Abstract
Fractional quantum statistics are the defining characteristic of anyons. Measuring the phase generated by an exchange of anyons is challenging, as standard interferometry set-ups—such as the Fabry–Pérot interferometer—suffer from charging effects that obscure the interference signal. Here we present the observation of anyonic interference and exchange phases in an optical-like Mach–Zehnder interferometer based on co-propagating interface modes. By avoiding backscattering and deleterious charging effects, this set-up enables pristine and robust Aharonov–Bohm interference without any phase slips. At various fractional filling factors, the observed flux periodicities agree with the fundamental fractionally charged excitations that correspond to Jain states and depend only on the bulk topological order. To probe the anyonic statistics, we used a small, charged top gate in the interferometer bulk to induce localized quasiparticles without modifying the Aharonov–Bohm phase. The added quasiparticles introduce periodic phase slips. The sign and magnitude of the observed phase slips align with the expected value at filling 1/3, but their direction shows systematic deviations at fillings 2/5 and 3/7. Control over added individual quasiparticles in this design is essential for measuring the coveted non-abelian statistics in the future.
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Data availability
Source data are provided with this paper. These data are also publicly available via Zenodo at https://doi.org/10.5281/zenodo.15394075(ref. 42).
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Acknowledgements
M.H. thanks D. E. Feldman for fruitful discussions and M. Banerjee for her suggestions. B.G and M.L thanks A. K. Paul, H. K. Kundu and S. Biswas for the helpful comments that improved our device. B.G. and M.L. thank A. Gupta for help with the statistical phase analysis. D.F.M. acknowledges many illuminating conversations on quantum Hall interferometry with Y. Ronen. D.F.M. was supported by the Israel Science Foundation (grant no. 2572/21) and by the Deutsche Forschungsgemeinschaft within the CRC network TR 183 (project grant no. 277101999). M.H. acknowledges the support of the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 833078). M.L. thanks the Ariane de Rothschild Women Doctoral Program for their support.
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B.G. fabricated the devices. B.G. and M.L. performed the measurements and analysed the data with input from M.H. L.M. characterized the devices at the initial stage of the experiment. M.H. supervised the experimental design, execution and data analysis. D.F.M. worked on the theoretical aspects and data analysis. V.U. grew the GaAs heterostructures. All authors contributed to the writing of the paper.
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Source Data Fig. 1 Raw data for Fig. 1d. Source Data Fig. 2 Raw data without background subtraction. Source Data Fig. 3 Raw data for each panel without background subtraction. Source Data Fig. 4 Raw data for each panel without background subtraction. Figure 4b,d were obtained from line cuts of Fig. 4a,c so source data are not provided.
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Ghosh, B., Labendik, M., Musina, L. et al. Anyonic braiding in a chiral Mach–Zehnder interferometer. Nat. Phys. (2025). https://doi.org/10.1038/s41567-025-02960-3
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DOI: https://doi.org/10.1038/s41567-025-02960-3
