Decay in an asymmetric SQUID

TL;DR

This paper investigates quantum tunneling in an asymmetric SQUID, revealing a one-dimensional tunneling process influenced by capacitance asymmetry, with unique temperature dependence and transition behaviors.

Contribution

It introduces a model for tunneling in asymmetric SQUIDs where capacitance asymmetry simplifies the process and uncovers unusual temperature effects.

Findings

Tunneling becomes effectively one-dimensional due to capacitance asymmetry.

The temperature dependence of tunneling probability shows a finite slope at zero temperature.

Transitions between thermally assisted tunneling and activation can be abrupt or smooth depending on current.

Abstract

Quantum tunneling in an asymmetric (with strongly different capacitances) SQUID is studied. Since capacitances play a role of masses one phase, related to a large mass, becomes "heavy" and remains always a constant in a tunneling process. Tunneling in an asymmetric SQUID becomes one-dimensional with a condition of optimization of tunneling probability with respect to a value of the "heavy" phase. An unusual temperature dependence of the tunneling probability is obtained. It has a finite slope at zero temperature and a transition between thermally assisted tunneling and pure activation can be not smooth depending on current through a SQUID.