Revisiting the phase transitions of the Dicke model

The Dicke model exhibits a variety of phase transitions. quantum transition from the normal to super-radiant is marked by dramatic change in scaling participation ratio. We find that ground state multifractality manifest ratio as square root full Hilbert space dimension. thermal temperature, for which we obtain an exact analytical expression, strikingly captured mutual information between two spins. In excited within phase, discover new upper cut-off energy; central energy band lower and energies shows distinctly different behaviour. This finding corroborated with aid several eigenvector properties: von Neumann entanglement entropy spins bosons, mean photon number, concurrence spins, Thus unified picture three kinds