# Quantum and Nonlinear Effects in Light Transmitted through Planar Atomic Arrays

## TL;DR

This paper investigates quantum many-body effects in light transmission through planar atomic arrays, revealing how quantum fluctuations influence optical properties and atomic correlations at high densities and near saturation.

## Contribution

It demonstrates that quantum effects are significant in light scattering from atomic arrays and introduces an enhanced semiclassical model that accurately reproduces these effects, enabling analysis of large ensembles.

## Key findings

- Quantum effects are prominent at high densities and near saturation.
- Enhanced semiclassical model accurately predicts light transmission.
- Collective phenomena like Rabi splitting and suppressed reflection observed.

## Abstract

We identify significant quantum many-body effects, robust to position fluctuations and strong dipole--dipole interactions, in the forward light scattering from planar arrays and uniform-density disks of cold atoms, by comparing stochastic electrodynamics simulations of a quantum master equation and of a semiclassical model that neglects quantum fluctuations. Quantum effects are pronounced at high atomic densities, light close to saturation intensity, and around subradiant resonances. We show that such conditions also maximize spin--spin correlations and entanglement of formation for the atoms, revealing the microscopic origin of light-induced quantum effects. In several regimes of interest, an enhanced semiclassical model with a single-atom quantum description reproduces light transmission remarkably well, and permits analysis of otherwise numerically inaccessible large ensembles, in which we observe collective many-body analogues of resonance power broadening, vacuum Rabi splitting, and significant suppression in cooperative reflection from atomic arrays.