In Situ Characterisation of an Optically Thick Atom-Filled Cavity

TL;DR

This paper develops a numerical model to accurately characterize the spectral response of an atom-filled optical cavity, accounting for broadening effects, validated by experiments with warm caesium vapour, aiding quantum light-matter interface design.

Contribution

The paper introduces a numerically optimized theoretical model that predicts the spectral response of high-density atom-filled cavities, including regimes where broadening mechanisms are comparable, validated by experimental data.

Findings

Model accurately predicts cavity spectral response.

Experimental parameters like atom density and broadening are extracted.

Model works well for regimes with similar homogeneous and inhomogeneous broadening.

Abstract

A means for precise experimental characterization of the dielectric susceptibility of an atomic gas inside and optical cavity is important for design and operation of quantum light matter interfaces, particularly in the context of quantum information processing. Here we present a numerically optimised theoretical model to predict the spectral response of an atom-filled cavity, accounting for both homogeneous and inhomogeneous broadening at high optical densities. We investigate the regime where the two broadening mechanisms are of similar magnitude, which makes the use of common approximations invalid. Our model agrees with an experimental implementation with warm caesium vapour in a ring cavity. From the cavity response, we are able to extract important experimental parameters, for instance the ground state populations, total number density and the magnitudes of both homogeneous and inhomogeneous broadening.