Kondo correlations and the Fano effect in closed Aharonov-Bohm interferometers - art. no. 156803

We study the Fano-Kondo effect in a closed Aharonov-Bohm (AB) interferomete r which contains a single-level quantum dot and predict a frequency doublin g of the AB oscillations as a signature of Kondo-correlated states. Using t he Keldysh formalism, the Friedel sum rule, and the numerical renormalizati on group, we calculate the exact zero-temperature linear conductance G as a function of the AB phase phi and level position epsilon. In the unitary li mit, G(phi) reaches its maximum 2e(2)/h at phi = pi /2. We find a Fano-supp ressed Kondo plateau for G(epsilon) similar to recent experiments.