LOSS OF STATE PURITY AND REGULARITY IN THE JAYNES-CUMMINGS MODEL

It is established here that a recently derived asymptotic solution for the Jaynes-Cummings model, for large quasiclassical fields, holds over a length of time which is proportional to nBAR, the average number of photons in the field. When the initial state of the atoms is one of the semiclassical eigenstates, the purity of the atomic state is found to decay with time in a form approximately Gaussian, with a characteristic time proportional to nBAR. When the initial state is not one of the semiclassical eigenstates, the collapses and revivals of the population inversion, for which the model is best known, become irregular also over the same time scale; an explanation for this fact using the asymptotic solution is presented here.