Quantum depinning of a pancake vortex from a columnar defect

We consider the problem of the depinning of a weakly driven (F much less than F-c) pancake vortex from a columnar defect in a Josephson-coupled superconductor, where F denotes the force acting on the vortex (F-c is the critical force). The dynamics of the vortex is supposed to be of the Hall type. The Euclidean action S-Eucl(T) is calculated in the entire temperature range; the result is universal and does not depend on the detailed form of the pinning potential. We show that the transition from quantum-to-classical behavior is second-order like with the temperature T-c of the transition scaling like F-4/3. Special attention is paid to the regime of applicability of our results, in particular, the influence of the large vortex mass appearing in the superclean limit is discussed.