Observation of e/4 charge at ν=1/2 in GaAs

Even-denominator fractional quantum Hall states (FQHSs) fall outside the standard Laughlin's and Jain's odd-denominator hierarchy. In this work, we study the FQHS 𝜈 = 1/2 in the lowest Landau level. The state is confined within a 70 nm-wide GaAs quantum well, where the electrons exhibit a bilayer-like charge distribution. Inter-layer interactions stabilize the 𝜈 = 1/2 FQHS, which is predicted to host quasiparticles with charge e/4-with either Abelian or non-Abelian topological order. Here, we report on shot-noise measurements of partitioned quasiparticles at 𝜈 = 1/2, where charge partitioning is generated by a unique etch-defined quantum point contact. Our measurements were performed on two nominally identical devices, at two independent experimental setups. Analysis of shot noise in the weak-backscattering regime in each device reveals quasiparticles with charge e/4. These observations provide a clear benchmark for future studies aimed at probing the topological order of the 𝜈 = 1/2 FQHS and its quasiparticles' exchange statistics.