Rydberg Electrons in Crossed Fields:. A Paradigm for Nonlinear Dynamics Beyond Two Degrees of Freedom

Systems with two degrees of freedom are comparatively well-understood in contrast to the other, more common, variety which requires more than two degrees of freedom for its description. These multidimensional systems will be the focus of this article, which deals with quantal problems in the Correspondence Principle limit. Our systems of choice are highly excited ("Rydberg") atoms placed in external fields the Hamiltonians of which show soft chaos.