Cooperative optical pattern formation in an ultrathin atomic layer

TL;DR

This paper demonstrates how a single atomic layer can spontaneously form complex optical patterns through cooperative nonlinear interactions, without the need for mirrors or cavities, revealing new collective atomic behaviors.

Contribution

It introduces a novel mechanism of pattern formation in an ultrathin atomic layer driven by cooperative nonlinear effects, expanding understanding of non-equilibrium optical phenomena.

Findings

Optical patterns emerge from atomic fluctuations without mirrors or cavities.

Pattern formation is linked to a bistable collective atomic response.

Atomic position fluctuations can be visualized through wave-like distortions.

Abstract

Spontaneous pattern formation from a uniform state is a widely studied nonlinear optical phenomenon that shares similarities with non-equilibrium pattern formation in other scientific domains. Here we show how a single layer of atoms in an array can undergo nonlinear amplification of fluctuations, leading to the formation of intricate optical patterns. The origin of the patterns is intrinsically cooperative, eliminating the necessity of mirrors or cavities, although introduction of a mirror in the vicinity of the atoms significantly modifies the scattering profiles. The emergence of these optical patterns is tied to a bistable collective response, which can be qualitatively described by a long-wavelength approximation, similar to a nonlinear Schr\"odinger equation of optical Kerr media or ring cavities. These collective excitations have the ability to form singular defects and unveil atomic position fluctuations through wave-like distortions.