Collective atom-cavity coupling and non-linear dynamics with atoms with multilevel ground states

TL;DR

This paper explores how multilevel atomic ground states influence collective atom-cavity interactions, revealing non-linear dynamics and altered relaxation behaviors through experimental and theoretical analysis with laser-cooled rubidium atoms.

Contribution

It introduces a model for dynamical atom-cavity coupling in multilevel atoms and demonstrates real-time observation of these effects in a cavity QED setup.

Findings

Dynamical backaction modifies atom-cavity coupling strength.

Non-exponential relaxation dynamics observed experimentally.

Multilevel ground states significantly affect cavity QED behavior.

Abstract

We investigate experimentally and theoretically the collective coupling between atoms with multilevel ground state manifolds and an optical cavity mode. In our setup the cavity field optically pumps populations among the ground states. The ensuing dynamics can be conveniently described by means of an effective dynamical atom-cavity coupling strength that depends on the occupation of the individual states and their coupling strengths with the cavity mode. This leads to a dynamical backaction of the atomic populations on the atom-cavity coupling strength which results in a non-exponential relaxation dynamics. We experimentally observe this effect with laser-cooled $^{87}$Rb atoms, for which we monitor the collective normal-mode splitting in real time. Our results show that the multilevel structure of electronic ground states can significantly alter the relaxation behavior in atom-cavity settings as compared to ensembles of two-level atoms.