Chargeless heat transport in the fractional quantum Hall regime

TL;DR

This paper presents a novel experimental approach to directly measure chargeless heat transport in the fractional quantum Hall regime, revealing unexpected upstream heat flow independent of electrical current.

Contribution

It introduces a new method to detect chargeless heat transport and uncovers its non-reversal with electrical current direction in fractional quantum Hall systems.

Findings

Upstream chargeless heat transport observed without electrical current.

Heat transport does not follow the reverse of electrical edge current.

Demonstrates a new aspect of fractional quantum Hall physics.

Abstract

We demonstrate a direct approach to investigate heat transport in the fractional quantum Hall regime. At filling factor of 4/3, we inject power at quantum point contacts and detect the related heating from the activated current through a quantum dot. The experiment reveals a chargeless heat transport from a significant heating that occurs upstream of the power injection point, in the absence of a concomitant electrical current. By tuning in-situ the edge path, we show that the chargeless heat transport does not follow the reverse direction of the electrical current path along the edge. This unexpected heat conduction demonstrates a novel aspect, yet to be elucidated, of the physics in fractional quantum Hall systems.