Modeling noise by jump processes in strong laser-atom interactions

In this paper, a practical scheme for computing time-dependent properties, such as excitation probabilities and dipole correlation functions of a multilevel atom strongly excited by a laser in the presence of noise, is described in detail. The method, which is based on the notion of randomly interrupted, multivalued jump processes, can be used to treat laser phase, amplitude, and/or frequency noise, and fluctuating microfields. The method provides analytic expressions, which are based on eigenvalues and eigenvectors of a finite-dimensional matrix, for time dependence and spectral dependence, and it permits computation of time-dependent fluorescence emitted from atoms excited by a noisy laser. The method is illustrated by application to time-dependent spectra.