Stored light and EIT at high optical depths

TL;DR

This paper explores methods to improve electromagnetically induced transparency (EIT) and light storage at high atomic densities by mitigating radiation trapping using nitrogen buffer gas and specialized cell geometry, revealing both benefits and challenges.

Contribution

It presents a preliminary experimental study demonstrating two strategies to reduce radiation trapping effects in high optical depth EIT experiments.

Findings

Nitrogen buffer gas helps reduce radiation trapping.

Long, narrow cell geometry mitigates radiation trapping.

Distortion of EIT lineshapes occurs at high optical depth due to four-wave mixing.

Abstract

We report a preliminary experimental study of EIT and stored light in the high optical depth regime. In particular, we characterize two ways to mitigate radiation trapping, a decoherence mechanism at high atomic density: nitrogen as buffer gas, and a long, narrow cell geometry. Initial results show the promise of both approaches in minimizing radiation trapping, but also reveal problems such as optical pumping into trapped end-states. We also observe distortion in EIT lineshapes at high optical depth, a result of interference from four-wave mixing. Experimental results are in good qualitative agreement with theoretical predictions.