# Near-resonant light scattering by a sub-wavelength ensemble of identical atoms

## TL;DR

This paper theoretically investigates light scattering by a small ensemble of resonant atoms, revealing that interactions reduce scattering near resonance and cause strong fluctuations, with collective modes dominating behavior.

## Contribution

It introduces a detailed analysis of collective dipole-dipole interactions in sub-wavelength atomic ensembles, highlighting their impact on scattering and fluctuations.

## Key findings

- Interacting atoms scatter less than single atoms near resonance.
- Scattered power exhibits strong fluctuations due to collective effects.
- For small samples with N≥20, properties depend mainly on volume.

## Abstract

We study theoretically the scattering of light by an ensemble of $N$ resonant atoms in a sub-wavelength volume. We consider the low intensity regime so that each atom responds linearly to the field. While $N$ non-interacting atoms would scatter $N^2$ more than a single atom, we find that $N$ interacting atoms scatter less than a single atom near resonance. In addition, the scattered power presents strong fluctuations, either from one realization to another or when varying the excitation frequency. We analyze this counter-intuitive behavior in terms of collective modes resulting from the light-induced dipole-dipole interactions. We find that for small samples, their properties are governed only by their volume when $N\gtrsim 20$.