STANDING-WAVE PATTERNS OF MICROWAVES PROPAGATING IN JOSEPHSON TUNNEL-JUNCTIONS WITH INTEGRABLE AND CHAOTIC BILLIARD GEOMETRIES

A new experimental system based on electron-beam scanning of Josephson tunnel junctions is introduced for studying standing wave patterns in side resonators with integrable and chaotic billiard geometry. The tun nel junctions are coupled to an external microwave source for controll ed rf injection. Utilizing the process of photon-assisted tunneling, w e obtain two-dimensional images of the local photon absorption density proportional to the square of the rf electric field across the juncti on. We observe forced standing wave patterns of the microwave field wh ich depend sensitively on the boundary conditions and the external dri ving frequency. For rectangular resonators a theoretical model is deve loped for describing the multiple reflections of the microwave at the tunnel junction boundaries.