Quantum vortex dynamics in granular superconducting films

Abstract

We study the quantum (zero-temperature) dynamics of vortices in a granular film, which we model as a square lattice of superconducting grains, weakly coupled by Josephson junctions. The model takes into account the capacitance to the ground and between nearest-neighbor grains, as well as the special features related to the tunneling of quasiparticles. Starting from the general model, we derive and discuss different approximate models. We investigate the dissipation in the motion of the vortices, which results from excitation of acoustic modes and particularly, of quasiparticles.