Coherent transport through a quantum dot embedded in an Aharonov-Bohm ring

We study the coherent transport in a multiterminal mesoscopic Aharonov-Bohm ring with a quantum dot embedded in an arm. Employing the Friedel sum rule for the effective single-particle levels in the quantum dot, we explain some anomalous features that have been observed in the experiment. We attribute these anomalies to the result of nontrivial quantum interference of the quantum dot with the attached ring. Further, we propose an anomalous feature of conductance oscillations, which can be a test for the validity of our model.