Measuring different types of transverse momentum correlations in the biphoton's Fourier plane

TL;DR

This paper explores how spatial correlations of photon pairs generated via spontaneous parametric down-conversion can be positive or negative, depending on scanning direction and polarization, offering new ways to observe and tune these correlations.

Contribution

It provides both theoretical and experimental insights into controlling and observing different types of transverse momentum correlations in biphotons.

Findings

Correlations can be positive or negative based on scan direction.

Polarization post-selection influences correlation type.

Method offers a new way to tune and observe spatial correlations.

Abstract

In this work, we present a theoretical and experimental study about the spatial correlations of paired photons generated by type-II spontaneous parametric down-conversion. In particular, we show how these correlations can be positive or negative depending on the direction in which the far field plane is scanned and the polarization post-selected. Our results provide a straightforward way to observe different kind of correlations, that complement other well known methods to tune the spatial correlations of paired photons.