Quantum phases of a multimode bosonic field coupled to flat electronic bands

TL;DR

This paper explores the complex quantum phases arising when a multimode bosonic field interacts with flat electronic bands, revealing a richer physics landscape than the traditional Dicke model, including a continuous transition between superradiant and non-phase transition regimes.

Contribution

It introduces a comprehensive analysis showing the system's behavior interpolates between Dicke and Rabi models, challenging previous assumptions about phase transitions in such systems.

Findings

System interpolates between Dicke and Rabi models

Reveals continuous transition without a sharp phase change

Enriches understanding of light-matter interactions in flat band systems

Abstract

We investigate the quantum phases of systems in which a multimode bosonic field is coupled to the transitions between two flat electronic bands. In the literature, such systems are usually modeled using a single or multimode Dicke model, leading to the prediction of superradiant quantum phase transitions for large enough couplings. We show that the physics of these systems is remarkably richer than previously expected, with the system continuously interpolating between a Dicke model exhibiting a superradiant quantum phase transition and a quantum Rabi model with no phase transition.