Ratchet effects—allowing transport only in a single direction without a biased force— are of great importance in biological systems. Here, we perform experiments on a quantum mechanical analogue of such a system. Our 87Rb Bose-Einstein Condensate (BEC) is exposed to a pulsed standing wave created by two counterpropagating off resonant laser beams: this is an “atom- optics” kicked rotor. The standing wave phase is modulated with every kick, inducing accelerator modes and directed transport
On the bottom in these absorption pictures of atoms after a kick sequence, a stable island can be seen that is accelerated with every kick with 4 recoils per kick.
The results were published here: