Ghost Imaging: What is quantum, what is not

TL;DR

This paper clarifies which aspects of ghost imaging are inherently quantum by analyzing classical and quantum Gaussian sources, showing that image formation is fundamentally classical but quantum sources can enhance resolution and field-of-view.

Contribution

It provides a unified framework distinguishing classical and quantum features in ghost imaging, highlighting conditions where quantum sources offer advantages.

Findings

Ghost-image formation is fundamentally classical.

Quantum sources can improve resolution in near-field.

Quantum sources can enhance field-of-view in far-field.

Abstract

We provide a unified treatment of classical and quantum Gaussian-state sources that unambiguously identifies which features of ghost imaging are strictly quantum mechanical. We show that ghost-image formation is fundamentally classical, with the image being expressible in terms of the phase-insensitive and phase-sensitive cross correlations between the detected fields. We then consider ghost-imaging scenarios with either phase-insensitive or phase-sensitive sources, where the former are always classical but the latter may be classical or quantum mechanical. We show that if their auto-correlations are identical, then a quantum source provides resolution improvement in its near-field and field-of-view improvement in its far field when compared to a classical source.