Mesoscopic Noise Theory: Microscopics, or Phenomenology?

TL;DR

This paper critiques existing diffusive models of noise in nonequilibrium systems, especially quantum-confined metals, and proposes an experimental test to validate mesoscopic theory's core claim about noise crossover.

Contribution

It highlights the limitations of current diffusive noise models in quantum-confined systems and introduces a simple experimental test for mesoscopic theory validity.

Findings

Diffusive models inaccurately describe microscopic current fluctuations.

Quantum-confined systems show pronounced deviations from diffusive predictions.

Proposed experimental test to validate mesoscopic noise theory.

Abstract

We argue, physically and formally, that existing diffusive models of noise yield inaccurate microscopic descriptions of nonequilibrium current fluctuations. The theoretical shortfall becomes pronounced in quantum-confined metallic systems, such as the two-dimensional electron gas. In such systems we propose a simple experimental test of mesoscopic validity for diffusive theory's central claim: the smooth crossover between Johnson-Nyquist and shot noise.