Algebraic decay of the survival probability in chaotic helium - art. no. 024701

We demonstrate that the classical helium atom exhibits algebraic decay of t he survival probability in the autoionizing eZe configuration. Excitation t owards asymptotic orbits of marginal stability is identified as the cause o f the nonexponential decay. Since one electron travels along a bound Kepler trajectory of infinite excitation in these orbits, we argue that the class ical decay law will prevail in the quantum dynamics of a wave packet launch ed along the eZe configuration.