Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 79: Correlated Electrons - Poster Session

TT 79.62: Poster

Mittwoch, 2. April 2014, 15:00–19:00, P2

Generalization of the Time-Dependent Numerical Renormalization Group Method to Finite Temperatures and General Pulses — •Hoa Nghiem and Theodoulos A. Costi — Peter Grünberg Institut and Institute for Advanced Simulation, Research Centre Jülich, 52425 Jülich, Germany

We generalize the time-dependent numerical renormalization group method (td-NRG)[1] to study the time evolution of an observable of an interacting quantum impurity system after a sudden quench at an arbitrary temperature without truncating the length of the Wilson chain [2]. This generalization requires the use of the full density matrix [3], and determining all the terms of the projected density matrix appearing in the time evolution. To evaluate these terms, we introduce efficient recursion relations. The numerical results are shown to be exact in the short time limit, while, in the long time limit, they strongly depend on the discretization parameter of NRG. We also consider the time evolution due to general continuous pulses, acting in a finite time interval. The calculation is done by discretizing the pulse into a sequence of small quenches, and generalizing the td-NRG to an arbitrary number of quenches.

[1] F. B. Anders and A. Schiller, Phys. Rev. Lett. 95, 196801 (2005).

[2] H. Nghiem and T. A. Costi, Preprint (2013).

[3] A. Weichselbaum and J. von Delft, Phys. Rev. Lett. 99, 076402 (2007).