Quantum phases and entanglement properties of an extended Dicke model

TL;DR

This paper investigates the quantum phases and entanglement in an extended Dicke model, revealing complex phase structures, quantum phase transitions, and entanglement behaviors across different regimes of atom-field interactions.

Contribution

It introduces a detailed analysis of the phase diagram and entanglement properties of an extended Dicke model, highlighting the crossover between integrable and chaotic regimes.

Findings

Identification of quantum phase transitions and their energy dependences.

Observation of entanglement variations across different phases.

Approximate revival of weak-coupling states in the strong coupling regime.

Abstract

We study a simple model describing superradiance in a system of two-level atoms interacting with a single-mode bosonic field. The model permits a continuous crossover between integrable and partially chaotic regimes and shows a complex thermodynamic and quantum phase structure. Several types of excited-state quantum phase transitions separate quantum phases that are characterized by specific energy dependences of various observables and by different atom-field and atom-atom entanglement properties. We observe an approximate revival of some states from the weak atom-field coupling limit in the strong coupling regime.