Thermodynamics and Superradiant Phase Transitions in a three-level Dicke Model

TL;DR

This paper investigates the thermodynamic behavior of a generalized three-level Dicke model, revealing that finite temperatures induce only first-order phase transitions, unlike the zero-temperature case which also exhibits second-order transitions.

Contribution

The study extends the Dicke model to three-level systems with two bosonic modes, analyzing phase transitions at finite and zero temperatures, highlighting the dominance of first-order transitions at finite temperatures.

Findings

Finite temperature induces only first-order phase transitions.

Zero temperature allows both first- and second-order transitions.

Analysis of free energy and expectation values across phases.

Abstract

We analyse the thermodynamic properties of a generalised Dicke model, i.e. a collection of three-level systems interacting with two bosonic modes. We show that at finite temperatures the system undergoes first-order phase transitions only, which is in contrast to the zero-temperature case where a second-order phase transition exist as well. We discuss the free energy and prominent expectation values. The limit of vanishing temperature is discussed as well.