Onset of chaos in intrinsic Josephson junctions

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.