Information Geometry and Quantum Phase Transitions in the Dicke Model
  We study information geometry of the Dicke model, in the thermodynamic limit. The scalar curvature $R$ of the Riemannian metric tensor induced on the parameter space of the model is calculated. We analyze this both with and without the rotating wave approximation, and show that the parameter manifold is smooth even at the phase transition, and that the scalar curvature is continuous across the phase boundary. 
Anshuman Dey, Subhash Mahapatra, Pratim Roy, Tapobrata Sarkar
cond-mat.stat-mech hep-th physics.optics quant-ph