Transport in Multilevel Quantum Dots: From the Kondo Effect to the Coulomb Blockade Regime

A new theoretical method is introduced to study coherent electron transport in an interacting multilevel quantum dot. The method yields the correct behavior in the limit of both weak and strong coupling to the leads, giving a unified description of the Coulomb blockade and the Kondo effect. Results for the density of states and the temperature-dependent conductance for a two-level dot are presented. The relevance of these results in connection to recent experiments on the Kondo effect in semiconducting quantum dots is discussed.