Kondo Correlations and the Fano Effect in Closed AB-Interferometers

Abstract

We study the Fano-Kondo effect in a closed Aharonov-Bohm (AB) interferometer which contains a single-level quantum dot and predict a frequency doubling of the AB oscillations as a signature of Kondo-correlated states. Using Keldysh formalism, Friedel sum rule and Numerical Renormalization Group, we calculate the exact zero-temperature linear conductance $G$ as a function of AB phase $ϕ$ and level position $ε$. In the unitary limit, $G(ϕ)$ reaches its maximum $2e^2/h$ at $ϕ=π/2$. We find a Fano-suppressed Kondo plateau for $G(ε)$ similar to recent experiments.

4 pages, 4 eps figures