Superradiant and Lasing States in Driven-Dissipative Dicke Models

TL;DR

This paper explores the phase diagram of a driven-dissipative Dicke model, revealing how superradiant and lasing states are separated by a normal phase, with distinct spectral properties and a route to chaos under combined driving.

Contribution

It provides a comprehensive analysis of superradiance and lasing in a non-equilibrium setting, highlighting the phase separation and spectral differences, and introduces a new route to chaos with mixed driving.

Findings

Superradiant and lasing phases are separated by a normal phase.

Photon distributions are similar in superradiant and lasing states, but spectra differ.

Period-doubling leads to chaos with combined coherent and incoherent driving.

Abstract

We present the non-equilibrium phase diagram of a model which can demonstrate both Dicke--Hepp--Lieb superradiance and regular lasing by varying the coherent and incoherent driving terms. We find that the regions in the phase diagram corresponding to superradiance and standard lasing are always separated by a normal region. We analyse the behaviour of the system using a combination of exact numerics based on permutation symmetry of the density matrix for small to intermediate numbers of molecules, and second order cumulant equations for large numbers of molecules. We find that the nature of the photon distribution in the superradiant and lasing states are very similar, but the emission spectrum is very different. We also show that in the presence of both coherent and incoherent driving, a period-doubling route to a chaotic state occurs.