Characteristics of resonance signals in mesoscopic systems with coulomb interaction

Abstract

In this dissertation, we theoretically study some characteristic features of resonance signals in mesoscopic electron systems with Coulomb interaction. Specifically, three kinds of systems are investigated. First, we study Fano resonance in a two-level quantum dot side-coupled to two leads which are connected by a direct channel. Above Kondo temperature, the Fano resonance line shape in conductance signals is found to be deformed, from the conventional single-level Fano form, by interlevel Coulomb interaction and interlevel interference. The line-shape deformation is connected to the interaction-induced nonmonotonicity of level occupation. Below Kondo temperature, it is found that Kondo effect is very sensitive to the direct channel coupling. Second, we analyze recent experimental data on excitonic Fano resonance in semiconductor superlattices biased by an external electricfield. The Fano resonance line shape in absorption spectra shows anomalous parabolic dependence on the field strength, which is attributed to the non-uniform densities of the continuum states tuned by the electric field. Finally, we study some intriguing patterns of Aharonov-Bohm resonance in antidot systems with multiple modes in the integer quantum Hall regime. We find that mutual capacitive interactions between the bound states can make some resonant states energetically unfavorable, leading to no contribution of the states in conductance signals. Such spectator behavior highly depends on the geometric properties of the systems.