ONE-DIMENSIONAL ARRAYS OF ULTRASMALL TUNNEL-JUNCTIONS WITH ALTERNATING SUPERCONDUCTING AND NORMAL-METAL ISLANDS

We have fabricated and performed measurements on one-dimensional array s of ultrasmal tunnel junctions. These arrays consists of alternating superconducting and normal metal islands. With two gate electrodes, ca pacitively coupled to the aluminum islands, the array is irradiated wi th microwaves of frequency f with an adjustable phase difference betwe en the two microwave signals. In the normal state the I-V characterist ics show clear plateaus at currents I = ne f up to n = 3.