Fano Effects In Transport Through A Coupling Quantum Wire-dot System

Fano effect is well known in optics and condensed matter communities. It arises from quantum interference between resonant and non-resonant paths. Quantum dot, especially coupled quantum dot structure, provides more than one path for electron's coherent tunneling, therefore one expects Fano effects in transport properties of quantum dot systems. The aim of this paper is to investigate Fano effect in transport through coupled quantum wire-dot systems. Using nonequilibrium Green's function formalism, we conduct a systematic investigation on Fano effects in two types of coupled quantum wire-dot structures. Based on the same Hamiltonian model, we explore Fano effects in transport through a quantum wire side-attached a two-level quantum dot and coupled quantum dots with two levels and one level. Our results demonstrate interesting resonant peak structures in linear conductance dip for a quantum wire side-attached a quantum dot. Such a phenomenon is a direct result of Fano interference. For the coupled quantum dot structure, the linear conductance exhibits interesting multiple resonant peaks. Destructive Fano interference leads to the appearance of two conductance dips, while three resonant peaks is due to resonant tunneling through the recombined three levels of the coupled quantum dot structure. The lineshape of conductance peak is not Lorenzian due to Fano interference.