We numerically study vortex motion in arrays of over- and under-damped Josephson junctions. We show quantitatively that vortex–vortex interactions (VVI) in a vortex-street are large enough to overcome the pinning potential and cause vortices to move even in a region with no external current. The experiments of van der Zant et al.1 are reinterpreted in terms of VVI without invoking ballistic motion of vortices. The discrepancy with simulations which have all failed to observe any ballistic motion is thus removed. Our results also indicate that the vortex mass is negligible for the McCumber–Stewart parameter, β c < 100.
Vortex Motion Rectification in Josephson Junction Arrays with a Ratchet Potential