Dynamical vortex transitions in a gate-tunable two-dimensional Josephson junction array

The sudden depinning of vortices with increasing current through a super-semihybrid Josephson junction array results in a burst of differential resistance at integer and half-integer peaks of critical current. A striking feature is the split feature at $f=0$, indicating the absence of vortices at precisely zero field. The flat-topped portion at $f=1/2$ and the slanted top part at $f=1$ also reveal features of how the dynamical transition occurs.