Atom reflection in a tapered magnetic guide

We have constructed a two-wire magnetic atom guide incorporating a tapered section, in which the transverse guiding potential steepens as a function of the position along the guide axis. Atoms are slowed as they move into the tapered section and can become reflected. A classical adiabatic model is used to explain the behavior. The model shows and we experimentally observe that the action of the transverse motion, which is an adiabatic invariant, can be used as a control parameter for the atom reflectivity, allowing us to selectively reflect and trap atoms with large transverse action.