LAUSR

The braiding statistics of certain fractional quantum Hall states can be probed via interferometry of their edge states. Practical difficulties—including loss of phase coherence—make this a challenging task. We demonstrate the operation of a small Fabry–Perot interferometer in which highly coherent Aharonov–Bohm oscillations are observed in the integer and fractional quantum Hall regimes. Careful design of the heterostructure suppresses Coulomb effects and promotes strong phase coherence. We characterize the coherency of edge-mode interference by the energy scale for thermal damping and determine the velocities of the inner and outer edge modes independently via selective backscattering of edge modes originating in the N = 0, 1, 2 Landau levels. We also observe clear Aharonov–Bohm oscillations at fractional filling factors ν = 2/3 and ν = 1/3, which indicates that our device architecture provides a platform for measurement of anyonic braiding statistics.An interferometer device demonstrates the interference of fractional quantum Hall effect edge states. This is a big step towards braiding non-Abelian anyons.