"Correlating electrons and braiding anyons in graphene quantum Hall interferometers"
Two-dimensional electrons in large magnetic fields spontaneously form quantum Hall states, where injected current flows ballistically in chiral, one-dimensional edge states. At low temperatures, edge current coherence is maintained over long enough lengths (microns) that quantum interferometers can reveal the current-carrying quasiparticle’s phase. In fractional quantum Hall states, quasiparticles are expected to be anyons, with fractional charge and non-trivial braiding phase upon identical particle exchange, unlike fermions or bosons. In this talk, I will present experiments constructing edge state interferometers in graphene to probe fractional charge and anyon braiding phase in fractional quantum Hall states. I first demonstrate interference of electrons in integer quantum Hall states, revealing Aharonov-Bohm resistance oscillations [1]. Next, I uncover correlations between electrons in co-propagating integer edge states that lead to unexpected phase jumps and oscillation frequency doubling [2]. Finally, I present interference of fractional charges and observation of the anyon braiding phase in two fractional quantum Hall states [3]. These results demonstrate the potential of van der Waals materials for creating quantum coherent electronic devices and unveiling phenomena that are otherwise inaccessible via transport measurements.
[1] Y. Ronen, T. Werkmeister et al. Aharonov–Bohm effect in graphene-based Fabry–Pérot quantum Hall interferometers. Nature Nanotechnology 16, 563–569 (2021).
[2] T. Werkmeister et al. Strongly coupled edge states in a graphene quantum Hall interferometer. Nature Communications 15,6533(2024).
[3] T. Werkmeister, J.R. Ehrets et al. Anyon braiding and telegraph noise in a graphene interferometer. Science 388, 730–735 (2025).
