Quantum secrecy in thermal states

Abstract

We propose to perform quantum key distribution using quantum correlations occurring within thermal states produced by low power sources such as LEDs. These correlations are exploited through the Hanbury Brown and Twiss effect. We build an optical central broadcast protocol using a superluminescent diode which allows switching between laser and thermal regimes, enabling us to provide comparable experimental key rates in both regimes. We provide a theoretical analysis and show that quantum secrecy is possible, even in high noise situations.