Energy relaxation in edge modes in the quantum Hall effect

TL;DR

This study introduces an experimental method to measure energy relaxation in chiral 1D edge modes of the quantum Hall effect, revealing state-dependent relaxation behaviors in integer and fractional quantum Hall states.

Contribution

It presents a novel setup for measuring energy relaxation in quantum Hall edge modes using noise analysis at a quantum point contact.

Findings

Energy relaxation observed in all tested QHE states.

Relaxation is mild in particle-like states.

Relaxation is prominent in hole-conjugate states.

Abstract

Studies of energy flow in quantum systems complement the information provided by common conductance measurements. The quantum limit of heat flow in one dimensional (1D) ballistic modes was predicted, and experimentally demonstrated, to have a universal value for bosons, fermions, and fractionally charged anyons. A fraction of this value is expected in non-abelian states. Nevertheless, open questions about energy relaxation along the propagation length in 1D modes remain. Here, we introduce a novel experimental setup that measures the energy relaxation in chiral 1D modes of the quantum Hall effect (QHE). Edge modes, emanating from a heated reservoir, are partitioned by a quantum point contact (QPC) located at their path. The resulting noise allows a determination of the 'effective temperature' at the location of the QPC. We found energy relaxation in all the tested QHE states, being integers or fractional. However, the relaxation was found to be mild in particle-like states, and prominent in hole-conjugate states.