Numerical simulation of collective phenomena in Josephson junction networks

Collective pinning phenomena of vortices in Josephson junction networks (JJN) in magnetic fields are studied using numerical simulations. We consider two kinds of structure of JJN: a ladder (Josephson junction ladder, JJL) and a two-dimensional square array (Josephson junction array, JJA). For the JJL and JJA with distribution of the strengths of junction critical currents, we investigate the critical current of vortex depinning in the presence of bias currents. On the basis of a theory of collective vortex pinning, it is found that the critical currents for both JJL and JJA show a universal scaling behavior.