New Insight into the Fluctuations of the Moving Vortex Lattice: Non-Gaussian Noise and Levy Flights

TL;DR

This study investigates voltage noise in superconducting Niobium micro-bridges, revealing non-Gaussian fluctuations and Levy flight behavior influenced by inhomogeneities and artificial pinning arrays, especially at low bias currents.

Contribution

It provides the first analysis of Levy flight-like noise in vortex motion and highlights the impact of spatial inhomogeneities and artificial pinning on noise statistics.

Findings

Voltage noise deviates from Gaussian at low currents.

Artificial pinning induces non-stationary, Levy flight-like fluctuations.

Inhomogeneities significantly influence vortex noise behavior.

Abstract

We report measurements and analysis of the voltage noise due the to vortex motion, performed in superconducting Niobium micro-bridges. Noise in such small systems exhibits important changes from the behavior commonly reported in macroscopic samples. In the low biasing current regime, the voltage fluctuations are shown to deviate substantially from the Gaussian behavior which is systematically observed at higher currents in the so called flux-flow regime. The responsibility of the spatial inhomogeneities of the critical current in this deviation from Gaussian behavior is emphasized. We also report on the first investigation of the effect of an artificial pinning array on the voltage noise statistics. It is shown that the fluctuations can lose their stationarity, and exhibit a Levy flight-like behavior.