Electromagnetically induced transparency of an interacting cold Rydberg ensemble

TL;DR

This paper investigates electromagnetically induced transparency in a cold Rydberg gas, demonstrating that weak interactions do not cause decoherence and achieving narrow resonance linewidths.

Contribution

It introduces a density-dependent non-linear model for Rydberg interactions and experimentally shows negligible decoherence at low probe intensities.

Findings

Depopulation of Rydberg state indicates interaction onset

Narrow Rydberg dark resonance with linewidth <600 kHz observed

No interaction-induced decoherence in the weak probe limit

Abstract

We study electromagnetically induced transparency (EIT) of a weakly interacting cold Rydberg gas. We show that the onset of interactions is manifest as a depopulation of the Rydberg state and numerically model this effect by adding a density-dependent non-linear term to the optical Bloch equations. In the limit of a weak probe where the depopulation effect is negligible, we observe no evidence of interaction induced decoherence and obtain a narrow Rydberg dark resonance with a linewidth of <600 kHz, limited by the Rabi frequency of the coupling beam