A slowed coherent atomic beam as a new source for atomic interferometry

The paper presents an experiment based on an efficient coupling between atomic Zeeman states (for atoms with internal angular momentum) allowed by the quadrupolar component of the surface- induced van der Waals (vdW) interaction. This exo-energetic "vdW - Zeeman" transition provides a tuneable (magnetic field intensity dependent) beam splitter that was theoretically illustrated by the simplest possible interferometer: an atomic counterpart of Fresnel biprism. The velocity - adjustable atomic beam is here coming across two opposite surfaces (single slit of a nano-grating). For a transverse coherent radius large enough, the atom wave packet is strongly inelastically diffracted by the two opposite surfaces at some distances from the slit to yield non localised interference fringes. The calculation has been done for Ar metastable atoms with a grating of 100 nm period and different velocities of the atoms (560 to 10 m/s). Via the interference pattern (Schlieren image), this device should give access to such novel information as the oscillating part of the complex vdW - interaction transition amplitude. This simplest configuration is not sensitive to inertial effect. As a next step, a loop - closing transmission grating was added to realize a new type of compact interferometer.