Voltage fluctuations on a superconductor grain attached to a quantum wire

TL;DR

This paper investigates how superconducting phase fluctuations influence voltage noise and charge fluctuations in a superconductor connected to a one-dimensional normal conductor, revealing characteristic power-law behaviors in the noise spectrum.

Contribution

It provides a theoretical analysis of voltage and charge fluctuation spectra in superconductor-normal conductor systems, highlighting the impact of phase fluctuations on noise characteristics.

Findings

Charge fluctuations exhibit a 1/ω power spectrum at zero temperature.

At higher temperatures, the noise spectrum shifts to a 1/ω^2 behavior.

Superconducting phase fluctuations induce power-law noise responses.

Abstract

When a finite superconductor is in contact with a 1D normal conductor, superconducting phase fluctuations lead to power-law response of the normal subsystem. As a result, the charge fluctuations on the superconductor at zero temperature have logarithmic correlator and a 1/\omega power spectrum (1/f-noise). At higher temperatures 1/\omega is pushed to the high frequency region, and 1/\omega^2 behavior prevails.