Theory of Fano effects in an Aharonov-Bohm ring with a quantum dot

Using a realistic model of a quantum dot embedded in an Aharonov-Bohm ring with several current-carrying channels, we demonstrate phase persistence in the Fano and Aharonov-Bohm effects as has been observed in experiments. The phase persistence arises because most of the states contributing to the Coulomb oscillation of the conductance are weakly coupled to ring states through a small number of states giving a major contribution to the conductance under off-resonant conditions.