Electron correlation resonances in the transport through a single quantum level

Correlation effects in the transport properties of a single quantum level coupled to electron reservoirs are discussed theoretically using nonequilibrium Green functions approach. Our method is based on the introduction of a second-order self-energy associated with the Coulomb interaction that consistently eliminates the pathologies of previous perturbative calculations. We present results for the current-voltage characteristic illustrating the different correlation effects that may be found in the system, including the Kondo anomaly and Coulomb blockage. We discuss the experimental conditions for the simultaneous observation of these effects in an ultrasmall quantum dot.