In-Situ Dual-Port Polarization Contrast Imaging of Faraday Rotation in a High Optical Depth Ultracold 87Rb Atomic Ensemble

TL;DR

This paper introduces a dual-port polarization contrast imaging technique for in-situ characterization of high optical depth ultracold rubidium ensembles, revealing the importance of dipole-dipole interactions in modeling light-atom interactions.

Contribution

The paper presents a novel in-situ imaging method that compensates for refraction distortions and accurately characterizes dense atomic ensembles for quantum memory applications.

Findings

Achieved optical depth of 680 on the D1 line.

Identified limitations of independent atom models.

Demonstrated the significance of dipole-dipole interactions.

Abstract

We study the effects of high optical depth and density on the performance of a light-atom quantum interface. An in-situ imaging method, a dual-port polarization contrast technique, is presented. This technique is able to compensate for image distortions due to refraction. We propose our imaging method as a tool to characterize atomic ensembles for high capacity spatial multimode quantum memories. Ultracold dense inhomogeneous Rubidium samples are imaged and we find a resonant optical depth as high as 680 on the D1 line. The measurements are compared with light-atom interaction models based on Maxwell-Bloch equations. We find that an independent atom assumption is insufficient to explain our data and present corrections due to resonant dipole-dipole interactions.