Coherent manipulation of normal and Andreev fermions

Abstract

A large part of condensed matter physics concerns itself with understanding the behaviour of electrons in solids and finding ways to control them. However, in mesoscopic systems (i.e., systems with nanometer to micrometre scale), the behaviour of electrons is difficult to predict through the Schrödinger equation. Instead, it is often more fruitful to use an approximate semiclassical theory that re-introduces the concept of particle trajectories into the quantumworld. These trajectories not only depend on the applied external fields but also on the Fermi surface of the material itself. The control over the Fermi surface allows to engineer electron trajectories not present in classical physics and therefore leads to new novel phenomena. For example, in highly anisotropic materials with open Fermi surfaces, the semiclassical trajectories of electrons in a magnetic field are no longer closed but instead move in an oscillating open trajectory that travels from one sample edge to the next. These open trajectories result in magnetoresistance oscillations with a period proportional to the flux passing through the sample—similar to the Aharonov–Bohm effect. However, unlike the Aharonov–Bohm effect, the magnetoresistance oscillations here are not due to interference effects....