Two dimensional characterization of space-momentum entangled photon pairs

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.