The dynamically asymmetric SQUID: M\"unchhausen effect

TL;DR

This paper explores a novel decay mechanism in a dc-SQUID with asymmetric junctions, where quantum tunneling in one junction destabilizes the classical junction, revealing complex interplay between quantum and classical dynamics.

Contribution

It introduces a new decay channel in a coupled quantum-classical system with asymmetric parameters, analyzed through a dynamical phase diagram.

Findings

Decay initiated by quantum tunneling distorts classical potential

Metastability depends on bias current and coupling strength

System exhibits complex quantum-classical interaction behavior

Abstract

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.