Kondo resonances and Fano antiresonances in transport through quantum dots

The transmission of electrons through a noninteracting tight-binding chain with an interacting side quantum dot (QD) is analyzed. When the Kondo effect develops at the dot the conductance presents a wide minimum, reaching zero at the unitary limit. This result is compared to the opposite behavior found in an embedded QD. Application of a magnetic field destroys the Kondo effect and the conductance shows pairs of dips separated by the charging energy U. The results are discussed in terms of Fano antiresonances and explain qualitatively recent experimental results.