  We investigate vortex shedding from a moving penetrable obstacle in a highly
oblate Bose-Einstein condensate. The penetrable obstacle is formed by a
repulsive Gaussian laser beam that has the potential barrier height lower than
the chemical potential of the condensate. The moving obstacle periodically
generates vortex dipoles and the vortex shedding frequency $f_v$ linearly
increases with the obstacle velocity $v$ as $f_v=a(v-v_c)$, where $v_c$ is a
critical velocity. Based on periodic shedding behavior, we demonstrate
deterministic generation of a single vortex dipole by applying a short linear
sweep of a laser beam. This method will allow further controlled vortex
experiments such as dipole-dipole collisions.
