Aharonov–Bohm interference in even-denominator fractional quantum Hall states

Position exchange of non-Abelian anyons affects the quantum state of their system in a topologically protected way1. Their expected manifestations in even-denominator fractional quantum Hall (FQH) systems offer the opportunity to directly study their unique statistical properties in interference experiments2. Here we present the observation of coherent Aharonov–Bohm interference at two even-denominator states in high-mobility bilayer-graphene-based van der Waals (vdW) heterostructures by using the Fabry–Pérot interferometry technique. Operating the interferometer at a constant filling factor, we observe an oscillation period corresponding to two flux quanta inside the interference loop, ΔΦ = 2Φ0, at which the interference does not carry signatures of non-Abelian statistics. The absence of the expected periodicity of ΔΦ = 4Φ0 may indicate that the interfering quasiparticles carry the charge $${e}^{* }=\frac{1}{2}e$$or that interference of $${e}^{* }=\frac{1}{4}e$$quasiparticles is thermally smeared. Notably, at two hole-conjugate states, we also observe oscillation periods of half the expected value, indicating interference of $${e}^{* }=\frac{2}{3}e$$quasiparticles instead of $${e}^{* }=\frac{1}{3}e$$. To investigate statistical phase contributions, we operated the Fabry–Pérot interferometer (FPI) with controlled deviations of the filling factor, thereby introducing fractional quasiparticles inside the interference loop. The resulting changes to the interference patterns at both half-filled states indicate that the extra bulk quasiparticles carry the fundamental charge $${e}^{* }=\frac{1}{4}e$$, as expected for non-Abelian anyons.