Photon number correlation for quantum enhanced imaging and sensing

TL;DR

This review discusses how non-classical photon number correlations in twin beams enable quantum-enhanced imaging and sensing, offering robustness against losses and noise, and enabling applications like sub-shot-noise imaging and quantum radiometry.

Contribution

It highlights the potential and achievements of photon number correlations in twin beams for quantum imaging and sensing, emphasizing phase-insensitive measurements and practical applications.

Findings

Photon number correlations are robust against losses and noise.

Twin beams enable parallel, wide-field quantum imaging.

Non-classical correlations facilitate absolute calibration in radiometry.

Abstract

In this review we present the potentialities and the achievements of the use of non-classical photon number correlations in twin beams (TWB) states for many applications, ranging from imaging to metrology. Photon number correlations in the quantum regime are easy to be produced and are rather robust against unavoidable experimental losses, and noise in some cases, if compared to the entanglement, where loosing one photon can completely compromise the state and its exploitable advantage. Here, we will focus on quantum enhanced protocols in which only phase-insensitive intensity measurements (photon number counting) are performed, which allow probing transmission/absorption properties of a system, leading for example to innovative target detection schemes in a strong background. In this framework, one of the advantages is that the sources experimentally available emit a wide number of pairwise correlated modes, which can be intercepted and exploited separately, for example by many pixels of a camera, providing a parallelism, essential in several applications, like wide field sub-shot-noise imaging and quantum enhanced ghost imaging. Finally, non-classical correlation enables new possibilities in quantum radiometry, e.g. the possibility of absolute calibration of a spatial resolving detector from the on-off- single photon regime to the linear regime, in the same setup.