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TT: Tiefe Temperaturen
TT 4: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 4.2: Talk
Monday, March 27, 2006, 11:30–11:45, HSZ 301
Real Time RG for the non-equilibrium Kondo model: Cutoffs set by voltage and decoherence. — •Thomas Korb1, Herbert Schoeller1, and Jürgen König2 — 1Theoretische Physik A, RWTH Aachen, Germany — 2Theoretische Physik III, Ruhr-Universität Bochum
While the equilibrium Kondo effect is well understood there is known less for the Kondo effect in non-equilibrium. The question was raised, if a finite voltage and current induced decoherence prevents the system from going into the strong coupling limit for V>TK and how to calculate the I-V [1,2]. In [2] a perturbative RG for the scaling of the verticies in non-equilibrium was developed, but the decoherence was included only on the basis of a perturbation calculation. A different approach was used in [3], where a flow equation analysis was performed on the expense to reside on a Hamiltonian description for the non-equilibrium. There it was found, that the scaling is cutted by balancing of second and third order contributions in the flow equations. We use the real time RG formalism developed in [4] to analyze the non-equilibrium Kondo effect. It is demonstrated how the cutoffs set by voltage and decoherence rate emerge naturally from a closed set of RG equations on the Keldysh contour (including dephasing of nondiagonal elements of the density matrix). Therefore we are able to calculate the I-V characteristic for V>TK within one scheme and within a full nonequilibrium formalism.
[1] P. Coleman et al., Phys. Rev. Lett. 86, 4088 (2001).
[2] A. Rosch et al., Phys. Rev. Lett. 90, 076804 (2003).
[3] S. Kehrein, Phys. Rev. Lett. 95, 056602 (2005).
[4] H. Schoeller and J. König, Phys. Rev. Lett. 84, 3686 (2000).