Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 96: Correlated Electrons: Nonequilibrium Quantum Many-Body Systems II

TT 96.2: Talk

Thursday, April 3, 2014, 15:15–15:30, HSZ 304

Stationary properties of generic 2-level systems in nonequilibrium — •Stefan Goettel, Frank Reininghaus, and Herbert Schoeller — Institut für Theorie der Statistischen Physik, RWTH Aachen

We consider a generic quantum dot in nonequilibrium in the Coulomb blockade regime at fixed charge and zero temperature. In the weak coupling regime, we present a generic weak-coupling expansion of the stationary density matrix and the conductance based on a recent formulation of real-time renormalization group (RTRG) by using the Laplace variable as flow parameter, in analogy to the expansion presented in Ref.[3] where a Masubara-frequency cutoff has been used. We apply this expansion to a 2-level system and find generically that the effective Liouvillian contains terms linear or quadratic in the renormalized couplings which can not be described by perturbation theory with renormalized couplings from poor man scaling methods. At large bias voltage, we find that at vanishing and large magnetic fields renormalized perturbation theory works well whereas at intermediate magnetic fields of the same order as the typical renormalization, significant differences occur which can only be described from the full RTRG method. Furthermore, we present evidence that the same generic behaviour is expected for 3- and 4-level systems.
M. Pletyukhov, H. Schoeller, Phys. Rev. Lett. 108, 260601 (2012)
O. Kashuba and H. Schoeller, Phys. Rev. B87, 201402(R) (2013)
H. Schoeller and F. Reininghaus, Phys. Rev. B80, 045117 (2009)