The concept of quantum chaos serves a two-fold purpose when applied to the analysis of complex spectra. First, universal statistical features can be identified and second, non-universal superstructures are related to classical closed orbits. Rydberg spectra - the simplest experimental quantum spectra for quantum chaos studies possible - are presented and analyzed in the above spirit. Signatures of chaotic and regular dynamics are identified. Level versus oscillator strength statistics are analyzed. The nature of the spectral autocorrelation function is discussed in the light of the above findings serving as a bridge to the analysis of exciton quantum well spectra.
H. Held und W. Schweizer: Beyond nearest-neighbor spacing distributions: A new indicator for core-induced chaos, Phys. Rev. Lett. 84, 1160-1163 (2000)