Local noise in a diffusive conductor

TL;DR

This paper introduces a minimally invasive method to measure local noise temperature in a current-biased diffusive conductor, overcoming the challenge posed by current conservation that usually links noise to the entire conductor.

Contribution

The authors develop a technique using a miniature noise probe to obtain local noise temperature measurements in non-equilibrium regimes, extending previous measurement capabilities.

Findings

Successfully measures local noise temperature in diffusive conductors.

Demonstrates noninvasive measurement in strongly non-equilibrium conditions.

Overcomes the fundamental constraint of current conservation in noise measurement.

Abstract

The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive and extends primary local measurements towards strongly non-equilibrium regimes.