Transport through a Kondo quantum dot: Functional RG approach

We apply the functional renormalization group (FRG) method to calculate the conductance of a quantum dot in the Kondo regime. Starting from the exact FRG equations in Keldysh formulation for the Kondo exchange Hamiltonian in pseudo‐fermion (pf) representation, we solve the coupled equations for the pf self energy and the coupling function, neglecting three‐particle and higher correlation functions. The conductance G as a function of temperature T and bias voltage V is calculated using a renormalized Golden Rule expression. The limiting behavior at T and/or V >> TK (TK: Kondo temperature) agrees with known results. The difficulties when approaching strong coupling are analyzed and improvements are suggested.

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