Resonances between fluxons and plasma waves in underdamped Josephson transmission lines of stripline geometry

We present experiments and theoretical studies on the propagation of Josephson fluxons and electromagnetic waves in parallel arrays of Josephson junctions in the limit of small discreteness. Locking between the fluxon rotation frequency and the frequency of the radiated electromagnetic waves leads to a series of resonances, which we observe on the dc-current-voltage characteristics of the arrays. The arrays consist of small Josephson junctions embedded in an annular superconducting stripline. The experimental data are analyzed using the discrete sine-Gordon model and an extension by including a capacitive interaction between neighboring Josephson junctions. We compare experimental data with both analysis and numerical simulations and find an excellent quantitative agreement.