We consider the extension of optical metamaterials to matter waves and then the down scaling of metaoptics to nanometric wavelengths. We show that the generic property of pulsed comoving magnetic fields allows us to fashion the wave-number dependence of the atomic phase shift. It can be used to produce a transient negative group velocity of an atomic wave packet, which results into a negative refraction of the matter wave. Application to slow metastable argon atoms Ar(3P2) shows that the device is able to operate either as an efficient beam splitter or an atomic metalens.

The nonretarded linear-response potential of a metallic cylindrical nanowire in the vicinity at which an atom, assimilated to a fluctuating dipole, is placed is determined using ͑i͒ a complete orthogonal basis set over which the potential inside the solid is expanded and ͑ii͒ the boundary conditions at the solid surface. Exact analytical expressions of the reflection factors are obtained. The dipole-dipole van der Waals energy is then derived by use of the propagator method. This energy is numerically calculated for an argon atom in the vicinity of an aluminum wire. At short distance a repulsive potential, calculated by summing terms in r Ϫ12 over the solid lattice, is added to the previous one. The collision at thermal energies of Ar atoms with the Al wire is then studied. The potential well makes a rainbow effect appear at angles easily accessible experimentally.

van der Waals interactions between an atom and a planar surface exhibit a quadrupolar component in D(2)(z)-D(2)/3 (D, atomic dipole; ź, normal to surface). This coupling is responsible for an atom symmetry break, mixing levels of the same parity such as metastable 3P0, 3P2 levels of rare gas atoms. The strongly exoenergic 3P0-3P2 transition in Ar and Kr is observed by a time-of-flight technique, using as a surface the edge of a copper slit. The results confirm the predicted strong peaking of the angular distribution of inelastically scattered atoms and give a good estimate of the transition probability.