Conductance through a quantum dot in an Aharonov-Bohm ring

Using scattering theory and the multichannel Landauer-Buttiker formula we calculate the conductance of an Aharonov-Bohm (AB) ring with a quantum dot embedded in one of its arms. The electron-electron interaction within the dot is treated in a self-consistent mean-field approximation. An analytical expression is derived for the AB oscillations of the entire device. This expression displays explicitly the dependence on temperature and on the voltage applied to the dot. It is shown that the amplitude of the AB oscillations with period h/e vanishes close to a conductance resonance of the quantum dot. This leads to a sudden phase change by pi in these oscillations, in agreement with a recent experiment [Yacoby et al., Phys. Rev. Lett. 74, 4047 (1995)]. We also find that the total width and the partial width amplitudes of each conductance resonance are oscillatory functions of flux. This leads to oscillations in the excitation spectrum of the dot which may be observable in further experiments.