MACROSCOPIC TUNNELING IN JOSEPHSON-JUNCTIONS WITH 2-STATE FLUCTUATORS

A theory of macroscopic tunneling in superconducting systems with Josephson junctions with disordered environment is developed. We assume that the two-level systems (TLS's) that are characteristic of any disordered state are present within the junction. The TLS's make transitions due to their interaction with the thermal bath (i.e., electrons and phonons). In this way they modulate the barrier for the macroscopic tunneling. We consider the situation where the bias current across the junction is swept by the external source (by the variation of external magnetic field in the Silver-Zimmerman superconducting quantum interference device). We have calculated the critical-current-distribution function for various values of the ratio of the sweep rate and the TLS transition rates.