Control of dynamical localization by an additional quantum degree of   freedom
  We identify a new parameter that controls the localization length in a driven quantum system. This parameter results from an additional quantum degree of freedom. The center-of-mass motion of a two-level ion stored in a Paul trap and interacting with a standing wave laser field exhibits this phenomenon. We also discuss the influence of spontaneous emission. 
K. Riedel, P. Torma, V. Savichev, W.P. Schleich (University of Ulm,   Germany)