Comment on "Counter-propagating charge transport in the quantum Hall effect regime"

TL;DR

This paper reinterprets experimental observations of upstream currents in the nu=2/3 quantum Hall regime, suggesting they are due to neutral modes rather than counter-propagating charge modes, aligning with existing theoretical expectations.

Contribution

It provides an alternative explanation for upstream currents in the nu=2/3 regime, emphasizing the role of upstream neutral modes over charge modes.

Findings

Upstream currents can be explained by neutral modes, not charge modes.

The observed data aligns with the neutral mode explanation.

Upstream charge modes are not necessary to explain the phenomena.

Abstract

Laffont et al. [Science 363, 54-57 (2019)] report an upstream current in the nu=2/3 quantum Hall regime, which, they claim, might be due to a counter-propagating charge mode. We show that this observation can also be explained by the expected upstream neutral mode, without the need for an upstream charge mode. Our results agree with the observed data and explain why the upstream current is observed only in the unpolarized nu=2/3 regime.