OBSERVATION OF LEVEL STATISTICS AND HEISENBERG-TIME ORBITS IN DIAMAGNETIC RYDBERG SPECTRA

We present experimental level statistics of diamagnetic rubidium Rydbe rg spectra. For different types of classical dynamics, significant cha nges in the corresponding nearest-neighbour spacing distributions are observed which converge to Wigner-like distributions in the chaotic ca se. Numerically predicted torus-hopping is identified. High spectral r esolution allows far the observation of underlying long-period orbits: in the Fourier-transformed excitation spectra which are displayed in a parameter-free way. Furthermore, a strong correlation between oscill ator strength and level distributions is present.