Experimental probe of topological orders and edge excitations in the second Landau level

TL;DR

This study probes topological orders and edge excitations in the second Landau level by measuring quasiparticle tunneling at specific filling factors, revealing insights into their nature and the influence of backscattering.

Contribution

It provides experimental data on quasiparticle tunneling at ν=7/3, 8/3, and 5/2, clarifying the nature of these states and their edge excitations, especially regarding non-Abelian versus Abelian quasiparticles.

Findings

At ν=8/3, results align with a particle-hole conjugate Laughlin state.

At ν=5/2, data favor Abelian (3,3,1) or (1,1,3) states.

Backscattering strength significantly affects scaling at ν=7/3.

Abstract

We measure weak quasiparticle tunneling across a constriction in the second Landau level. At $\nu$ = 7/3, 8/3 and 5/2, comparison of temperature and DC bias dependence to weak tunneling theory allows extracting parameters that describe the edges' quasiparticle excitations. At $\nu$ = 8/3, our results are well described by a particle-hole conjugate Laughlin state, but not compatible with proposed non-Abelian quasiparticle excitations. For $\nu$ = 5/2, our measurements are in good agreement with previous experiments and favor the Abelian (3,3,1) or (1,1,3)-states. At these filling factors, we further investigate the influence of the backscattering strength on the extracted scaling parameters. For $\nu$ = 7/3, the backscattering strength strongly affects the scaling parameters, whereas quasiparticle tunneling at $\nu$ = 8/3 and 5/2 appears more robust. Our results provide important additional insight about the physics in the second Landau level and contribute to the understanding of the physics underlying the fractional quantum Hall states at $\nu$ = 7/3, 8/3 and 5/2.