Estudo de interferência de elétrons em dispositivos mesoscópicos no limite Hall quântico

Abstract

In this work we introduce the basic concepts required to understand how electronic interferometers work. The interferometers are semiconductor devices based in GaAs/AlGaAs heterojunctions where a high mobility two-dimensional electron gas is formed. The electron gas is confined in a small region of dimension comparable to its Fermi wavelength. In a high magnetic field, the degenerate two-dimensional electron gas develops into one-dimensional magnetoelectric subbands. In this case, the states responsible for the electronic transport are localized near the edges of the device. These edge states play the role of electron beams and quantum point contacts QPCs act as electron beam splitters. The interference patterns are observed in the electric current in one of the electrical contacts as a function of the phase difference between two beams. This phase can be modified by changing the path length or by changing the magnetic flux in the Aharonov-Bohm effect. Current correlations measurements in different contacts of the device are related to the spectral density of the fluctuations in these currents. In this work, we review results of electronic analogues of the Mach-Zehnder and Hanbury Brown-Twiss interferometers that have been reported recently. We also analyze an electronic analogue of the optical Fabry-Perot interferometer that we are trying to make.