Asymmetric diffusion in the delta-kicked rotor with broken symmetries
  We report an experimental investigation of momentum diffusion in the delta-function kicked rotor where time symmetry is broken by a two-period kicking cycle and spatial symmetry by an alternating linear potential. The momentum diffusion constant is thus modified by kick-to-kick correlations which show a momentum dependence. We exploit this, and a technique involving a moving optical potential, to create an asymmetry in the momentum diffusion that is due entirely to the chaotic dynamics. 
P. H. Jones, M. Goonasekera, H. E. Saunders-Singer, T. S. Monteiro and   D. R. Meacher