Side-gate controlled graphene quantum Hall point contacts and interferometer

The vanishing band gap of graphene has long presented challenges for fabricating high-quality quantum point contacts (QPCs) -- the partially transparent p-n interfaces introduced by conventional split-gates tend to short the QPCs. This complication has hindered the fabrication of high-quality graphene quantum Hall Fabry-P\'erot interferometers, until recently split-gate QPCs operating in the symmetry-breaking regime have been successfully introduced. In contrast to this top-gated geometry, here we present a simple recipe to fabricate QPCs by etching a narrow trench in the graphene sheet to separate the conducting channel from self-aligned graphene side gates. We demonstrate QPC operation in a wide range of magnetic fields and further utilize this technique to study the Aharonov-Bohm interference in a quantum Hall interferometer.