•Daniel Boese^1,2, Walter Hofstetter³ und Herbert Schoeller^2,1
2Forschungszentrum Karlsruhe, Inst. für Nanotechnologie
³Theo. Physik III, Institut für Physik, Univ. Augsburg
¹Inst. für Theo. Festkörperphysik, Univ. Karlsruhe

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 f, we find a large direct tunnel splitting |D| ~ (G/p)cos²(f/2)ln(U/w_c) between the levels of the order of the level broadening G. As a consequence we discover a many-body resonance in the spectral density which can be measured via the absorption power. Furthermore, we show that the system can be tuned into an effective Kondo model by changing the Aharonov-Bohm phase to f = p.