SPATIOTEMPORAL CHAOS IN JOSEPHSON-JUNCTION ARRAYS

We investigate the dynamical behavior of chaotic states in two-dimensi onal capacitive Josephson-junction arrays (JJA) driven by uniform exte rnal ac and dc currents via numerical simulations of the resistively-s hunted-junction (RSJ) model. In chaotic states the distribution functi ons for the fluctuating voltages in individual transverse junctions ha ve exponential tails similar to findings for the temperature in fluid turbulence. We present a mechanism for the origin of this behavior in arrays based on the random generation and motion of vortices. We also provide evidence to argue that collectively chaotic behavior does not occur.