Interference and interaction effects in multi-level 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 $ϕ$, we find a large direct tunnel splitting $|Δ|\sim (Γ/π)|\cos(ϕ/2)|\ln(U/ω_c)$ between the levels of the order of the level broadening $Γ$. As a consequence we discover a many-body resonance in the spectral density that can be measured via the absorption power. Furthermore, for $ϕ=π$, we show that the system can be tuned into an effective Anderson model with spin-dependent tunneling.