Floquet Engineering of Non-Equilibrium Superradiance

TL;DR

This paper reports the discovery of a non-equilibrium superradiant phase in a driven dissipative quantum model, revealing oscillating photon states and potential applications in controllable laser-like devices.

Contribution

It introduces a novel non-equilibrium superradiant phase driven by Floquet states in the Rabi-Dicke model, with implications for optical gain control.

Findings

Identification of a non-equilibrium superradiant phase with oscillating photon states.

Relation of this phase to Floquet state population inversion.

Potential for controllable optical gain in solid-state systems.

Abstract

We demonstrate the emergence of a non-equilibrium superradiant phase in the dissipative Rabi-Dicke model. This phase is characterized by a photonic steady state that oscillates with a frequency close to the cavity frequency, in contrast to the constant photonic steady state of the equilibrium superradiant phase in the Dicke model. We relate this superradiant phase to the population inversion of Floquet states by introducing a Schwinger representation of the driven two-level systems in the cavity. This inversion is depleted near Floquet energies that are resonant with the cavity frequency to sustain a coherent light-field. In particular, our model applies to solids within a two-band approximation, in which the electrons act as Schwinger fermions. We propose to use this Floquet-assisted superradiant phase to obtain controllable optical gain for a laser-like operation.