Application of a commercial blazed grating as a mirror 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 for atoms and molecules has required sophisticated electromagnetic fields, nano-fabrication, or particle cooling because of their inherently short de Broglie wavelength and strong interaction with a surface. We demonstrate that blazed gratings designed for photons can work as a mirror for atoms and molecules of thermal energy with up to 47 % reflectivity when used under grazing incidence conditions. The matter-waves of He atoms are reflected from four blazed gratings of different periods (20, 3.33, and 0.417 m) that are commercially available. The reflection probability from the gratings mounted in an in-plane configuration qualitatively follows the specular reflection probability of the multiple edge-diffraction reflection (MEDR) model [1]. When a wave scatters off an array of half-planes at grazing incidence, it undergoes multiple diffractions over an edge of each half-plane. Within the MEDR model the reflection probability increases with decreasing incidence angle and grating period [1]. This allowed 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 for any neutral particle of 100% reflectivity by tailoring edges of grating and shortening its period. In summary, 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 optical instruments such as interferometers and microscopes.