Revisiting Coulomb diamond signatures in quantum Hall interferometers

TL;DR

This paper reveals that Coulomb diamond signatures in quantum Hall interferometers can be explained by a nanoscale Fabry-Pérot interferometer model, challenging traditional interpretations and enabling advanced device engineering.

Contribution

It introduces a new model attributing Coulomb diamond features to a quantum Hall interferometer, providing a unified explanation for diamond and checkerboard patterns.

Findings

Diamond and checkerboard patterns are explained by a tunable interferometer model.

Transition between signatures is controlled by interferometer size and tunneling probabilities.

The interpretation suggests revisiting previous experimental data on Coulomb blockade phenomena.

Abstract

Coulomb diamonds are the archetypal signatures of Coulomb blockade, a well-known charging effect mainly observed in nanometer-sized "electronic islands" tunnel-coupled with charge reservoirs. Here, we identify apparent Coulomb diamond features in the scanning gate spectroscopy of a quantum point contact carved out of a semiconductor heterostructure, in the quantum Hall regime. Varying the scanning gate parameters and the magnetic field, the diamonds are found to smoothly evolve to checkerboard patterns. To explain this surprising behavior, we put forward a model which relies on the presence of a nanometer-sized Fabry-P\'erot quantum Hall interferometer at the center of the constriction with tunable tunneling paths coupling the central part of the interferometer to the quantum Hall channels running along the device edges. Both types of signatures, diamonds and checkerboards, and the observed transition, are reproduced by simply varying the interferometer size and the transmission probabilities at the tunneling paths. The new proposed interpretation of diamond phenomenology will likely lead to revisit previous data, and opens the way towards engineering more complex interferometric devices with nanoscale dimensions.