Interference and interaction effects in multilevel quantum dots

Abstract

Using renormalization group techniques, we study spectral and transport properties of a spinless interacting quantum dot consisting of two levels coupled to metallic reservoirs. For strong Coulomb repulsion U and an applied Aharonov-Bohm phase $\ensuremath{\varphi},$ we find a large direct tunnel splitting $|\ensuremath{\Delta}|\ensuremath{\sim}(\ensuremath{\Gamma}/\ensuremath{\pi})|\mathrm{cos}(\ensuremath{\varphi}/2)|\mathrm{ln}(U/{\ensuremath{\omega}}_{c})$ between the levels of the order of the level broadening $\ensuremath{\Gamma}.$ As a consequence we discover a many-body resonance in the spectral density that can be measured via the absorption power. Furthermore, for $\ensuremath{\varphi}=\ensuremath{\pi},$ we show that the system can be tuned into an effective Anderson model with spin-dependent tunneling.