Converting Zitterbewegung Oscillation to Directed Motion

Zitterbewegung oscillation (ZB), namely, the jittering center-of-mass motion predicted by free space Dirac (or Dirac-like) equations, has been studied in several different contexts. It is shown here that ZB can be converted to directed center-of-mass motion by a modulation of the Dirac-like equation, if the modulation is on resonance with the ZB frequency. Tailored modulation may also stop, re-launch or even reverse the directed motion of a wavepacket with negligible distortion. The predictions may be examined by current ZB experiments using trapped-ion systems.