Resonant macroscopic quantum tunneling in SQUID systems.

A detailed theoretical analysis of the resonant macroscopic quantum tunneling in superconducting quantum interference device systems is presented. Our approach allows us to include the effect of both temperature and sweeping rate of the external flux, and to study the phenomenon both in quasistationary and nonstationary conditions, which can be induced by a fast sweep of the external bias. Moreover we compare our theory with the experimental data of Rouse, Han, and Lukens [Phys. Rev. Lett. {bold 75}, 1614 (1995)] referring to the quasistationary case, while other observable effects are predicted in the nonstationary case. {copyright} {ital 1996 The American Physical Society.}