Non-Abelian anyons at quantum Hall filling 5/2
Does the fractional quantum Hall state observed at filling factor 5/2 host exotic quasiparticles (non-Abelian anyons) whose braiding statistics could form the basis of topological quantum computers, and can this be conclusively demonstrated?
History and references
Partly settled. Some of it is understood, some is still argued about.
Predicted theoretically (Moore-Read Pfaffian state) as a candidate for non-Abelian quasiparticle statistics, the 5/2 fractional quantum Hall state was discovered experimentally in 1987. Interferometry experiments since 2011, refined through the early 2020s, have observed phase signatures (e/4 charge, discrete phase jumps) consistent with non-Abelian statistics, which would make it a natural platform for fault-tolerant topological quantum computing. However, alternative Abelian orderings can mimic some signatures, so the interpretation is still debated among specialists as of the mid-2020s, keeping the question formally open.
A puddle of two-dimensional electrons in a strong magnetic field may be quietly hosting particles that are neither bosons nor fermions but something new, and could power a fundamentally different kind of computer.
Explanations that circulated
- That non-Abelian anyons at nu=5/2 have already been definitively confirmed and used to build a topological qubit — interferometry results as of the mid-2020s are supportive but not universally regarded as a final, unambiguous proof
References
- Interference measurements of non-Abelian e/4 & Abelian e/2 quasiparticle braiding, Kwon, Nakamura, Willett, et al. (interferometry collaborations), arXiv/PRX-type publications, 2023, 2023
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