Diffraction of Atoms by a Transmission Grating

We have demonstrated a novel diffraction grating for atoms. A collimated beam of sodium atoms with a de Broglie wavelength of 17 pm was diffracted by transmission through an array of slits with a spatial period of 0.2 \ensuremath{\mu}m formed in a gold membrane. This is the first reported diffraction of atoms by a fabricated periodic structure. Our transmission grating for atoms can divide or recombine an atomic beam coherently, and may provide the easiest route to the realization of an atom wave interferometer.