PHASE-LOCKING CHAOS IN LONG JOSEPHSON-JUNCTIONS

The dynamical behaviour of a fluxon in a long Josephson junction in the presence of an external microwave field is studied by means of a two dimensional map. The map shows that fluxon oscillations may become chaotic through a sequence of period doubling bifurcations. This chaos appears in the central portion of a subharmonic rf-induced step in the current-voltage characteristic and may be observable in a real junction both as a deformation of the step and as a broadening of the linewidth of the emitted radiation, as the bias point is moved from the edges toward the centre of the step. © 1990.