Dynamical evolution of a two-level atom in a monomode chaotic field

The dynamical evolution of a two-level atom interacting with a monochromatic chaotic field is expressed in terms of a series of functions of the field photon number n. The series are evaluated in the approximation of large 〈n〉, by using the Stirling numbers of the second kind and their properties. The calculated mean values of atomic parameters show a time behaviour that is quite different from an exponential decay to the steady state. In particular they reach values below the steady state values and then evolve towards the stationary conditions with positive derivative. An evaluation of the decay time in the present scheme is also given for excited atomic states.