ORDER AND TURBULENCE IN RF-DRIVEN JOSEPHSON-JUNCTION SERIES ARRAYS

We study underdamped Josephson junction series arrays that are globally coupled through a resistive shunting load and driven by an rf bias current. We find coherent, ordered, partially ordered, and turbulent regimes in the I-V characteristics. The ordered regime corresponds to giant Shapiro steps. In the turbulent regime there is a saturation of the broadband noise for a large number of junctions. This corresponds to a breaking of the law of large numbers already seen in globally coupled maps. Coexisting with this, we find an emergence of novel pseudosteps in the I-V characteristics.