Landauer-B\"uttiker formula and Schr\"odinger conjecture

TL;DR

This paper links the steady state entropy flux in a quantum transport system to spectral properties of a Schr"odinger operator, showing the equivalence of a physical transport conjecture with a fundamental spectral theory conjecture.

Contribution

It establishes a connection between the persistence of quantum transport in a finite system and the spectral properties of an associated Schr"odinger operator, relating physical and mathematical conjectures.

Findings

Transport persistence is related to transfer matrix bounds.

The conjecture about transport energies equals the spectrum's support.

Equivalence of the transport conjecture with the Schr"odinger conjecture.

Abstract

We study the entropy flux in the stationary state of a finite one-dimensional sample S connected at its left and right ends to two infinitely extended reservoirs at distinct temperatures T1, T2 and chemical potentials mu1, mu2. The sample is a free lattice Fermi gas confined to a box [0, L] with energy operator -\Delta + v. The Landauer-B\"uttiker formula expresses the steady state entropy flux in the coupled system in terms of scattering data. We study the behavior of this steady state entropy flux in the limit L->infinity and relate persistence of transport to norm bounds on the transfer matrices of the limiting half-line Schr\"odinger operator h. A natural conjecture is that the set of energies at which transport persists in this limit is precisely the essential support of the absolutely continuous spectrum of h. We show that this conjecture is equivalent to the Schr\"odinger conjecture in spectral theory of one-dimensional Schr\"odinger operators, thus giving a physically appealing interpretation to the Schr\"odinger conjecture.