Energy spectra of quantum rings

摘要: High quality quantum rings are fabricated by nano-lithography with a scanning force microscope. The electron occupancy as well the tunneling contacts to source and drain controlled in-plane top gate voltages. Coulomb blockade oscillations in conductance through ring give information about energy spectrum wave functions. peak positions amplitudes oscillate periodically function of magnetic field. period is given an Aharonov-Bohm-type argument, i.e., one flux h/e area defined ring. Some states show pronounced zig-zag behavior field agreement perfect Other display rather flat dispersion. We argue that state depends on degree which its localized or extended along circumference around