Steady state properties of a driven atomic ensemble with non-local dissipation

TL;DR

This paper investigates how non-local dissipation affects the steady state of a driven atomic ensemble, revealing a disconnect between excitation density and photon emission, and showing how spatial coherence emerges from collective decay.

Contribution

It introduces the impact of non-local dissipation on steady state properties, highlighting the formation of spatial coherence and the decoupling of static and dynamic observables.

Findings

Non-local dissipation breaks the link between excited atom density and photon emission rate.

Spatial coherence arises from collective quantum jumps in the steady state.

Static and dynamic observables can behave independently due to non-local decay.

Abstract

The steady state of a driven dense ensemble of two-level atoms is determined from the competition of coherent laser excitation and decay that acts in a correlated way on several atoms simultaneously. We show that the presence of this non-local dissipation lifts the direct link between the density of excited atoms and the photon emission rate which is typically present when atoms decay independently. The non-locality disconnects these static and dynamic observables so that a dynamical transition in one does not necessarily imply a transition in the other. Furthermore, the collective nature of the quantum jump operators governing the non-local decay results in the formation of spatial coherence in the steady state which can be measured by analyzing solely global quantities - the photon emission rate and the density of excited atoms. The experimental realization of the system with strontium atoms in a lattice is discussed.