A tunable Fabry-Perot quantum Hall interferometer in graphene

Electron interferometry with quantum Hall (QH) edge channels in semiconductor heterostructures can probe and harness the exchange statistics of anyonic excitations. However, the charging effects present in semiconductors often obscure the Aharonov-Bohm interference in QH interferometers and make advanced charge-screening strategies necessary. Here we show that high-mobility monolayer graphene constitutes an alternative material system, not affected by charging effects, for performing Fabry-Perot QH interferometry in the integer QH regime. In devices equipped with gate-tunable quantum point contacts acting on the edge channels of the zeroth Landau level, we observe-in agreement with theory-high-visibility Aharonov-Bohm interference widely tunable through electrostatic gating or magnetic fields. A coherence length of 10 mu m at a temperature of 0.02 K allows us to further achieve coherently coupled double Fabry-Perot interferometry. In future, QH interferometry with graphene devices may enable investigations of anyonic excitations in fractional QH states. Similar to optical waves, electrons can also interfere, but they require high-quality devices with minimal scattering for an experimental observation of this effect. An interferometer based on a single sheet of graphene provides an alternative to the more standard semiconductor devices and may in future enable access to exotic quantum effects, such as anyon braiding.

Automated summary

This study demonstrates high-mobility monolayer graphene as an alternative material system for Fabry-Perot quantum Hall interference in the integer quantum Hall regime, allowing for high-visibility Aharonov-Bohm interference tunable through electrostatic gating or magnetic fields. The coherence length of graphene devices at low temperatures enables coherently coupled double Fabry-Perot interferometry and potential investigations into anyonic excitations in fractional quantum Hall states in the future.