Low-energy scattering of ultracold atoms by a dielectric nanosphere

We theoretically study the low-energy scattering of ultracold atoms by a dielectric nanosphere silica glass levitated in vacuum. The atom and surface interact via dispersion force which strength sensitively depends on polarizability, function, geometry. For cesium rubidium atoms, respectively, we compute atom-surface interaction characterize stationary states taking adsorption onto into account. As energy incoming is lowered, find that differences between quantum classical scatterings emerge two steps. First, quantum-mechanical differential cross section elastic starts to deviate from one at an scale comparable few microkelvin units temperature due de Broglie matter-wave diffraction. Second, are found sections regime lower than nanokelvin, where classically forbidden reflection occurs associated with $s$-wave discrete nature angular momentum. also dependencies properties radius nanosphere. This paper paves way identify understand physical origin effects collisions nanoparticle environmental gas over various temperatures.