Spontaneous photon emission in isolated-core excited Rydberg systems and dynamics of electronic wave packets

In isolated-core excited Rydberg systems the destruction of quantum coherence by spontaneous emission of photons is investigated. For this purpose a theoretical description is developed which is based on a decomposition of the atomic density operator into N-photon contributions. Using methods from multichannel quantum defect theory, the relevant atomic transition amplitudes are represented in the form of semiclassical path representations which are associated with repeated returns of the Rydberg electron to the ionic core. Apart from numerical advantages, this approach also yields a clear physical picture of the intricate interplay between the incoherent photon emission process, the coherent laser-modified electron correlation effects, and the semiclassical aspects of the dynamics of the Rydberg electron. Various examples of this interplay are analyzed within the framework of the developed theoretical tools.