Anyonic Braiding in a Chiral Mach-Zehnder Interferometer

Fractional quantum statistics are the defining characteristic of anyonic quantum states. Here, we present the observation of Anyonic interference and exchange phases in a novel co-propagating , 'optical-like,' Mach-Zehnder Interferometer (OMZI). Based on co-propagating interface modes , this architecture avoids backscattering and is free of charging effects that often plague the Fabry-Perot interferometer. Consequently, it exhibits a pristine and robust Aharonov-Bohm (AB) interference. At the filling factors ν = 1/3, 2/5, and 3/7, the observed AB flux periodicities: 3Φ ₀ , 5Φ ₀ , and 7Φ ₀ , (Φ ₀  =  h / e the flux quantum), agree with the fundamental fractionally charged excitations that correspond to Jain states. These flux periodicities depended only on the bulk topological order and not on the variety of tested interface modes for each bulk filling. To probe the Anyonic statistics, we positioned a small charged ‘top gate’ at the interferometer's center, allowing localized quasiparticles to be induced locally without modifying the AB phase of the interferometer. Being spatially isolated from the OMZI edge states, the observed quantized phase slips in the AB pajamas are purely quantum statistical effect. The magnitude of each phase slip corresponds to adding a fractional quasiparticle under the top gate. For ν = 1/3, their signs match theoretical expectations and prior FPI experiments, yet we observe systematic and unexpected deviations in the direction at ν = 2/5 and 3/7. The control over individual quasiparticles in this novel design will be essential for measuring the coveted non-Abelian statistics in the future.