Eur. Phys. J. D (2012) 66: 227
https://doi.org/10.1140/epjd/e2012-30038-0

Regular Article

In-situ dual-port polarization contrast imaging of Faraday rotation in a high optical depth ultracold ⁸⁷Rb atomic ensemble

¹ Niels-Bohr-Institute, Danish Quantum Optics Center QUANTOP, Copenhagen University, Blegdamsvej 17, 2100 Copenhagen, Denmark
² Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany

^a e-mail: kaminski@nbi.dk

Received: 15 January 2012
Received in final form: 8 June 2012
Published online: 4 September 2012

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.