Onset of chaos in intrinsic Josephson junctions

Abstract

It is demonstrated through numerical simulations that stacks of coupled Josephson junctions exhibit interesting chaotic behavior. A detailed analysis of this chaos is made through computation of the current–voltage characteristics, Lyapunov exponents, Poincaré sections and bifurcation diagrams. The onset of chaos through changes in temperature is modeled by varying the temperature dependent dissipation parameter. Under certain conditions a breakpoint region is found in the current–voltage characteristic. The onset of chaos within this region is initiated though a single period doubling bifurcation that is caused by a parametric resonance which leads to the creation of a longitudinal plasma wave with half the Josephson frequency. The chaotic part of the breakpoint region is approached via a quasi-periodic region. The quasi-periodicity can be understood as a beating phenomenon that occurs when an additional modulating frequency, which is not an integer multiple of the longitudinal plasma frequency, appears.