Negative refraction for incoherent atomic matter waves

Abstract

In a recent paper [Phys. Rev. Lett. 102, 140403 (2009)], Baudon et al. reported that a comoving potential acting on atoms could mimic negative-index-refraction properties of left-handed photonic metamaterials. We show in this article that a better approximation is necessary in order to describe the real physical system proposed by Baudon et al. We derive analytical formulas and compare their solutions with numerical simulations. It turns out that instead of negative refraction, it is simply atomic reflection that occurs in the above-mentioned comoving potential. Furthermore, we find that the wave packet of the reflected atomic beam by comoving potentials can be narrowed by negative dispersion. Finally, we identify a potential configuration, near the interface with a cubic-type potential barrier, that may lead to the observation of negative refraction with incoherent matter waves.