Dissipative Phase Transition in the Two-Photon Dicke Model

TL;DR

This paper investigates the dissipative phase transition in the two-photon Dicke model, showing how two-photon loss stabilizes the system and leads to superradiant states, with analytical and numerical insights into symmetry breaking.

Contribution

It provides an analytical description of the phase transition in the two-photon Dicke model using a cumulant expansion, highlighting the role of two-photon loss in stabilization.

Findings

Two-photon loss stabilizes the system and enables superradiant states.

Analytical results agree with exact calculations in the thermodynamic limit.

Wigner function analysis reveals Z4-symmetry breaking.

Abstract

We explore the dissipative phase transition of the two-photon Dicke model, a topic that has garnered significant attention recently. Our analysis reveals that while single-photon loss does not stabilize the intrinsic instability in the model, the inclusion of two-photon loss restores stability, leading to the emergence of superradiant states which coexist with the normal vacuum states. Using a second-order cumulant expansion for the photons, we derive an analytical description of the system in the thermodynamic limit which agrees well with the exact calculation results. Additionally, we present the Wigner function for the system, shedding light on the breaking of the Z4-symmetry inherent in the model. These findings offer valuable insights into stabilization mechanisms in open quantum systems and pave the way for exploring complex nonlinear dynamics in two-photon Dicke models.