•Björn Kubala¹, Jürgen König², Herbert Schoeller³ und Gerd Schön^1
1Institut für theoretische Festkörperphysik,Universitaet Karlsruhe, 76129 Karlsruhe, Germany
²Department of Physics, The University of Texas at Austin,Austin, TX 78712, USA
³Forschungszentrum Karlsruhe, Insitut für Nanotechnologie,76021 Karlsruhe, Germany

We investigate interference and interaction effects in two dots embedded in an Aharonov-Bohm geometry. We find that the total transmission through the system behaves qualitatively very different depending on the level positions in the two dots. Without interaction, the off resonance transmission (cotunneling) is twice the sum of the transmissions through the dots taken apart, while at resonance (sequential tunneling) no factor 2 is involved. We study the crossover between the two regimes and analyse the influence of intra- and inter-dot Coulomb repulsion.