Single and double quantum Hall dots in monolayer graphene

Trapping individual quasiparticles in the quantum Hall regime offers a powerful route to directly probe their underlying exchange statistics. Here, we use dual-gated monolayer graphene to create and study single- and double quantum Hall dot devices. Our device geometry features a top gate patterned by atomic force microscope local anodic oxidation into a quantum point contact geometry containing a central hole of 70 nm in diameter. At moderate magnetic fields below 5 T, we observe single-electron charging event controlled by the displacement field in the hole region. Bias spectroscopy reveals a charging energy of approximately 1 meV, and the magnetic-field dependence is consistent with an antidot of about 80 nm in diameter. At higher magnetic fields, edge reconstruction leads to the formation of a double quantum dot, with a tunable interdot coupling controlled by displacement field. Our interpretation is supported by self-consistent Thomas–Fermi calculations.