Quantum correlations in two interacting atom ensembles

The power-law scaling behaviours of the quantum discord and the scaled concurrence are presented in two coupled atom ensembles, which exhibit the Dicke-like quantum phase transition. In the super-excitation phase, the quantum discord reaches its maximum beyond the critical point and then decreases monotonically, which is ascribed to the double-degenerated ground state in the strong coupling limit. However, the scaled concurrence exhibits the maximum atomic quantum entanglement at the critical point. Moreover, we find that the persistence of the quantum discord is suppressed by different asymmetric effects in the super-excitation phase.