On the Dicke model in the Ultra-strong Coupling Regime

The ultra-strong coupling is a fascinating regime of light-matter interaction. It provides a way to study exciting new features in Circuit QED. In the present work, we consider a Dicke Model describing a system of qubits... [ view full abstract ]

The ultra-strong coupling is a fascinating regime of light-matter interaction. It provides a way to study exciting new features in Circuit QED. In the present work, we consider a Dicke Model describing a system of qubits interacting with a single bosonic mode field. We firstly analyze the energy spectrum of the model, for both Cavity QED and Circuit QED systems, in the presence of a Diamagnetic term. We also investigate the Wigner distribution function to analyze the effect of the A² term on the ground state wave function in the ultra-strong coupling regime, and show the entanglement generation and the occurrence of the superradiant phase transition in the thermodynamic limit. We then study the entanglement of this Bi-partite model under the presence of this diamagnetic term. We analyze the phase space properties of our system proving that our system becomes multi-degenerate.  

Keywords: Wigner distribution function, Entanglement, diamagnetic term, Dicke model, Circuit QED.