Non-Abelian Berry-s phase effects and optical pumping of atoms

We predict experimentally verifiable manifestations of non-Abelian Berry's phase effects for atoms in external collinear electric and magnetic fields. The field strengths are arranged so as to cause accidental degeneracy between atomic states. The relevant theoretical results, which have been presented in detail elsewhere, are summarized and explained. We propose an experiment using optically pumped metastable multiplets of Pb/sup 208/ in an atomic beam apparatus to test these predictions. We estimate required experimental parameters, and conclude that the proposed experiment can realistically be performed. copyright 1987 Academic Press, Inc