title: Thermodynamics and superradiant phase transitions in a three-level Dicke model.
abstract: We analyze the thermodynamic properties of a generalized 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 exists as well. We discuss the free energy and prominent expectation values. The limit of vanishing temperature is discussed as well.
authors.affiliation: Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Hayn
authors.affiliation: Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Brandes