Behavior of nonclassical recurrence amplitudes near closed-orbit bifurcations in atoms

Abstract

We report an experimental and computational study of the energy dependence of nonclassical paths in atoms near bifurcations. The experiment employs scaled energy spectroscopy to measure the amplitudes of nonclassical orbits in helium singlet and triplet Stark Rydberg states (20<n<30), close to bifurcations. We have also calculated this behavior for hydrogen. In both cases, the amplitude dependence on energy, just below a bifurcation, is consistent with an exponential function, in accord with theoretical predictions. Five different nonclassical paths have been studied and, in the case of helium but not hydrogen, the effect of interference between real and ghost orbits is found to produce oscillations in the exponential decay with closed orbit type. In the case of hydrogen, the n dependence of the decay exponent has been investigated and a linear relationship is found.