Mesoscopic Noise Theory: Microscopies, or Phenomenology?

摘要

We argue, physically and formally, that existing diffusive models of noise yield inaccurate microscopic descriptions of nonequilibrum 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 noise and shot noise.