Unveiling the Hanbury Brown and Twiss effect through Renyi entropy correlations

Adopting a quantum information perspective, we analyse the correlations in the thermal light beams used to demonstrate the Hanbury Brown and Twiss effect. We find that the total correlations measured by the Renyi mutual information match the normalised intensity correlations in the regime of low source intensity. Genuine quantum correlations in the form of discord are relevant in such regime but get washed out with increasing source intensity. This provides a new angle on the issue about the nature--quantum versus classical--of the effect.