Aharonov-Bohm oscillations of a tunable quantum ring
  With an atomic force microscope a ring geometry with self-aligned in-plane gates was directly written into a GaAs/AlGaAs-heterostructure. Transport measurements in the open regime show only one transmitting mode and Aharonov-Bohm oscillations with more than 50% modulation are observed in the conductance. The tuning via in-plane gates allows to study the Aharonov-Bohm effect in the whole range from the open ring to the Coulomb-blockade regime. 
U. F. Keyser, S. Borck, R. J. Haug, W. Wegscheider, M. Bichler, and G.   Abstreiter