37,753 research outputs found
Mesoscopic Noise Theory: Microscopics, or Phenomenology?
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.Comment: Invited paper, UPoN'99 Conference, Adelaide. 13 pp, no figs. Minor
revisions to text and reference
Ballistic transport is dissipative: the why and how
In the ballistic limit, the Landauer conductance steps of a mesoscopic
quantum wire have been explained by coherent and dissipationless transmission
of individual electrons across a one-dimensional barrier. This leaves untouched
the central issue of conduction: a quantum wire, albeit ballistic, has finite
resistance and so must dissipate energy. Exactly HOW does the quantum wire shed
its excess electrical energy? We show that the answer is provided, uniquely, by
many-body quantum kinetics. Not only does this inevitably lead to universal
quantization of the conductance, in spite of dissipation; it fully resolves a
baffling experimental result in quantum-point-contact noise. The underlying
physics rests crucially upon the action of the conservation laws in these open
metallic systems.Comment: Invited Viewpoint articl
- …