STOPPED ATOMIC WAVEPACKETS GENERATED BY INTERACTION WITH A SQUARE-PROFILE LASER-BEAM

The propagation of a two-level atomic wavepacket across a monochromati c laser beam is considered. For small incident kinetic energies of the atom, the wave nature of the centre-of-mass motion becomes apparent. For certain situations, we show that one of the dressed states cannot propagate inside the laser beam, giving rise to an evanescent atomic w avepacket. Their characteristic features close to the condition of eva nescent (or non-propagating) wavepackets are analysed. In particular, we present two different situations where almost stopped wavepackets a ppear.