Two-dimensional tunneling in a SQUID

TL;DR

This paper explores a multi-path tunneling mechanism in a SQUID, showing that a wide set of trajectories can enhance tunneling probability beyond traditional single-path models.

Contribution

It introduces the concept of multi-path tunneling in a SQUID, highlighting its dependence on the initial state and its impact on tunneling probability.

Findings

Multi-path tunneling can significantly enhance tunneling probability.

The mechanism depends on the initial quantum state in the potential well.

Traditional main-path tunneling is contrasted with multi-path processes.

Abstract

Traditionally quantum tunneling in a static SQUID is studied on the basis of a classical trajectory in imaginary time under a two-dimensional potential barrier. The trajectory connects a potential well and an outer region crossing their borders in perpendicular directions. In contrast to that main-path mechanism, a wide set of trajectories with components tangent to the border of the well can constitute an alternative mechanism of multi-path tunneling. The phenomenon is essentially non-one-dimensional. Continuously distributed paths under the barrier result in enhancement of tunneling probability. A type of tunneling mechanism (main-path or multi-path) depends on character of a state in the potential well prior to tunneling.