Flux Noise near the Berezinskii-Kosterlitz-Thouless Transition

Abstract

We study the flux noise in Josephson junction arrays in the critical regime above the Berezinskii-Kosterlitz-Thouless transition. In proximity coupled arrays a local ohmic damping for the phases is relevant, giving rise to anomalous vortex diffusion and a dynamic scaling of the flux noise in the critical region. It shows a crossover from white to $1/f$-noise at a frequency ${\omega }_{\xi }\propto {\xi }^{-z}$ with a dynamic exponent $z=2$.

Revised version to be published in JETP Letters