The dynamics of quantum discord for two identical qubits in two independent single-mode cavities and a common single-mode cavity are discussed. For the initial Bell state with correlated spins, while the entanglement sudden death can occur, the quantum discord vanishes only at discrete moments in the independent cavities and never vanishes in the common cavity. Interestingly, quantum discord and entanglement show opposite behavior in the common cavity, unlike in the independent cavities. For the initial Bell state with anti-correlated spins, quantum discord and entanglement behave in the same way for both independent cavities and a common cavity. It is found that the detunings always stabilize the quantum discord.
The effects of counter-rotating terms(CRTs)on Rabi splitting and the dynamic evolution of atomic population in the Jaynes–Cummings model are studied with a coherent-state approach.When the coupling strength increases,the Rabi splitting becomes of multi-Rabi frequencies for the initial state of an excited atom in a vacuum field,and the collapses and revivals gradually disappear,and then reappear with quite good periodicity.Without the rotating-wave approximation(RWA),the initial excited state contains many eigenstates rather than two eigenstates under the RWA,which results in the multi-peak emission spectrum.An analytical approximate solution for the strong coupling regime is obtained,which gives a new oscillation frequency and explains the recovery of collapses and revivals due to the equal energy spacing.
