Three key questions on fractal conductance fluctuations: Dynamics, quantization, and coherence

Abstract

Recent investigations of fractal conductance fluctuations (FCF) in electron billiards reveal crucial discrepancies between experimental behavior and the semiclassical Landauer-Buttiker (SLB) theory that predicted their existence. In particular, the roles played by the billiard's geometry, potential profile, and the resulting electron trajectory distribution are not well understood. We present new measurements on two custom-made devices----a ``disrupted'' billiard device and a ``bilayer'' billiard device---designed to directly probe these three characteristics. Our results demonstrate that intricate processes beyond those proposed in the SLB theory are required to explain FCF.