Observation of Zitterbewegung in Non-Abelian Gauge Field

We experimentally observe Zitterbewegung in a two-dimensional degenerate Fermi gas, in the presence of a synthetic non-Abelian gauge field. We reveal the anisotropic nature of Zitterbewegung, namely, the direction-dependence of the oscillation-amplitude and the frequency of oscillation. To observe these effects, we leverage the momentum-dependence of the energy eigenstates, by introducing a kick to the atomic wave packet. Complete suppression of the Zitterbewegung is observed at special angles in momentum-space, and this phenomenon is understood with the spin-texture of this spin-orbit coupled system. The role of Fermi degeneracy is manifested in the damping of the oscillation.