  The dynamics of the quantum discord for two identical qubits in both 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 behaviors 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
detunnings always stabilize the quantum discord.
