Quantum entropy and collapses-revivals phenomenon for a generalized four-level atom interacting with a single-mode field with nonlinearities

In this paper, the evolution of the atom-field entanglement through the von Neumann entropy, furthermore, the collapses-revivals phenomenon in the photon number for a general formalism ⋄-type four-level atom interacting with a single-mode field with nonlinearities through the intensity-dependent atom-field coupling and Kerr-like medium are investigated. A factorization of the initial density operator is assumed, considering the field to be initially in the coherent, pure chaotic and squeezed coherent states, while the atom initially in its uppermost excited state. The dynamical behavior of the atomic entropy and the time evolution of the photon number are analyzed. In particular, the effects of the mean photon number, field distributions, detuning, Kerrlike parameter and the intensity-dependent coupling functional on the entropy and the time evolution of photon number is examined. © 2021 Old City Publishing. All rights reserved.