Collective emission of photons from dense, dipole-dipole interacting atomic ensembles

TL;DR

This paper investigates how dense atomic ensembles emit photons collectively, revealing enhanced emission rates and spectral shifts, with implications for quantum information processing.

Contribution

It provides a detailed analysis of collective emission in high-density atomic ensembles, including spectral broadening, shifts, and methods to excite super-radiant states for quantum interfaces.

Findings

Emission rate is strongly enhanced in elongated clouds.

Spectral broadening and redshift occur due to dipole-dipole interactions.

Efficient excitation of super-radiant states enables quantum communication applications.

Abstract

We study the collective radiation properties of cold, trapped ensembles of atoms. We consider the high density regime with the mean interatomic distance being comparable to, or smaller than, the wavelength of the resonant optical radiation emitted by the atoms. We find that the emission rate of a photon from an excited atomic ensemble is strongly enhanced for an elongated cloud. We analyze collective single-excitation eigenstates of the atomic ensemble and find that the absorption/emission spectrum is broadened and shifted to lower frequencies as compared to the non-interacting (low density) or single atom spectrum. We also analyze the spatial and temporal profile of the emitted radiation. Finally, we explore how to efficiently excite the collective super-radiant states of the atomic ensemble from a long-lived storage state in order to implement matter-light interfaces for quantum computation and communication applications.