Prethermalization of atoms due to photon-mediated long-range interactions

TL;DR

This paper investigates how atoms in optical resonators undergo prethermalization and self-organization due to photon-mediated long-range interactions, revealing complex dynamics and metastable states influenced by cavity losses.

Contribution

It provides a semiclassical analysis of atomic motion, identifying distinct time scales and non-Gaussian metastable momentum distributions during self-organization.

Findings

Atomic momentum distributions are non-Gaussian during transient regimes.

Self-organization dynamics involve a slow approach to equilibrium over extended time scales.

Stationary momentum distribution follows a Maxwell-Boltzmann form influenced by photon loss rates.

Abstract

Atoms can spontaneously form spatially-ordered structures in optical resonators when they are transversally driven by lasers. This occurs when the laser intensity exceeds a threshold value and results from the mechanical forces on the atoms associated with superradiant scattering into the cavity mode. We treat the atomic motion semiclassically and show that, while the onset of spatial ordering depends on the intracavity-photon number, the stationary momentum distribution is a Maxwell-Boltzmann whose width is determined by the rate of photon losses. Above threshold, the dynamics is characterized by two time scales: after a violent relaxation, the system slowly reaches the stationary state over time scales exceeding the cavity lifetime by several orders of magnitude. In this transient regime the atomic momenta form non-Gaussian metastable distributions, which emerge from the interplay between the long-range dispersive and dissipative mechanical forces of light. We argue that the dynamics of selforganization of atoms in cavities offers a testbed for studying the statistical mechanics of long-range interacting systems.