Quenched Kondo resonance in a quantum dot induced by the presence of an Anderson impurity in the conduction electron reservoir

For a quantum dot (QD) in the Kondo regime, we introduce a side QD attached to one of the two leads to mimic an Anderson impurity in the conduction electron reservoir. Then, we study the peculiar Kondo effect in such a double QD structure. We find that the Kondo peak in the local density of states in the QDs exhibits a notable deviation from the Lorentzian line shape. More importantly, the expected Kondo peak in the linear conductance turns into zero when a Kondo level or a single-particle level of the side QD is aligned with the Fermi level. This result indicates that the presence of an Anderson impurity in the leads can quench the electron transport through the central QD. The underlying mechanism to cause this behavior is ascribed to quantum interference, which is clearly described in the language of Feynman paths.