Dynamical behavior in a circularly symmetric annular Josephson junction

Abstract

The dynamical behavior of a circularly symmetric annular Josephson junction is investigated numerically in this paper. First, in the absence of an applied magnetic field there exists a quasiperiodic route to chaos for the equation φρρ+(1/ρ)φρ-φtt-αφt=sinφ under the action of a feeding current I=I0+I1sinΩ1t when I0=0. Second, the I1−V characteristics of the junction for four different I0 values are calculated, and they exhibit both some noiselike and some steplike current-voltage singularities. The former result from the entire chaotic behavior of the junction, while the latter are produced by integral fluxon-motion modes in the junction. The dynamics studies show that the chaotic state is reached via a quasiperiodic transition from a period-2 state. The I0−V characteristics of the junction for three different I1 values also show the noiselike and steplike current-voltage singularities that correspond to the phase-locked states. Finally, when an external ac magnetic field IH=IH1sinΩ2t is applied, the dynamical behavior is very similar to that in the absence of the external magnetic field. The IH1−V characteristics for three different I0 values and the I0−V characteristics for three different IH1 values are calculated. They also show a steplike current-voltage structure.

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