Two dimensional characterization of space-momentum entangled photon pairs

TL;DR

This paper investigates the spatial entanglement of photon pairs generated via parametric down conversion, analyzing position correlations in near and far fields and testing for non-separability using covariance and Mancini's criterion.

Contribution

It introduces a two-dimensional characterization method for space-momentum entangled photon pairs, including experimental measurement and non-separability testing.

Findings

Confirmed position correlations in near and far fields

Demonstrated non-separability using Mancini's criterion

Discussed the impact of higher order spatial modes

Abstract

Space momentum entangled photon pairs are generated from type II parametric down conversion in a beta barium borate crystal. The correlations in the positions of photons in the near field and far field planes with regard to the generating crystal are observed in both transverse dimensions using scanning fiber probes. The space-momentum correlation is characterized using a covariance description for a bivariate normal distribution and tested for non-separability with Mancini's criterion. The role of higher order spatial modes to observe spatial entanglement between the two photons is discussed.