Local Charge of the nu=5/2 Fractional Quantum Hall State

TL;DR

This paper reports the first observation of localized e/4 quasiparticles at the nu=5/2 fractional quantum Hall state, confirming theoretical predictions and enabling future quantum interferometry experiments.

Contribution

It provides experimental evidence of localized quasiparticles at nu=5/2 and measures their charge ratio relative to other fractional states, supporting theories of non-Abelian anyons.

Findings

Localized quasiparticles at nu=5/2 have charge e/4.

Measured charge ratio of 4/3 between nu=7/3 and nu=5/2 states.

Results agree with theoretical predictions of fractional charges.

Abstract

Electrons in two dimensions and strong magnetic fields effectively lose their kinetic energy and display exotic behavior dominated by Coulomb forces. When the ratio of electrons to magnetic flux quanta in the system is near 5/2, the unique correlated phase that emerges is predicted to be gapped with fractionally charged quasiparticles and a ground state degeneracy that grows exponentially as these quasiparticles are introduced. Interestingly, the only way to transform between the many ground states would be to braid the fractional excitations around each other, a property with applications in quantum information processing. Here we present the first observation of localized quasiparticles at nu=5/2, confined to puddles by disorder. Using a local electrometer to compare how quasiparticles at nu=5/2 and nu=7/3 charge these puddles, we are able to extract the ratio of local charges for these states. Averaged over several disorder configurations and samples, we find the ratio to be 4/3, suggesting that the local charges are e/3 at seven thirds and e/4 at five halves, in agreement with theoretical predictions. This confirmation of localized e/4 quasiparticles is necessary for proposed interferometry experiments to test statistics and computational ability of the state at nu=5/2.