Dynamics of entanglement and population inversion of two qubits in a hybrid nonlinear system

An analytical solution is obtained when the Kerr medium and Stark shift are considered as nonlinear interaction terms to the system containing two-qubit and two-mode electromagnetic field from the parametric amplifier. Dynamics of the population inversion, cavity-qubit and qubit-qubit entanglements are analyzed under the unitary cavity-qubit interaction, the Kerr medium and the Stark shift. The population inversion of a qubit presents periodic revivals and collapses. The results show that the entanglement and the population inversion as well as the inversion have the same stable intervals, that is, the collapse intervals. It is found that the Kerr medium and the Stark shift may lead to reduction of the periods and the amplitudes of the population inversion and the cavity-qubit/qubit-qubit entanglement. The deteriorated qubit-qubit/cavity-qubit entanglement and the population inversion, due to the Kerr medium, may be increased by increasing the Stark shift and vice versa.