AHARONOV–BOHM OSCILLATIONS AND FANO RESONANCE IN A MESOSCOPIC RING WITH A SIDE-COUPLED QUANTUM DOT

Abstract

We calculate the transmission coefficient through an Aharonov–Bohm ring with a multi-level quantum dot side-coupled to one arm. Whenever a quantum dot level is tuned across the Fermi energy, the coupled arm is blocked for electron tunneling, namely anti-resonance. This leads to the suppression of the Aharonov–Bohm oscillations, accompanied by a phase jump of π in the oscillations. The Aharonov–Bohm phase also changes sharply by π in between neighboring anti-resonances due to the multi-level effect. The transmission has an expression of the generalized Fano form with a complex Fano parameter q in the presence of the Aharonov–Bohm flux.