Coherent tunnelling across a quantum point contact in the quantum Hall regime

TL;DR

This paper demonstrates that a quantum point contact in the quantum Hall regime can function as an interferometer due to a new tunneling mechanism involving a quantum Hall island, opening avenues for novel coherent tunneling devices.

Contribution

It introduces a new interferometric model for QPCs in the quantum Hall regime involving a quantum Hall island and multiple tunneling paths, supported by experimental spectroscopy data.

Findings

QPC can act as an interferometer with specific potential landscapes.

Spectroscopy confirms the interferometric behavior of the QPC.

A new model explains the observed tunneling phenomena involving a quantum Hall island.

Abstract

The unique properties of quantum Hall devices arise from the ideal one-dimensional edge states that form in a two-dimensional electron system at high magnetic field. Tunnelling between edge states across a quantum point contact (QPC) has already revealed rich physics, like fractionally charged excitations, or chiral Luttinger liquid. Thanks to scanning gate microscopy, we show that a single QPC can turn into an interferometer for specific potential landscapes. Spectroscopy, magnetic field and temperature dependences of electron transport reveal a quantitatively consistent interferometric behavior of the studied QPC. To explain this unexpected behavior, we put forward a new model which relies on the presence of a quantum Hall island at the centre of the constriction as well as on different tunnelling paths surrounding the island, thereby creating a new type of interferometer. This work sets the ground for new device concepts based on coherent tunnelling.