Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 15: Dual-Method Approaches to Quantum Many-Body Systems I
TT 15.12: Vortrag
Montag, 12. März 2018, 18:00–18:15, H 0104
Functional Renormalization Group Approach to Transport through a Kondo Quantum Dot — •Jan Diekmann and Severin G. Jakobs — Institute for Theory of Statistical Physics, RWTH Aachen University, 52056 Aachen, Germany
We study nonequilibrium properties of the Kondo model. For this we use the 1PI functional renormalization group (fRG), and work in Keldysh formalism. We choose a drone-fermion representation for the impurity spin.
As a first step we reproduce the leading logarithmic approximation in the weak-coupling regime (T≫ TK) known as Poor Man’s Scaling (PMS), which is an equilibrium result. Within fRG the employed approximation scheme emerges in a very natural way, and a clear interpretation of the flowing quantities is given as amplitudes of the renormalized 1PI vertex functions.
We devise a more sophisticated fRG approximation scheme as a direct extension of the one used to reproduce the PMS result. In particular we take frequency dependence and the self energy of the spin back into account. With this we seek to describe the nonequilibrium case and to check whether the approach is suitable to describe the crossover to the strong-coupling regime.
A long term goal is to investigate the relation between different RG approaches to the nonequilibrium Kondo problem.