The Role of Interactions in an Electronic Fabry-Perot Interferometer Operating in the Quantum Hall Effect Regime

TL;DR

This study investigates how Coulomb interactions influence interference patterns in an electronic Fabry-Perot interferometer within the quantum Hall regime, revealing charge expulsion and flux behavior dependent on edge channels and magnetic field variations.

Contribution

It demonstrates that Coulomb interactions dominate interference in large-area FPIs, affecting flux and charge detection of quasiparticles in quantum Hall systems.

Findings

Coulomb interactions strongly influence interference patterns.

Inner edge channels show flux decrease with increasing magnetic field.

Charges e and e/3 are expelled, enabling quasiparticle charge detection.

Abstract

Interference of edge channels is expected to be a prominent tool for studying statistics of charged quasiparticles in the quantum Hall effect (QHE) [A. Stern (2008), Ann. Phys. 1:204; C. Chamon et al. (1997), Phys. Rev. B, 55:2331]. We present here a detailed study of an electronic Fabry-Perot interferometer (FPI) operating in the QHE regime [C. Chamon et al. (1997), Phys. Rev. B, 55:2331], with the phase of the interfering quasiparticles controlled by the Aharonov-Bohm (AB) effect. Our main finding is that Coulomb interactions among the electrons dominate the interference, even in a relatively large area FPI, leading to a strong dependence of the area enclosed by the interference loop on the magnetic field. In particular, for a composite edge structure, with a few independent edge channels propagating along the edge, interference of the outmost edge channel (belonging to the lowest Landau level) was insensitive to magnetic field; suggesting a constant enclosed flux. However, when any of the inner edge channels interfered, the enclosed flux decreased when the magnetic field increased. By intentionally varying the enclosed area with a biased metallic gate and observing the periodicity of the interference pattern, charges e (for integer filling factors) and e/3 (for a fractional filling factor) were found to be expelled from the FPI. Moreover, these observations provided also a novel way of detecting the charge of the interfering quasiparticles.