Algebraic decay of the survival probability in chaotic helium

Abstract

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