Electron interactions in an antidot in the integer quantum Hall regime

A quantum antidot, a submicron depletion region in a two-dimensional electron system, has been actively studied in the past two decades, providing a powerful tool for understanding quantum Hall systems. In a perpendicular magnetic field, electrons form bound states around the antidot. Aharonov-Bohm resonances through such bound states have been experimentally studied, showing interesting phenomena such as Coulomb charging, h/2e oscillations, spectator modes, signatures of electron interactions in the line shape, Kondo effect, etc. None of them can be explained by a simple noninteracting electron approach. Theoretical models for the above observations have been developed recently, such as a capacitive-interaction model for explaining the h/2e oscillations and the Kondo effect, numerical prediction of a hole maximum-density-droplet antidot ground state, and spin density-functional theory for investigating the compressibility of antidot edges. In this review, we summarize such experimental and theoretical works on electron interactions in antidots.