The dynamically asymmetric SQUID: M\"unchhausen effect

We report on a complex zero-temperature decay channel of a classical object in a metastable state coupled to a quantum degree of freedom. This setting can be realized in a dc-SQUID where both Josephson-junctions have identical critical currents I_c but feature strongly asymmetric dynamical parameters; more precisely, selecting both parameters C and 1/R adequately large for one and small for the other junction makes the first junction behave essentially classical but lets quantum effects be present for the second one. The decay process is initiated by the tunneling of the quantum junction, which distorts the trapping potential of the classical junction; the metastable state of the latter then becomes unstable if the distortion is large enough. We present the dynamical phase diagram of this system providing the dependence of this decay channel on the external bias current I and on the coupling strength between the two junctions, determined by the loop inductance L.