Quantum effects in collisions of ultracold atoms with walls and nanostructures

We study scattering of ultracold atoms by absorbing surfaces. Loss of flux through inelastic reactions and adsorption is described in an unambiguous and model-independent way by incoming boundary conditions in the semiclassical region near the surface. The near-threshold behaviour of the scattering amplitude is determined by a few parameters of the potential tail beyond the semiclassical region. Investigation of quantum reflection and scattering by flat and spherical surfaces shows that the curvature of the surface strongly influences the range to which the scattering amplitudes are sensitive in the atom-surface interaction.