MULTILEVEL SYSTEMS - SIMULTANEOUSLY FORBIDDEN COMBINATION RESONANCES

A general Floquet approach is used to investigate the nonlinear respon se of a multilevel quantum system driven by a strong, in general off-r esonance, pump field. The response to a weak probe field is studied ne ar the quasienergy interval resonances. A general condition is derived for a phenomenon in which the transition matrix elements for a given pair of Floquet states simultaneously vanish for an infinite number of equally spaced resonances beyond a unique frequency edge. This phenom enon is illustrated with several models involving modulating interacti ons and possibilities for its observation are analyzed.