  Evanescent matter-waves produced by an atom wave packet incident onto a
repulsive barrier edge can be back-refracted and reconstructed by the
application of negative-index "comoving" potential pulses. One shows that those
collapses and revivals of evanescent matter waves give rise to surface matter
waves and should be observable via atom reflection echoes issued from the
barrier interface. This property, together with the property of inducing
negative refraction, makes such potentials the matter-wave counterpart of
negative-index materials in light optics.
