Spatial Multi-Mode Structure of Atom-Generated Squeezed Light

TL;DR

This paper explores the spatial structure of atom-generated squeezed light, revealing its multi-mode nature through experimental observations and a theoretical model involving Laguerre-Gauss modes.

Contribution

It introduces a theoretical model describing higher-order mode generation in squeezed light from Rb atoms, supported by experimental validation.

Findings

Noise suppression depends on the spatial mask and its position.

The squeezed field exhibits a multi-mode spatial structure.

The theoretical model aligns qualitatively with experimental results.

Abstract

We investigated the spatial distribution of quantum fluctuations in a squeezed vacuum field, generated via polarization self-rotation (PSR) interaction of an ensemble of Rb atoms and a strong near-resonant linearly polarized laser field. We found that the noise suppression is greatly effected by the transverse profile of a spatial mask, placed in both the squeezed field and the local oscillator, as well as its position along the focused beam near the focal point. These observations indicate the spatial multi-mode structure of the squeezed vacuum field. We have developed a theoretical model that describes the generation of higher-order Laguerre-Gauss modes as a result of PSR light-atom interaction. The prediction of this model are in a good qualitative agreement with the experimental measurements.