Quantum correlation of light scattered by disordered media

TL;DR

This paper theoretically investigates how multiple scattering in disordered media can generate quantum correlations from Gaussian light inputs, revealing that most Gaussian states produce various forms of quantum correlations, unlike coherent states.

Contribution

It provides a theoretical framework for understanding quantum correlation generation in disordered media, highlighting the role of different Gaussian input states and characterizing correlations with multiple measures.

Findings

Single mode coherent states do not produce quantum correlations.

Any other Gaussian input state can generate quantum correlations.

Thermal states produce non-zero quantum discord.

Abstract

We study theoretically how multiple scattering of light in a disordered medium can spontaneously generate quantum correlations. In particular we focus on the case where the input state is Gaussian and characterize the correlations between two arbitrary output modes. As there is not a single all-inclusive measure of correlation, we characterise the output correlations with three measures: intensity fluctuations, entanglement, and quantum discord. We found that, while a single mode coherent state input can not produce quantum correlations, any other Gaussian input will produce them in one form or another. This includes input states that are usually regarded as more classical than coherent ones, such as thermal states, which will produce a non zero quantum discord.