  The decoherence of two qubits, coupled with one-mode cavity separately, has
been investigated exactly. The results show that, for the resonant case, the
decoherence behavior of system is similar to Markovian case when the coupling
strength is weak, while the concurrence vanishes in finite time and might
recover fractional initial entanglement before it permanently vanishes when the
coupling strength is strong. And for detuning case, the entanglement could
periodically recover after a period of time from its disappearance. These
results are quite different from that of system subjected to Jaynes-Cummings
model.
