A generalization of the stochastic wave-function method to open quantum systems under the influence of strong laser fields is derived. To this end, quantum-statistical ensembles of reduced state vectors are represented in terms of probability distributions on the projective Hilbert space of the open system. By employing the Floquet expansion of the quantum time evolution, this representation is shown to lead in the Markov approximation to a piecewise deterministic stochastic process for the reduced wave function. The realizations of the stochastic process consist of smooth deterministic parts that are interrupted by sudden jumps. The jump operators are the eigenoperators of the Floquet Hamiltonian and describe instantaneous transitions between Floquet states. Two examples are given that serve to illustrate the method and the stochastic simulation technique of the process.

• Received 28 August 1996

DOI:https://doi.org/10.1103/PhysRevA.55.3101