Aharonov–Bohm effect in graphene-based Fabry–Pérot quantum Hall interferometers

Abstract

Quantum interferometers are powerful tools for probing the wave-nature and exchange statistics of indistinguishable particles. Of particular interest are interferometers formed by the chiral, onedimensional (1D) edge channels of the quantum Hall effect (QHE) that guide electrons without dissipation. Using quantum point contacts (QPCs) as beamsplitters, these 1D channels can be split and recombined, enabling interference of charged particles. Such quantum Hall interferometers (QHIs) can be used for studying exchange statistics of anyonic quasiparticles. In this study we develop a robust QHI fabrication technique in van der Waals (vdW) materials and realize a graphene-based Fabry-Pérot (FP) QHI. By careful heterostructure design, we are able to measure pure Aharonov-Bohm (AB) interference effect in the integer QHE, a major technical challenge in finite size FP interferometers. We find that integer edge modes exhibit high visibility interference due to relatively large velocities and long phase coherence lengths. Our QHI with tunable QPCs presents a versatile platform for interferometer studies in vdW materials and enables future experiments in the fractional QHE.

A tunable Fabry–Pérot quantum Hall interferometer in graphene

“…The high-visibility Aharonov-Bohm interference that we observe with excellent agreement with the non-interacting theory 4 demonstrates the relevance of graphene for performing prototypical QH-FP interferometry with integer quantum Hall edge channels. The high mobility and the versatility of the graphene van der Waals hetereostructures turn out to be pivotal to harness fine control of QH edge-channel transmissions in QPCs 41 , and therefore construct advanced gate-tunable interferometers, as also confirmed in similar devices recently 44 . With further study in the fractional quantum Hall regime, this graphene platform gives new opportunities for anyon physics in QH interferometers, potentially extendable to time-resolved electron quantum optics experiments 3 .…”

Vanishing Thermal Equilibration for Hole-Conjugate Fractional Quantum Hall States in Graphene

“…The region Δ close to 1 corresponds to very strong interactions. We argue that the sharp confining potential of our graphene devices, where the screening graphite gate is separated from the electron gas of graphene by a thin insulating h-BN layer (∼10-20 nm) [13,14,44,45], favors this regime in contrast to the shallow confining potential in GaAs/AlGaAs devices [5,6]. For l C eq , the smallness of the tunneling current is compensated by the smallness of the charge conductance of one of the eigenmodes (g − ).…”

Conductance oscillation in surface junctions of Weyl semimetals

“…Therefore, high-quality contacts are required for the observation of the conductance oscillation. Good contacts with smooth boundaries can be implemented by state-of-the-art fabrication techniques [66], like electronbeam lithography [69,70]. For example, the length of the electrodes along the smooth boundary can reach 4 μm [66], whereas the Fermi wavelength of the WSM in our system is boundaries are smooth enough, then the transverse momentum k z is approximately conserved during scattering.…”