Fano Resonance in Transport Through Double Quantum Dot in Parallel

The transport properties of double quantum dot (DQD) in parallel are theoretically examined. This system simulates a mesoscopic ring with an embedded quantum dot, so-called Aharonov–Bohm (AB) interferometer, by enlarging the line width in one of the quantum dots. We find that: 1) the Coulomb peak shows an asymmetric shape of Fano resonance when the DQD is coupled to external leads with single conduction channel; 2) the peak becomes more symmetric for the leads with multiple channels; and 3) the resonant shape is characterized by a single parameter which is determined by the structure of the leads. Our theory may explain the experimental results on the transport through the AB interferometer; an asymmetric Fano resonance was observed by one group while a symmetric Breit–Wigner resonance was observed by the other groups.