  We present a microscopic approach to the quantum tunneling of vortices. The
formalism characterizes the rate at which a many-body superconducting state
with a vortex in one location makes a transition to a second many-body
superconducting state with a vortex in a second location. The theory is
utilized to study the effect of a d-wave order parameter upon the
directionality of vortex tunneling.
