Multimode-polariton superradiance via Floquet engineering

TL;DR

This paper demonstrates how Floquet engineering enables the creation of multimode polaritons in a cavity-atom system, leading to superradiance and self-organization in ultracold atomic ensembles.

Contribution

It introduces a novel method to achieve multimode Floquet polaritons with strong atom-photon coupling and explores the transition to superradiance via laser drive modulation.

Findings

Multimode Floquet polaritons can be realized with strong dispersive coupling.

Avoided crossings between polaritons indicate mode interactions.

Transition to superradiance occurs at high drive intensities.

Abstract

We consider an ensemble of ultracold bosonic atoms within a near-planar cavity, driven by a far detuned laser whose phase is modulated at a frequency comparable to the transverse cavity mode spacing. We show that a strong, dispersive atom-photon coupling can be reached for many transverse cavity modes at once. The resulting Floquet polaritons involve a superposition of a set of cavity modes with a density excitation of the atomic cloud. The mutual interactions between these modes lead to distinct avoided crossings between the polaritons. Increasing the laser drive intensity, a low-lying multimode Floquet polariton softens and eventually becomes undamped, corresponding to the transition to a superradiant, self-organized phase. We demonstrate the stability of the stationary state for a broad range of parameters.