Dynamics of evanescent matter waves in negative-index media

International audiencenumbers: 03.75.-b Matter Waves 03.75.Be Atom and Neutron Optics 37.10.Gh Atom Traps and Guides 42.25.-p Wave Optics ABSTRACT Semi-evanescent and evanescent matter-waves produced by an atom wave packet impinging a repulsive barrier can be back-refracted and reconstructed by the application of negative-index " comoving " potential pulses. One shows that those collapses and revivals generate a matter wave confined on both sides of the barrier border (" surface matter wave ") and should be observable via the retardation of atom reflection from the barrier interface. This property, joined to the possibility recently demonstrated of inducing negative refraction of atom waves, makes such potentials a matter-wave counterpart of negative-index materials or " meta materials " well-known in light optics

INTERFERENTIAL MONOCHROMATOR FOR NEUTRAL ATOMS

Abstract When a so called "co-moving" magnetic field -i.e. a field moving at a velocity close to the atom ones -is used as a phase shifter in a Stern-Gerlach atom interferometer the resulting accumulated phase shift takes non negligible values for only those atomic velocities which are close to that of the field. The interferometer is then an adjustable interferential velocity filter. This effect has been demonstrated by means of a time-of-flight measurement on a metastable hydrogen atom beam the velocity distribution of which is wide (δv/v = 1). By scanning the field velocity, the velocity distribution of a continuous H* beam is readily obtained. Extension to accelerated magnetic fields and their application to gravimetry are proposed

Differential measurements of metastable Ar(3p5 4s, 3P 0,2) on Ar(3p6, 1S0) collisions at thermal energies

Differential cross-sections for Ar*(3p5 4s, 3P 0,2) on Ar(3p6, 1S0) collisions at thermal energies have been measured in a crossed beam experiment, by a time-of-flight technique. The angular dependence of the scattered intensity and the velocity dependence of the differential cross-section in the backward scattering direction are given.On mesure les sections efficaces différentielles pour la collision Ar*(3p 5 4s, 3P0,2) sur Ar(3p6, 1S 0) aux énergies thermiques dans une expérience de jets croisés utilisant une méthode de temps de vol. On donne la dépendance angulaire de l'intensité diffusée, ainsi que la dépendance en vitesse de la section efficace pour le choc de front

Differential measurements on elastic and rotationally inelastic Ne*( 3P0,2)-H2 collisions at thermal energies

A velocity selected crossed beam experiment, using a double chopping technique, is described. Its resolution is good enough to discriminate rotationally inelastic Ne*(2p53s, 3P0,2) on H2 collisions from purely elastic ones. Elastic (0 → 0) and inelastic (0 → 2) differential cross sections in the C.M. frame are given, for a relative energy of 67 meV.On décrit une expérience de faisceaux croisés dans laquelle la sélection en vitesse est obtenue au moyen d'une technique de double hachage. La résolution est suffisante pour séparer les collisions Ne*(2p53s, 3P 0,2)-H2 accompagnées d'excitation rotationnelle, de celles qui sont purement élastiques. On donne les sections efficaces différentielles mesurées à 67 meV, dans le référentiel du centre de masse, pour les collisions élastiques (J = 0 → J = 0) et rotationnellement inélastiques (J = 0 → J = 2)

Schlieren imaging of nano-scale atom-surface inelastic transition using a Fresnel biprism atom interferometer

Surface-induced exo-energetic inelastic transitions among atomic Zeeman states in a magnetic field (“van der Waals – Zeeman” transitions) are useable as tuneable beam splitters. A transversally coherent atom beam impinging a pair of opposite surfaces (e.g. 2 edges of a slit or of an ensemble of periodic slits) gives rise to two coherently diffracted wave packets. Within the wave packet overlap, non-localised interference fringes of the Young-slit type are predicted. From the diffraction pattern observed in the Fraunhofer regime (Schlieren image), detailed information about the transition amplitude on a scale of a few nanometers should be derived

Metastable rare gas atoms scattered by nano- and micro-slit transmission gratings

The transmission of metastable argon atoms through nano-slit or micro-slit gratings is studied by use of time of flight and angular analysis. This transmission departs from the simple geometric one essentially by two ways: (i) the elastic or diagonal part of the van der Waals (vW) interaction with the solid causes an angular narrowing of the emerging beam; (ii) the off-diagonal vW interaction induces the exothermal fine structure transition $^3 {\rm P}_0\to {^3}{\rm P}_2$ $(\Delta E = 175$ meV) leading to large scattering angles; the resulting angular distribution is very sensitive to the roughness of the surface in the direction of the depth. An extension of these experiments to transversally coherent beams is proposed. It should be considered as a first step towards a new type of interferometer in which the inelastic diffraction makes the gratings work as beam splitters or mirrors