Control of atomic motion with an atom-optical diode on a ring

We propose a method to manipulate the motion of an atom on a ring by means of an atom diode - a laser valve for one-way atomic motion. Several applications are numerically modelled and illustrated: the direction of motion is reversed if the atom moves initially counterclockwise and left unaltered otherwise; a net clockwise motion is imparted on a wave packet with zero initial velocity; and, combining the diode with a well, we also demonstrate cooling and trapping, since the atom can be efficiently slowed down at each diode crossing until it is finally captured in the well when its energy is below the well threshold.