Characterizing Neutral Modes of Fractional States in the Second Landau Level

TL;DR

This study provides detailed measurements of charge and neutral modes in second Landau level fractional quantum Hall states, offering evidence that supports certain states and excludes others, advancing understanding of non-abelian quasiparticles.

Contribution

It presents new experimental data on quasiparticle charge and neutral modes in the second Landau level, clarifying the nature of these states and supporting the anti-Pfaffian model for the 5/2 state.

Findings

Detected e/3 quasiparticle charge in 8/3 state

Found upstream neutral mode in 8/3 state

No upstream neutral mode in 7/3 state

Abstract

Quasiparticles, which obey non abelian statistics, were predicted to exist in different physical systems, but are yet to be observed directly. Possible candidate states, which are expected to support such quasiparticles, are the {\nu}=8/3, {\nu}=5/2 and {\nu}=7/3 fractional quantum Hall states (in the second Landau level). The non abelian quasiparticles are expected to carry charge and a unique form of a chiral neutral edge mode. Recent measurements in the {\nu}=5/2 state detected quasiparticle charge e/4 and an upstream (opposite to charge transport) chiral neutral mode; both agreeing with a non abelian anti-Pfaffian state; although not excluding the possibility of edge reconstruction as the source for the detected upstream neutral mode and a different type of state. Here we present results of detailed measurements of charge and neutral modes in the main three quantum Hall states of the second Landau level. For the {\nu}=8/3 state we found a quasiparticle charge e/3 and an upstream neutral mode - excluding the possibility of a non abelian Read-Rezayi state and supporting a Laughlin-like state. Such exclusion holds for the hole-conjugate {\nu}=7/3 state as well, in which no upstream neutral mode was detected. This also proves that edge reconstruction was not present in the {\nu}=7/3 state, suggesting its absence also in {\nu}=5/2 state and thus supporting further the non abelian anti Pfaffian state.