The dynamics of entanglement in two-atom Tavis–Cummings model with non-degenerate two-photon transitions for four-qubits initial atom-field entangled states

The influence of dipole–dipole interaction on the entanglement between two Δ-type artificial atoms interacting with two-mode field via non-degenerate two-photon transitions has been investigated. The atom-field system is assumed to be prepared in four-partite atom-field entangled state. The results show that the entanglement between two atoms can be increased by means of dipole–dipole interaction and for some initial states the entanglement sudden death effect can be weakened.