Entanglement and Sudden Death for a Nonlinear Two Qubit Interaction with a Single su(1,1) Group

In this context, the entanglement between two qubit interaction with a single su(1, 1) group simultaneously prepared initially in a single-mode thermal state is investigated. By using the atomic and the entropy changes to measuring the entanglement between the present subsystem. In addition the concurrence is used to detect the sudden death phenomenon, the compression between the entropy changes and the concurrence is discussed. The obtained results inference that the behavior of the entropy change is agree with the behavior of the concurrence when we measure the entanglement between the structure of the subsystem.