Object Identification Using Correlated Orbital Angular Momentum States

TL;DR

This paper demonstrates a novel method for object identification using correlated orbital angular momentum states of entangled photons, leveraging off-diagonal correlations to recognize spatial signatures efficiently.

Contribution

It introduces the first experimental use of correlated OAM states for real object property measurement, enhancing remote sensing capabilities with high-dimensional quantum states.

Findings

Successful detection of discrete rotational symmetries.

Efficient evaluation of azimuthal Fourier coefficients.

Enhanced information capacity through higher-dimensional OAM space.

Abstract

Using spontaneous parametric down conversion as a source of entangled photon pairs, correlations are measured between the orbital angular momentum (OAM) in a target beam (which contains an unknown object) and that in an empty reference beam. Unlike previous studies, the effects of the object on off-diagonal elements of the OAM correlation matrix are examined. Due to the presence of the object, terms appear in which the signal and idler OAM do not add up to that of the pump. Using these off-diagonal correlations, the potential for high-efficiency object identification by means of correlated OAM states is experimentally demonstrated for the first time. The higher-dimensional OAM Hilbert space enhances the information capacity of this approach, while the presence of the off-diagonal correlations allows for recognition of specific spatial signatures present in the object. In particular, this allows the detection of discrete rotational symmetries and the efficient evaluation of multiple azimuthal Fourier coefficients using fewer resources than in conventional pixel-by-pixel imaging. This represents a demonstration of sparse sensing using OAM states, as well as being the first correlated OAM experiment to measure properties of a real, stand-alone object, a necessary first step toward correlated OAM-based remote sensing.