Electron interferometry in quantum Hall regime: Aharonov-Bohm effect of interacting electrons

TL;DR

This study demonstrates persistent h/2e interference oscillations in a quantum Hall Fabry-Perot interferometer, revealing the role of electron interactions and Aharonov-Bohm effects in quantum Hall edge states.

Contribution

It provides experimental evidence of h/2e oscillations in a quantum Hall device, highlighting the impact of electron interactions on interference phenomena.

Findings

h/2e oscillations persist across plateau transitions

Oscillation phase remains continuous at half-filling

Results support Aharonov-Bohm interference of interacting electrons

Abstract

An apparent h/fe Aharonov-Bohm flux period, where f is an integer, has been reported in coherent quantum Hall devices. Such sub-period is not expected for non-interacting electrons and thus is thought to result from interelectron Coulomb interaction. Here we report experiments in a Fabry-Perot interferometer comprised of two wide constrictions enclosing an electron island. By carefully tuning the constriction front gates, we find a regime where interference oscillations with period h/2e persist throughout the transition between the integer quantum Hall plateaus 2 and 3, including half-filling. In a large quantum Hall sample, a transition between integer plateaus occurs near half-filling, where the bulk of the sample becomes delocalized and thus dissipative bulk current flows between the counterpropagating edges ("backscattering"). In a quantum Hall constriction, where conductance is due to electron tunneling, a transition between forward- and back-scattering is expected near the half-filling. In our experiment, neither period nor amplitude of the oscillations show a discontinuity at half-filling, indicating that only one interference path exists throughout the transition. We also present experiments and an analysis of the front-gate dependence of the phase of the oscillations. The results point to a single physical mechanism of the observed conductance oscillations: Aharonov-Bohm interference of interacting electrons in quantum Hall regime.