Thermal entanglement in the three-qubit Tavis-Cummings model with many-photon transitions

In this paper, we consider the model consisting of an isolated qubit and two qubits trapped in a lossless cavity and interacting with cavity thermal field via many-photon transitions. We obtain the exact solution of the model under  consideration. On its basis we calculate the negativity as a measure of pair qubits entanglement. It is shown that, for many-photons processes entanglement is stronger than for that in the linear one-photon processes and can suppress the sudden death of qubit-qubit entanglement. The pairwise entanglement transfer between qubits pairs are also observed.