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Frederick Green

Publications and source records attributed to Frederick Green.

28 records · Page 2Linked to original sources
arXiv2004

Mesoscopic Transport: The Electron-Gas Sum Rules in a Driven Quantum Point Contact

The nature of the electron gas is characterized, above all, by its multi-particle correlations. The conserving sum rules for the electron gas have been thoroughly studied for many years, and their centrality to the physics of metallic conduction is widely understood (at least in the many-body community). We review the role of the conserving sum rules in mesoscopic transport, as normative criteria for assessing the conserving status of mesoscopic models. In themselves, the sum rules are specific enough to rule out any such theory if it fails to respect the conservation laws. Of greater interest is the capacity of the compressibility sum rule, in particular, to reveal unexpected fluctuation effects in nonuniform mesoscopic structures.

cond-mat.str-el↗
arXiv2003

Landauer formula without Landauer's assumptions

The Landauer formula for dissipationless conductance lies at the heart of modern electronic transport, yet it remains without a clear microscopic basis. We analyze the Landauer formula microscopically, and give a straightforward quantum kinetic derivation for open systems. Some important experimental implications follow. These lie beyond the Landauer result as popularly received.

cond-mat.mes-hall↗
arXiv2003

The Landauer Formula: a Magic Mantra Revisited

We review the conceptual structure of the Landauer theory of electron transport in the light of quantum kinetics, the orthodox framework for describing conductance at all scales. In a straightforward analysis, we assess popular claims for a rational link between Landauer theory on the one hand, and orthodox microscopics on the other. The need to explicitly include inelastic (dissipative) carrier relaxation is key to any well-posed microscopic model of open-system mesoscopic transport.

cond-mat.mes-hall↗
arXiv2002

Mesoscopic Transport as Many-Body Physics

We show that a completely orthodox and conserving Landau-Silin approach to current fluctuations in quantum point contacts accounts for the major, and as yet unexplained, peak structures observed in the QPC experiment of Reznikov et al. [Phys. Rev. Lett. 75, 3340 (1995)], for constant values of source-drain current. Those features are absent from corresponding phenomenological predictions and are unanticipated by Landauer-Buettiker theory. The kinetic origin of the Reznikov et al. noise peaks directly manifests the action of the compressibility sum rule in the electron gas. This rule, in turn, is the outworking of microscopic gauge invariance.

cond-mat.mes-hall↗
arXiv2001

Classical to quantum crossover in high-current noise of one-dimensional ballistic wires

Microscopic current fluctuations are inseparable from conductance. We give an integral account of both quantized conductance and nonequilibrium thermal noise in one-dimensional ballistic wires. Our high-current noise theory opens a very different window on such systems. Central to the role of nonequilibrium ballistic noise is its direct and robust dependence on the statistics of carriers. For, with increasing density, they undergo a marked crossover from classical to strongly degenerate behavior. This is singularly evident where the two-probe conductance shows quantized steps: namely, at the discrete subband-energy thresholds. There the excess thermal noise of field-excited ballistic electrons displays sharp and large peaks, invariably larger than shot noise. Most significant is the nonequilibrium peaks' high sensitivity to inelastic relaxation within the open system. Through that sensitivity, high-current noise provides unique clues to the origin of quantized contact resistance and its evolution towards normal diffusive conduction.

cond-mat.mes-hall↗
arXiv2000

On the "anomalous" resurgence of shot noise in long conductors

There has been renewed interest in the physics of the so-called crossover for current fluctuations in mesoscopic conductors, most recently involving the possibility of its appearance in the passage to the macroscopic limit. Shot noise is normally absent from solid-state conductors in the large, and its anomalous resurgence there has been ascribed to a rich interplay of drift, diffusion, and Coulomb screening. We demonstrate that essentially the same rise in shot noise occurs in a much less complex system: the Boltzmann-Drude-Lorentz model of a macroscopic, uniform gas of strictly noninteracting carriers. We conclude that the "anomalous crossover" is a manifestation of simple kinetics. Poissonian carriers, if driven by a high enough field, cross the sample faster than any scattering time, thus fulfilling Schottky's condition for ideal shot noise.

cond-mat.mes-hall↗
arXiv2000

Comment on ``Anomalous crossover between thermal and shot noise in macroscopic diffusive conductors''

Shot noise is not normally evident in bulk solid-state conductors, since it is strongly attenuated by inelastic collisions. The ``anomalous'' emergence of macroscopic shot noise is discussed in G. Gomila and L. Reggiani, Phys. Rev. B 62, 8068 (2000). We remark on the consistency of this linear diffusive model at the large voltages and currents needed to see the effect.

cond-mat.mes-hall↗
arXiv2000

High-field noise in metallic diffusive conductors

We analyze high-field current fluctuations in degenerate conductors by mapping the electronic Fermi-liquid correlations at equilibrium to their semiclassical non-equilibrium form. Our resulting Boltzmann description is applicable to diffusive mesoscopic wires. We derive a non-equilibrium connection between thermal fluctuations of the current and resistive dissipation. In the weak-field limit this is the canonical fluctuation- dissipation theorem. Away from equilibrium, the connection enables explicit calculation of the excess ``hot-electron'' contribution to the thermal spectrum. We show that excess thermal noise is strongly inhibited by Pauli exclusion. This behaviour is generic to the semiclassical metallic regime.

cond-mat.mes-hall↗
arXiv2000

Coulomb screening in mesoscopic noise: a kinetic approach

Coulomb screening, together with degeneracy, is characteristic of the metallic electron gas. While there is little trace of its effects in transport and noise in the bulk, at mesoscopic scales the electronic fluctuations start to show appreciable Coulomb correlations. Within a strictly standard Boltzmann and Fermi-liquid framework, we analyze these phenomena and their relation to the mesoscopic fluctuation-dissipation theorem, which we prove. We identify two distinct screening mechanisms for mesoscopic fluctuations. One is the self-consistent response of the contact potential in a non-uniform system. The other couples to scattering, and is an exclusively non-equilibrium process. Contact-potential effects renormalize all thermal fluctuations, at all scales. Collisional effects are relatively short-ranged and modify non-equilibrium noise. We discuss ways to detect these differences experimentally.

cond-mat.mes-hall↗