Laser driven superradiant ensembles of two-level atoms near Dicke's regime

TL;DR

This paper reports the experimental observation of superradiant emission from a dense, elongated ensemble of laser-cooled two-level atoms, demonstrating superradiance along the symmetry axis even with orthogonal driving, and comparing results with theoretical models.

Contribution

It provides the first experimental demonstration of superradiance in a near-Dicke regime with a specific geometry and compares findings with advanced theoretical calculations.

Findings

Superradiant emission observed along the symmetry axis.

Superradiance persists despite orthogonal driving laser.

Qualitative agreement with ab-initio, beyond-mean-field calculations.

Abstract

We report the experimental observation of superradiant emission emanating from an elongated dense ensemble of laser cooled two-level atoms, with a radial extent smaller than the transition wavelength. In the presence of a strong driving laser, we observe that the system is superradiant along its symmmetry axis. This occurs even though the driving laser is orthogonal to the superradiance direction. This superradiance modifies the spontaneous emission, and, resultantly, the Rabi oscillations. We also investigate Dicke superradiance in the emission of an almost fully-inverted system as a function of atom numnber. The experimental results are in qualitative agreement with ab-initio, beyond-mean-field calculations.