Magneto-Transport as a Probe of Electron Dynamics in Open Quantum Dots

Abstract

Publisher Summary This chapter discusses the use of magneto-transport studies to probe electron dynamics in open quantum dots, which are quasi-zero-dimensional semiconductor structures in which electrical current flow is confined on length scales that approach the size of the electron itself. The transmission properties of these structures are strongly regulated by their quantum mechanical lead openings that inject electrons into the dot in a highly collimated beam. The beam, in turn, only couples favorably to a small set of states within the dot, and, at temperatures where electron phase coherence is maintained over long distances, interference of these states becomes the dominant process in the resulting electrical behavior. A powerful experimental tool for probing the interference is provided by the application of a weak magnetic field that shifts the phase of the electron wave function and sweeps successive dot states past the Fermi surface. The resulting fluctuations in the local density of states are thought to be reflected directly in the magneto-conductance of the dot that exhibits a series of regular oscillations at low temperatures. Numerical simulations reveal the oscillations to be correlated to the recurrence of wave-function scarring within the dots, the details of which are produced by a small number of semi-classical orbits. These orbits appear to be highly stable, a property that is thought to arise from the role of the quantum point contact leads and the discrete quantization within the cavity itself.