Frequency locking of Josephson junctions in a surface wave resonator

We report on the design, fabrication, and investigation of a series array of Josephson junctions embedded into the surface wave resonator. The resonator is fabricated by using Au-YBa₂Cu₃O₇ bilayer on yttria-stabilized zirconia bicrystal substrate. The arrays were incorporated into the resonator by meandering the bilayer across a grain boundary. The circuit design and the excitation of the proper resonant mode provides series dc biasing and parallel ac biasing of the JJs array. Experimental results show that microwave current is distributed uniformly along the whole 8 mm long array. In the vicinity of the resonant frequency, almost no difference between the microwave currents in the junctions was found