Coherent Reflection of He Atom Beams from Rough Surfaces at Grazing Incidence

Abstract

We report coherent reflection of thermal He atom beams from various microscopically rough surfaces at grazing incidence. For a sufficiently small normal component kz of the incident wavevector of the atom the reflection probability is found to be a function of k z only. This behavior is explained by quantum-reflection at the attractive branch of the Casimir-van der Waals interaction potential. For larger values of kz the overall reflection probability decreases rapidly and is found to also depend on the parallel component kx of the wave-vector. The material specific kx dependence for this classic reflection at the repulsive branch of the potential is discussed in terms of an averagingout of the surface roughness under grazing incidence conditions. atom beams of thermal energies. In these experimental studies classic reflection at the repulsive branch of the potential was considered to be negligible, either because of deexcitation of the metastable atoms [3,4], inelastic scattering or adsorption [5], or surface roughness [6]. Quantum reflection was also theoretically studied, using the long-range Casimir-van der Waals atom-surface potential, indicating that the reflection probability is only a function of k z , the component of the incident wave-vector that is perpendicular to the surface [2].

Nonequilibrium Casimir-Polder plasmonic interactions

“…Because of its simple geometry, particular attention has been devoted to the interaction between an atom and a planar slab. For this configuration, the theoretical predictions have been confirmed by several experiments, based on different setups, including deflection of atomic beams close to surfaces [3], classical and quantum reflection of cold atoms [4][5][6][7] and Bose-Einstein condensates (BECs) [8,9], and dipole oscillations of BECs above dielectric substrates [10,11].…”

Temperature and number evolution of cold cesium atoms inside a wall-coated glass cell

“…The coefficients C 3 and C 4 depend on the polarizability property of the cold cesium atoms and on the dielectric property of the cell surface. Quantum reflection is first experimentally observed in the scattering of 4 He atoms off superfluid helium [27] , and subsequently reported in the reflection measurements of atoms from surfaces mediated by the long-range Casimir potential [28][29] . Furthermore, the observations of collisions between hydrogen atoms and bulk helium reveal that the sticking probability should approach zero as √T, where T is the temperature of the incoming hydrogen atoms [30] .…”

Two-dimensional simulation of quantum reflection

“…Since most analytical treatments of quantum reflection rely on approximations, exact numerical efforts are needed to verify their regime of applicability. In parallel, matter-wave experiments enable tests of CasimirPolder interactions [19,[25][26][27][28][29][30][31][32], that require quantitative simulations to bridge the gap between theory and experiment. A recent study investigates the effect of a periodically driven surface in one dimension [33] using a phenomenological atom-surface CasimirPolder interaction potential.…”

“…the reflection of a quantum object in the absence of a classical turning point [1,2], has attracted an increasing number of studies, triggered by the developments in the field of matter-wave optics for a variety of experimental platforms [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”