Evolution Of Atom And Field Linear Entropies

The linear entropies of atom and field in a two-level atom-field coupling system are investigated. The effects of the atomic initial state on the two linear entropies are discussed . For a coherent field, at the half periodic points of the revivals of the atomic population, the atom evolves into a pure state when the field is strong, while the field linear entropy is directly affected by the initial linear entropy of the atom. For a gray-body field, the phenomenon of revival and collapse is also appeared in the atomic linear entropy under appropriate conditions; however, in this case, the atom develops into a maximally mixed state when its population collapses.