Observed Quantization of Anyonic Heat Flow

TL;DR

This paper reports experimental verification of the quantization of thermal conductance in fractional quantum Hall states, including complex hole-like states, confirming theoretical predictions and highlighting heat transport as a probe of topological properties.

Contribution

The study provides the first extensive measurements confirming the universal quantization of heat conductance in fractional quantum Hall states, including neutral modes and complex hole-like states.

Findings

Confirmed quantization of thermal conductance in fractional quantum Hall states

Verified neutral and charged mode contributions to heat transport

Supported theoretical models for complex hole-like states

Abstract

The quantum of heat conductance of ballistic one-dimensional (1D) channels, being gQ=k0T with k0=pi^2*2kB^2/3h (T - temperature, kB - Boltzmann's constant, h - Planck's constant), is an important fundamental constant. While the quantization of the electrical conductance of 1D ballistic conductors has long been experimentally established, a demonstration of the quantization of thermal conductance proved to be much harder. It has already been accomplished for weakly interacting systems of phonons, photons, and electronic Fermi-liquids. Theoretically, however, the quantization must also hold in strongly interacting systems, such as the Fractional Quantum Hall effect (FQHE), where electrons fractionalize into anyons and chargeless quasiparticles such as neutral Majorana fermions. Since the bulk in the FQHE is incompressible, it is not expected to contribute significantly to the heat conductance, which is determined by chiral 1D edge modes. The thermal conductance reflects topological properties of the FQH electronic systems to which the electrical conductance gives no access. Here, we present results of extensive measurements of the heat conductance in 'particle-like' (Laughlin's) and 'hole-like' fractional states. We verify the universal value of the quantum of thermal conductance of the charged fractional modes as well as for chargeless neutral modes. We also prove the validity of the theoretical predictions for the more complex (and less studied) 'hole-like' states. Heat transport measurements open a door to ample information, not easily accessible by conductance measurements.