Quantum oscillations of the persistent current in a normal loop

A quantum two-level system based on the superposition of current states circulating in either the clockwise or counterclockwise direction is proposed. A one-dimensional ring with inhomogeneity in the on-site energies is shown to be suitable to exhibit such an effect. Quantum oscillations between two states can be observed by initialization of the system through a trapped magnetic field. We consider decoherence effects due to electron-phonon interaction and discuss possible effects derived from disorder. Finally, a possible application to carbon nanotubes is discussed.