Nonequilibrium theory for a quantum dot with arbitrary on-site correlation strength coupled to leads

An analytical expression for the current through a single level quantum dot for arbitrary strength of the on-site electron-electron interaction is derived beyond mean-field theory. By describing the localized states in terms of many-body operators, the employed diagrammatic technique for strong coupling between localized and delocalized states enables inclusion of electron correlation effects into the description of the local dynamics, which provides transport properties that are consistent with recent experimental data.