THERMAL-ACTIVATION IN UNDERDAMPED PHYSICAL SYSTEMS - THE SUPERCURRENT DECAY OF JOSEPHSON-JUNCTIONS

We have performed, at temperatures ranging between 1.27 and 4.2 K, measurements of the supercurrent decay of Josephson tunnel junctions in order to investigate the thermal activation theory. From the theoretical point of view we get over the framework of the RSJ model taking into account the dependence on voltage and temperature of the. quasiparticle tunnelling. The very good agreement of data with theory confirms the correctness of our assumptions and allows the experimental investigation of the general thermal activation theory in the crossover region between the extremely underdamped regime and the moderate underdamped one.