Entanglement of two atoms in two-mode Raman coupled model with intrinsic decoherence

Considering intrinsic decoherence, the two-atom two-modeRaman coupled model is investigated in this paper. Utilizing theconstants of motion in this model, we obtain the analytic expressionsof the density operator of the system for investigating the entanglementof two atoms. The speed of entanglement decay increases with theincreasing of the coupling coefficient of one atom. The differencebetween the oscillation periods when the initial state parameter ofatomic subsystem belongs to two intervals becomes smaller with theincreasing of the coupling coefficient of one atom. The increasingof the initial photon number of the second field can hasten thevanishing of entanglement of atomic subsystem. The robustness ofatomic entanglement against decoherence depends on the interval ofthe initial state parameter of atomic subsystem.