Non-equilibrium dynamics of the Dicke model for mesoscopic aggregates: signatures of superradiance

TL;DR

This paper investigates the non-equilibrium quantum dynamics of a mesoscopic Dicke model, highlighting signatures of superradiance, including emission bursts and correlated states, relevant for understanding phase transitions in cavity QED systems.

Contribution

It provides a detailed analysis of superradiant phenomena and correlated states in a mesoscopic Dicke model with dissipation, bridging experimental observations and theoretical understanding.

Findings

Identification of short-time observables distinguishing weak and strong correlations.

Observation of superradiant burst followed by relaxation to a correlated stationary state.

Characterization of the crossover as a precursor to phase transition in the Dicke model.

Abstract

In the dissipative quantum dynamics of a mesoscopic aggregate of excited two level systems (atoms) coupled to a single resonance mode of a cavity, two physical phenomena associated with superradiance appear. A pronounced emission peak on short time scales is related to the known superradiant burst of excited atoms cooperatively radiating into free space. It is followed by relaxation to a stationary state of the composite system such that for sufficiently large atom-field coupling a strongly correlated state emerges. The crossover to this state can be interpreted as the precursor of the transition from normal to superradiant phase in the thermodynamic limit of the Dicke Hamiltonian. Motivated by recent experimental activities, these features are investigated in detail for a mesoscopic number of atoms and a cavity embedded in a dissipative medium described by a damped Dicke model. We identify observables and characteristics of the quantum dynamics on shorter time scales which allow to clearly distinguish weakly correlated from strongly correlated Dicke physics.