Nature of light correlations in ghost imaging

TL;DR

This paper explores the quantum and classical correlations in thermal light sources used for ghost imaging, revealing that quantum correlations are present even in classical-like sources and influence image quality.

Contribution

It introduces a quantum information approach to distinguish quantum from classical correlations in ghost imaging and links total correlations to imaging performance.

Findings

Quantum correlations exist in thermal light sources used for ghost imaging.

Total correlations in the source beams determine the image quality.

Quantum correlations are relevant in low illumination regimes.

Abstract

We investigate the nature of correlations in Gaussian light sources used for ghost imaging. We adopt methods from quantum information theory to distinguish genuinely quantum from classical correlations. Combining a microscopic analysis of speckle-speckle correlations with an effective coarse-grained description of the beams, we show that quantum correlations exist even in `classical'-like thermal light sources, and appear relevant for the implementation of ghost imaging in the regime of low illumination. We further demonstrate that the total correlations in the thermal source beams effectively determine the quality of the imaging, as quantified by the signal-to-noise ratio.