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

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... is possible, even in high noise situations. Prelude In 2016, China launched what Gibney dubbed the first quantum satellite [1], the intent of which is to perform quantum key distribution between the satellite and ground stations, see for instance [2] . This is just one of the current practical schemes designed to perform quantum secure key distribution and communication between parties; other examples include the DARPA network [3], the SECOQC project [4], or the Durban-QuantumCity project [5, 6], which use fibre-optic technologies to build quantum networks. These technologies rely on optical communication setups that were proven to be sufficient for performing quantum key distribution (QKD) [7] . Optical setups commonly work over great distances and achieve high bit rate; for instance, the Cambridge Quantum Network achieves a secure key rate of about 2.5 Mb s −1 [8, 9] . Such heavy duty infrastructure is, however, impractical for a plethora of short distance applications which nonetheless require high levels of encryption. Examples include key distribution and renewal between a mobile device and a medical implant, between an electronic car key and its lock or even between a