Institute for Mathematics and Its Applications
Herre van der Zant, T. U. Delft
We present experimental results on the dynamics of Josephson arrays. One-dimensional arrays of Josephson junctions connected in parallel by superconducting wires are model systems for the discrete, damped sine-Gordon equation. Excellent agreement between theory and experiment is obtained. Resonant steps in the current-voltage characteristics indicate the appearance of phase-locking between small-amplitude linear waves and moving kinks. Other resonant steps occur at higher voltages and are caused by a parametric destabilization of a high-velocity whirling mode. The influence of boundary conditions and the coupling between two discrete sine-Gordon systems have also been investigated. In Josephson ladders, superconducting islands are connected to other islands by three Josephson junctions. Their dynamics is more complicated than that of the 1D sine-Gordon systems. The Josephson ladders are an interesting model system intermediate between the purely 1D systems and 2D Josephson arrays.
Work done in collaboration with M. Barahona, A. E. Duwel, E. Trías, T. P. Orlando, Shinya Watanabe and Steven Strogatz.