Flying Islands

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
Absorption pictures of atoms after a number of kicks

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:

Experimental realization of a quantum ratchet through phase modulation
D. H. White, S. K. Ruddell, and M. D. Hoogerland
Phys. Rev. A 88, 063603 – Published 3 December 2013