SQUID ratchet: Statistics of transitions in dynamical localization

TL;DR

This paper investigates how thermal noise influences phase space occupation and transition statistics in a SQUID, revealing dynamical localization effects and their impact on voltage behavior.

Contribution

It introduces a detailed analysis of noise-induced dynamical localization in a SQUID, highlighting the role of symmetry breaking and power law tails in residence time distributions.

Findings

Identification of temperature interval with high phase localization

Detection of power law tails in residence time distributions

Discussion of symmetry breaking effects on localization

Abstract

We study occupation of certain regions of phase space of an asymmetric superconducting quantum interference device (SQUID) driven by thermal noise, subjected to an external ac current and threaded by a constant magnetic flux. Thermally activated transitions between the states which reflect three deterministic attractors are analyzed in the regime of the noise induced dynamical localization of the Josephson phase velocity, i.e. there is a temperature interval in which the conditional probability of the voltage to remain in one of the states is very close to one. Implications of this phenomenon on the dc voltage drop across the SQUID are discussed. We detect the emergence of the power law tails in a residence time probability distribution of the Josephson phase velocity and discuss the role of symmetry breaking in dynamical localization induced by thermal noise. This phenomenon illustrates how deterministic-like behaviour may be extracted from randomness by stochasticity itself.