Charge-Kondo effect mediated by repulsive interactions

Abstract

We investigate the Kondo effect in a double-quantum-dot which is capacitively coupled to a charge-Qubit. It is shown that due to this capacitive coupling, the bare inter-dot repulsive interaction in the double-quantum-dot is effectively reduced and eventually changed to an attractive interaction for strong couplings between the double-quantum-dot and the Qubit. By deriving the low-energy effective Hamiltonian of the system, we find that the low energy dynamics of the system corresponding to these two positive or negative effective interaction regimes can be described, respectively, by an isotropic orbital-Kondo or an anisotropic charge-Kondo Hamiltonian. Moreover, we study various thermodynamic and electronic transport properties of the system by using the numerical renormalization group method.