Journal of Mathematical Physics -- October 1985 -- Volume 26, Issue 10, pp. 2529-2539 

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On the semiclassical description of N-level systems interacting with radiation fields

G. A. Raggio and H. S. Zivi

Laboratorium für Physikalische Chemie, ETH Zürich, CH-8092 Zürich, Switzerland

It is shown that the dynamics of an N-level quantum system driven by a classical radiation field can be derived rigorously from an associated fully quantum-mechanical model with the help of an asymptotic limit. By formally expanding the full quantum dynamics around the semiclassical limit, quantum corrections to the semiclassical description are systematically constructed. The observables describing these corrections are shown to exist in any order, and explicit expressions for their time dependence are given.

PACS: 03.65.Bz, 42.50.+q, 12.20.Ds, 03.65.Sq