Experimental investigation of flux motion in exponentially shaped Josephson junctions

We report an experimental and numerical analysis of exponentially shaped long Josephson junctions with lateral current injection. Quasilinear flux flow branches are observed in the current-voltage characteristic of the junctions in the absence of a magnetic field. A strongly asymmetric response to an applied magnetic field is also exhibited by the junctions. Experimental data are found in agreement with numerical predictions and demonstrate the existence of a geometry-induced potential experienced by the flux quanta in nonuniform width junctions.