Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 55: Focus: Emergent phenomena in driven quantum many-body systems (joint session DY/TT)

DY 55.3: Vortrag

Donnerstag, 15. März 2018, 10:30–10:45, EB 107

Transient dynamics in an excitonic insulator: Fast computation of nonequilibrium Green's functions — •Riku Tuovinen1, Denis Golež2, Michael Schüler2, Martin Eckstein3, and Michael Sentef11Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany — 2Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland — 3Department of Physics, University of Erlangen-Nürnberg, 91058 Erlangen, Germany

A standard approach to nonequilibrium many-body problems is the Keldysh Green's function technique [1]. Information about the studied system, e.g. photoemission spectra etc., is encoded into the Green's function. To access this, we have to consider coupled integro-differential equations (Kadanoff-Baym equations), whose efficient solution is not trivial [2]. The Generalized Kadanoff-Baym Ansatz (GKBA) offers a simplification by decomposing the two-time-propagation of the Green's function into the time-propagation of a time-local density matrix [3]. We discuss the time-propagation method à la GKBA and present some benchmark simulations against the full solution of the Kadanoff-Baym equations, concentrating on a simple model for an excitonic insulator [4]. We investigate the dynamics of competing orders and how the balance between them could be controlled by laser driving.

[1] G. Stefanucci and R. van Leeuwen, Nonequilibrium many-body theory of quantum systems, CUP (2013) [2] A. Stan et al., J. Chem. Phys. 130, 224101 (2009) [3] P. Lipavský et al., Phys. Rev. B 34, 6933 (1986) [4] D. Golež et al., Phys. Rev. B 94, 035121 (2016)

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