ZENER TUNNELING IN SMALL JOSEPHSON-JUNCTIONS WITH DISSIPATION

We investigated charging effects in a small-area Josephson tunnel junc tion in a SQUID geometry, biased through high-resistance thin-film lea ds. The Josephson coupling energy E(j) was varied by an external magne tic flux inside the SQUID loop. At a certain value of the current the Zener tunneling rate exceeds that of dissipative relaxation and the sy stem ''jumps'' from the lowest to higher Brillouin zones. The shape of I-V curve and crossover current I-cr are in good agreement with a the ory of Zener tunneling with dissipation.