Identifying non-abelian anyons in quantum Hall states

Laboratory of Quantum Physics, Topology and Correlations
École Polytechnique Fédérale de Lausanne, Switzerland

Quantum Hall effects in 2D electron gas exemplify the earliest class of topological phases in solid state physics, characterized by an insulating bulk and gapless edge excitations. The quantum Hall effect has been a source of many concepts that have become essential in more general quantum many-body problems. The fractional quantum Hall states host fractional charges, neutral excitations, and unlike the integer quantum Hall states, they generally support counter-propagating chiral edge modes. The theoretical and the experimental search for such fractionalized particles continues to attract extensive attention. One reason for the enthusiasm is fundamental - as fractionalization can brilliantly exemplify the rich emergent long-range behavior that many-body systems can exhibit. Another reason is more pragmatic, as certain non-abelian fractionalized excitations form the basis of topological quantum computers that promise inherent immunity against errors. In this talk, I will present the role of neutral modes in the quantum Hall effect, as the highly sought after non-abelian excitations are often “charge-neutral”. Yet, there are bosonic neutral modes that plague the single-particle interferometers in the fractional quantum Hall regime.