Matter-Wave Diffraction from a Periodic Array of Half Planes and its application to He2 and He3

Abstract

We report on reflection and diffraction of beams of He and D2 from square-wave gratings of 400-μm period and strip widths ranging from 10 to 200 μm at grazing-incidence conditions. In each case we observe fully resolved matter-wave diffraction patterns including the specular reflection and diffracted beams up to the second diffraction order. With decreasing strip width, the observed diffraction efficiencies exhibit a transformation from the known regime of quantum reflection from the grating strips to the regime of edge diffraction from an array of half-planes. The latter is described by a single-parameter model developed previously to describe phenomena as diverse as quantum billiards, scattering of radio waves in urban areas, and reflection of matter waves from microstructures. Our data provide experimental confirmation of the widespread model. Moreover, our results demonstrate that neither classical reflection nor quantum reflection are essential for reflective diffraction of matter waves from a structured solid, but it can result exclusively from half-plane edge diffraction. Furthermore, we applied the diffractive reflection mechanism to the diffraction of fragile He2 and He3 to increase their diffraction efficiencies.

[1] J. H. Lee et al., Phys. Rev. Lett. 122, 040401 (2019).