Universal out-of-equilibrium transport in Kondo-correlated quantum dots: a renormalized superperturbation theory on the Keldysh contour

The non-linear conductance of semiconductor heterostructures and single molecule devices exhibiting Kondo physics has recently attracted attention [1,2]. We address the observed sample-dependence across various systems by considering additional electronic contributions present in the effective low-energy model underlying these experiments. To this end we develop a novel version of the superperturbation theory [3] in terms of dual fermions on the Keldysh contour. We analyze the role of particle hole asymmetry on the transport coefficients. Our approach [4] systematically extends the work of Yamada and Yosida and others to the particle-hole asymmetric Anderson model and reproduce the exactly solvable resonant level model and the special case considered in [5]. It correctly describes the strong coupling physics and is free of internal inconsistencies that would lead to a breakdown of current conservation. \\[4pt] [1] M. Grobis et al., Phys. Rev. Lett. 100, 246601 (2008).\\[0pt] [2] G. D. Scott et al., Phys. Rev. B 79, 165413 (2009).\\[0pt] [3] H. Hafermann et al., EPL 85, 27007 (2009).\\[0pt] [4] Enrique Munoz, C.J. Bolech, and Stefan Kirchner, submitted (2011).\\[0pt] [5] K. Yamada, Prog. Theo. Phys. 62, 354 (1979).