Density matrix reconstruction of three-level atoms via Rydberg electromagnetically induced transparency

TL;DR

This paper demonstrates a method to reconstruct the full density matrix of a three-level Rydberg atom system using spatially-resolved spectroscopy and imaging, revealing detailed quantum state information and optical properties.

Contribution

It introduces a novel approach combining spectroscopy and imaging to fully reconstruct the density matrix of three-level Rydberg atoms under EIT conditions, enabling detailed spatial quantum state analysis.

Findings

Revealed the spatial profile of Rabi frequencies in the atomic gas.

Mapped the optical susceptibility and Rydberg density across the sample.

Identified the double-peaked optical spectrum and narrow Rydberg resonance.

Abstract

We present combined measurements of the spatially-resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, whilst the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and light degrees of freedom and will facilitate new studies of many-body effects in optically driven Rydberg gases.