Quasiperiodically driven ratchets for cold atoms
  We investigate experimentally the route to quasiperiodicity in a driven ratchet for cold atoms, and examine the relationship between symmetries and transport while approaching the quasiperiodic limit. Depending on the specific form of driving, quasiperiodicity results in the complete suppression of transport, or into the restoration of the symmetries which hold for a periodic driving. 
R. Gommers, S. Denisov and F. Renzoni