In-Situ Dual-Port Polarization Contrast Imaging of Faraday Rotation in a   High Optical Depth Ultracold 87Rb Atomic Ensemble
  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. 
Franziska Kaminski, Nir S. Kampel, Mads P. H. Steenstrup, Axel   Griesmaier, Eugene S. Polzik, and J\"org H. M\"uller
physics.atom-ph physics.atm-clus quant-ph