Evolution of field entropy and entanglement in the intensity-dependent two-mode Jaynes-Cummings model

The evolution of the entanglement degree of two-mode fields and atom with the intensity-dependent coupling is investigated by using von Neumann entropy. The results for the initial fields in both coherent states and two-mode squeezed vacuum state are calculated. The influence of the field intensity on the entropy is discussed. It is found that the field and atom are in maximum entanglement but go with periodic pulse disentanglement completely under the condition of strong initial field.