Many-Body effects and resonances in universal quantum sticking of cold atoms to surfaces

Abstract

The role of shape resonances and many-body effects on universal quantum sticking of ultra cold atoms onto solid surfaces is examined analytically and computationally using an exactly solvable representation of the Dyson equation. We derive the self-energy renormalization of the the transition amplitude between an ultra cold scattering atom and the bound states on the surface in order to elucidate the role of virtual phonon exchanges in the limiting behavior of the sticking probability. We demonstrate that, to first order in the interactions for finite ranged atom-surface potentials, virtual phonons can only rescale the strength of the atom-surface coupling and do not rescale the range of the coupling. Thus, universal sticking behaviour at ultra-low energies is to be expected for all finite ranged potentials. We demonstrate that the onset of the universal sticking behavior depends greatly on the position of the shape resonance of the renormalized potential and for sufficiently low energy shape resonances, deviations from the universal $s(E)\propto\sqrt{E}$ can occur near these energies. We believe that this accounts for many of the low energy sticking trends observed in the scattering of sub-millikelvin H atoms from superfluid $^4$He films.Comment: To appear in 08-Feb-95 issue of The Journal of Chemical Physic