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TT: Fachverband Tiefe Temperaturen

TT 83: Correlated Electrons: Nonequilibrium Quantum Many-Body Systems I

TT 83.12: Vortrag

Donnerstag, 3. April 2014, 12:45–13:00, HSZ 03

Auxiliary Hamiltonian representation of the nonequilibrium Dyson equation — •Karsten Balzer and Martin Eckstein — Max Planck Research Department for Structural Dynamics, University of Hamburg (CFEL), Building 99, Luruper Chaussee 149, 22761 Hamburg, Germany

The nonequilibrium Dyson (or Kadanoff-Baym) equation, which is an equation of motion with long-range memory kernel for real-time Green functions, underlies many numerical approaches based on the Keldysh formalism. We show how the problem of solving the Dyson equation in real-time can be mapped onto a noninteracting auxiliary Hamiltonian with additional bath degrees of freedom [1]. The solution of the auxiliary model does not require the evaluation of a memory kernel and can thus be implemented in a very memory efficient way. The mapping is derived for a self-energy which is local in space and is thus directly applicable within nonequilibrium dynamical mean-field theory (DMFT) [2]. We apply the method to study the interaction quench in the Hubbard model for an optical lattice with a narrow confinement, using inhomogeneous DMFT in combination with second-order weak-coupling perturbation theory. We find that, although the quench excites pronounced density oscillations, signatures of the two-stage relaxation similar to the homogeneous system can be observed by looking at the time-dependent occupations of natural orbitals.
C. Gramsch, K. Balzer, M. Eckstein and M. Kollar, Phys. Rev. B, accepted (2013) [arXiv:1306.6315]
H. Aoki, N. Tsuji, M. Eckstein, M. Kollar, T. Oka and P. Werner (2013) [arXiv:1310.5329]