Direct Schmidt number measurement of high-gain parametric down conversion

TL;DR

This paper presents a method to measure the transverse Schmidt number of high-gain parametric down conversion states using second-order intensity correlations, effective across different propagation regions.

Contribution

It introduces a practical approach to estimate the Schmidt number in bright squeezed vacuum states without requiring full state tomography.

Findings

The method accurately measures the Schmidt number in both near and far field regions.

The approach is efficient and applicable throughout the propagation of the bipartite state.

It simplifies the characterization of high-gain PDC states in quantum optics.

Abstract

In this work we estimate the transverse Schmidt number for the bipartite bright squeezed vacuum state by means of second-order intensity correlation function measurement. Assuming that the number of modes is equal in both beams we determine the Schmidt number considering only one of the subsystems. The obtained results demonstrate that this approach is equally efficient over the whole propagation of the state from the near field to the far field regions of its emitter.