Simulations of interference effects in gated two-dimensional ballistic electron systems

TL;DR

This paper uses detailed quantum simulations to analyze interference effects in gated 2D ballistic electron systems, revealing limitations of semiclassical models and explaining complex conductance behaviors.

Contribution

It provides a comprehensive quantum mechanical simulation approach for interpreting interference experiments in gated 2D electron systems, highlighting the limitations of semiclassical models.

Findings

Conductance vs. gate voltage closely matches experimental data.

Semiclassical models have limited validity in complex geometries.

Unexpected periodicities are due to multiple scattering, not simple interference.

Abstract

We present detailed simulations addressing recent electronic interference experiments, where a metallic gate is used to locally modify the Fermi wave-length of the charge carriers. Our numerical calculations are based on a solution of the one-particle Schroedinger equation for a realistic model of the actual sample geometry, including a Poisson equation based determination of the potential due to the gate. The conductance is determined with the multiprobe Landauer-Buettiker formula, and in general we find conductance vs. gate voltage characteristics which closely resemble the experimental traces. A detailed examination based on quantum mechanical streamlines suggests that the simple one-dimensional semiclassical model often used to describe the experiments has only a limited range of validity, and that certain 'unexpected' periodicities should not be assigned any particular significance, they arise due to the complicated multiple scattering processes occurring in certain sample geometries.