An Electronic Mach-Zehnder Interferometer

TL;DR

This paper introduces a novel electronic Mach-Zehnder interferometer operating in high magnetic fields, demonstrating high visibility and sensitivity, and investigates its dephasing behavior through shot noise measurements.

Contribution

It presents the first electronic Mach-Zehnder interferometer functioning in the quantum Hall regime with high visibility and analyzes its dephasing mechanisms.

Findings

Achieves 62% fringe visibility in high magnetic field.

Interference pattern decays with temperature but not due to inelastic scattering.

Operates using a single edge state in a closed geometry.

Abstract

Double-slit electron interferometers, fabricated in high mobility two-dimensional electron gas (2DEG), proved to be very powerful tools in studying coherent wave-like phenomena in mesoscopic systems. However, they suffer from small fringe visibility due to the many channels in each slit and poor sensitivity to small currents due to their open geometry. Moreover, the interferometers do not function in a high magnetic field, namely, in the quantum Hall effect (QHE) regime, since it destroys the symmetry between left and right slits. Here, we report on the fabrication and operation of a novel, single channel, two-path electron interferometer that functions in a high magnetic field. It is the first electronic analog of the well-known optical Mach-Zehnder (MZ) interferometer. Based on single edge state and closed geometry transport in the QHE regime the interferometer is highly sensitive and exhibits very high visibility (62%). However, the interference pattern decays precipitously with increasing electron temperature or energy. While we do not understand the reason for the dephasing we show, via shot noise measurement, that it is not a decoherence process that results from inelastic scattering events.