摘要： The entanglement between two identical two-level atoms successively passing a vacuum or a thermal cavity has been investigated taking into account the detuning. The cases when atoms are initially prepared in the separable two-atom or Bell type entangled atomic states have been considered. It has been shown that thermal ?eld can produce the entanglement between Rydberg atoms successively passing a cavity for all considered initial atomic states. For separable initial atomic states and vacuum state of the cavity the presence of detuning leads to decreasing of the degree of atomic entanglement. For entangled initial atomic states and vacuum state of the cavity the presence of detuning leads to decreasing of the entanglement amplitude oscillations. We have also derived that for thermal ?eld the increasing of the mean photon number leads to decreasing of the entanglement, but the entanglement increases as the detuning increases. For thermal ?eld and small detuning we have established that the e?ect of sudden death and birth of entanglement takes place and that for large detuning such e?ect vanishes. Results of the computer simulation are presented.