Fermionic parity stability and interference measurements of non-Abelian e/4 and Abelian e/2 quasiparticle braiding at 7/2 and 5/2 filling factors*

The 5/2 state is expected to have Abelian charge e/2 quasiparticles and non-Abelian charge e/4 quasiparticles; past interference measurements are consistent with this [1]. Recent [2] interferometer experiments present 3 new findings: 1) at 5/2 four dominant resistance oscillation periods are observed at the expected values for the full complement of braids of non-Abelian e/4 and Abelian e/2: e/2 braiding e/2, e/4 braiding e/2, and modulated oscillations specifically attributable to non-Abelian e/4 braiding e/4, the even-odd effect. Parameters controlling expression of these oscillations are delineated. 2) at 7/2 this full complement of e/4 and e/2 braiding oscillations is also observed, but at different periods as expected for that filling factor. 3) most importantly, the oscillations attributable to non-Abelian e/4 even-odd effect are stable against fermionic parity fluctuations over long times (hours) near 5/2 and 7/2; this observed stability strengthens the case for using non-Abelian e/4 quasiparticles for topological quantum computation.
[1] PNAS 106, 8853; & PRL.111,186401.
[2] Interference measurements of non-Abelian e/4 and Abelian e/2 quasiparticle braiding, arXiv:1905.10248.