Applications of commercial optical gratings as mirrors for matter waves

Abstract

Mirrors for atoms and molecules could open new frontiers in matter-wave optics with neutral particles. However, the realization of such components has required sophisticated electromagnetic fields, nano-fabrication, or particle cooling because of inherently short de Broglie wavelengths of atoms and molecules and their strong interaction with a surface. We demonstrate that blazed gratings designed for light waves can work as mirrors for atoms and molecules of thermal energy with up to 47% reflectivity when used under grazing incident conditions. The matter-waves of He atoms are reflected from blazed gratings of different periods (20, 3.33, and 0.417 µm) that are commercially available. The specular reflection probability is well described by the multiple edge- diffraction reflection (MEDR) model. When a wave scatters off an array of half-planes at grazing incidence, it undergoes multiple diffractions by the half-plane edges. Within the MEDR model the reflection probability increases with decreasing incidence angle and grating period. This allows us to observe reflection of fragile He clusters (He2 and He3) with the 417-nm-period grating, which implies that the grating mirror based on the MEDR mechanism can also work for other exotic particles, such as antihydrogen atoms. It will be possible to prepare an almost perfect mirror (close to 100% reflectivity) for a neutral particle by tailoring the edges of a grating and shortening its period. Our experiment and analysis show that commercial optical blazed gratings can serve as a mirror in matter-wave optics, which paves the way toward developing various matter-wave-optical instruments.