Abstract
In this paper, the linear entropy and collapse-revival phenomenon through the relation (<(a) over cap (+)(a) over cap > - (n) over bar) in a system of N-configuration four-level atom interacting with a single-mode field with additional forms of nonlinearities of both the field and the intensity-dependent atom-field coupling functional are investigated. A factorization of the initial density operator is assumed, considering the field to be initially in a squeezed coherent states and the atom initially in its most upper excited state. The dynamical behavior of the linear entropy and the time evolution of (<(a) over cap (+)(a) over cap > - (n) over bar) are analyzed. In particular, the effects of the mean photon number, detuning, Kerr-like medium and the intensity-dependent coupling functional on the entropy and the evolution of (<(a) over cap (+)(a) over cap > - (n) over bar) are examined.