Subharmonic steps and chaotic behavior in rf-biased Josephson junctions

Taking advantage of the software PSpice, we simulated the I-V characteristics of the RCSJ model of Josephson junctions under the radiation of microwave. Integers as well as subharmonic constant-voltage steps are observed, and the dependence of step height on radio frequency (rf) current amplitude was obtained here. Furthermore, we found that the rf-biased junction systems exhibited chaotic behavior at the low rf current amplitude even if the drive frequency is much greater than the plasma frequency of the junction, which affected the subharmonic phase-locking. The results are valuable for the research and application of Josephson junction in voltage standard and microwave detection.