple parties.

Contribution

It introduces a novel thermal state QKD protocol with displaced thermal states, simplifying implementation and utilizing readily available broadcasting equipment.

Findings

Successful experimental implementation in the microwave region

Shared thermal states enable key generation without specialized equipment

Thermal noise facilitates secure key recovery among parties

Abstract

Secret key exchange relies on the creation of correlated signals, serving as the raw resource for secure communication. Thermal states, exhibit Hanbury Brown and Twiss correlations, which offer a promising avenue for generating such signals. In this paper, we present an experimental implementation of a central broadcast thermal state quantum key distribution (QKD) protocol in the microwave region. Our objective is to showcase a straightforward method of QKD utilizing readily available broadcasting equipment. Unlike conventional approaches to thermal state QKD, we leverage displaced thermal states. These states enable us to share the output of a thermal source among Alice, Bob, and Eve via both waveguide channels and free space. Through measurement and conversion into bit strings, our protocol produces key-ready bit strings without the need for specialized equipment. By harnessing the inherent noise in thermal broadcasts, our setup facilitates the recovery of distinct bit strings by all parties involved.