Collective excitation and decay of waveguide-coupled atoms: from timed Dicke states to inverted ensembles

TL;DR

This paper investigates the collective optical behavior of large atomic ensembles coupled to a nanofiber, demonstrating strong inversion and decay dynamics, advancing understanding of light-matter interactions for quantum technologies.

Contribution

It experimentally achieves high atomic inversion and models the collective decay dynamics in a nanofiber-coupled atomic ensemble, extending beyond weak excitation regimes.

Findings

Achieved about 80% atomic excitation in ensembles of up to 1000 atoms.

Observed and modeled the radiative decay into guided modes.

Validated a cascaded interaction model for strong light-matter coupling.

Abstract

The collective absorption and emission of light by an ensemble of atoms is at the heart of many fundamental quantum optical effects and the basis for numerous applications. However, beyond weak excitation, both experiment and theory become increasingly challenging. Here, we explore the regimes from weak excitation to inversion with ensembles of up to one thousand atoms that are trapped and optically interfaced using the evanescent field surrounding an optical nanofiber. We realize strong inversion, with about 80% of the atoms being excited, and study their subsequent radiative decay into the guided modes. The data is very well described by a simple model that assumes a cascaded interaction of the guided light with the atoms. Our results contribute to the fundamental understanding of the collective interaction of light and matter and are relevant for applications ranging from quantum memories to sources of nonclassical light to optical frequency standards.