Dc Electrical Current Generated by Upstream Neutral Modes

Abstract

Quantum Hall phases are gapped in the bulk but support chiral edge modes, both charged and neutral. Here we consider a circuit where the path from the source of electric current to the drain necessarily passes through a segment consisting solely of neutral modes. Surprisingly, we find that upon biasing the source, a dc electric current is detected at the drain. Thus, neutral modes carry information that can be used to nonlocally reconstruct a dc charge current. Our protocol can be used to detect neutral modes, not only the edge modes of a quantum Hall system, but also those that have a non-quantum Hall origin. We conclude with a possible experimental realization of this phenomenon.