  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.

Quantum Physics