Superradiant phase transition in the ultrastrong-coupling regime of the two-photon Dicke model
Superradiant phase transition in the ultrastrong-coupling regime of the two-photon Dicke model
The controllability of current quantum technologies allows one to implement spin-boson models where two-photon couplings are the dominating terms of light-matter interaction. In this case, when the coupling strength becomes comparable with the characteristic frequencies, a spectral collapse can take place, i.e., the discrete system spectrum can collapse into a …