Decoherence and current fluctuations in tunneling through coupled quantum dots

The electronic transport through two coupled quantum dots in series can be described either in a fully coherent approach (e.g. density matrix description or nonequilibrium Green's functions) or in a simple sequential tunneling treatment (Pauli master equation with Fermi's Golden rule for coupling between the quantum dots). It turns out that both descriptions provide the same average current for noninteracting electrons. In contrast, the zero-frequency spectral power density and the skewness are different for intermediate coupling strengths between the quantum dots reflecting their sensitivity on coherence in the tunneling process.