Numerical analysis of ballistic-electron transport in magnetic fields by using a quantum point contact and a quantum wire

Abstract

We report the numerical analysis of our experimental results for electron-wave propagation from a quantum point contact to a quantum wire. Our numerical method solves the boundary problem of a lattice model, and determines wave functions at an arbitrary site. This method also includes a recursive Green's-function method. Our study found oscillations in the conductance, and magnetic suppression of those oscillations. For a simple model, we simulate the oscillations directly related to the channel number in the quantum wire. To understand the magnetic suppression, we investigate the dependence of the electron-wave propagation on the magnetic field using a realistic model. Numerical results show that a realistic rounded corner at the point-contact and a magnetic field could suppress the oscillations. We also discuss the transition from a classical skipping orbit with clear circular segments and focusing to a quantum edge state along a potential wall.