The entanglement control in Jaynes-Cummings model

In this paper, the entangled strength of the subsystem of the Jaynes-Cummings model (JCM) is studied. Both the field and the atom are in thermal state. The expression of the entanglement (negativity) and its numerical analysis are shown. The numerical results show that there exists a critical temperature and frequency, the entanglement oscillates with time above a critical temperature and below a critical frequency; the entanglement is different in different subspace and decreases exponentially with the increase of the photon number of the subspace. One can control the entanglement through changing temperature, field frequency and different subspace.