Interference and interaction effects in multi-level quantum dots
  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 $\phi$, we find a large direct tunnel splitting $|\Delta|\sim (\Gamma/\pi)|\cos(\phi/2)|\ln(U/\omega_c)$ between the levels of the order of the level broadening $\Gamma$. As a consequence we discover a many-body resonance in the spectral density that can be measured via the absorption power. Furthermore, for $\phi=\pi$, we show that the system can be tuned into an effective Anderson model with spin-dependent tunneling. 
Daniel Boese (1,2), Walter Hofstetter (3), and Herbert Schoeller (2,1)   ((1) TFP U Karlsruhe, (2) FZ Karlsruhe INT, (3) U A...