Multicriticality and quantum fluctuation in generalized Dicke model

TL;DR

This paper investigates a generalized Dicke model with multi-level atoms interacting with a single photonic mode, revealing multicritical points and analyzing how criticality order influences entanglement entropy, thus deepening understanding of quantum phase transitions.

Contribution

It introduces a generalized Dicke model with multi-level atoms, derives analytical conditions for multicriticality, and examines how criticality order impacts entanglement entropy.

Findings

Multicritical points can be analytically characterized in the generalized model.

Higher order criticality leads to stronger atom-photon entanglement.

The model provides insights into quantum phase transitions and multicritical phenomena.

Abstract

We consider an important generalization of the Dicke model in which multi-level atoms, instead of two-level atoms as in conventional Dicke model, interact with a single photonic mode. We explore the phase diagram of a broad class of atom-photon coupling schemes and show that, under this generalization, the Dicke model can become multicritical. For a subclass of experimentally realizable schemes, multicritical conditions of arbitrary order can be expressed analytically in compact forms. We also calculate the atom-photon entanglement entropy for both critical and non-critical cases. We find that the order of the criticality strongly affects the critical entanglement entropy: higher order yields stronger entanglement. Our work provides deep insight into quantum phase transitions and multicriticality.