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TT: Fachverband Tiefe Temperaturen
TT 19: Correlated Electrons: Nonequilibrium Quantum Many-Body Systems 2 (jointly with DY)
TT 19.5: Vortrag
Montag, 16. März 2015, 16:00–16:15, H 3010
Real-time dynamics of energy currents in perturbed Heisenberg spin-1/2 chains — •Robin Steinigeweg1, Jacek Herbrych2, Jochen Gemmer3, and Wolfram Brenig1 — 1Institute for Theoretical Physics, Technical University Braunschweig, Germany — 2CCQCN, University of Crete, Greece — 3Department of Physics, University Osnabrück, Germany
We use the concept of typicality to study the real-time dynamics of energy currents in nonintegrable spin-1/2 models in one dimension and at nonzero temperatures. These models are perturbed XXZ chains, where the integrability-breaking perturbation is either a staggered magnetic field or a complex exchange-coupling structure. Within linear response theory, we numerically calculate autocorrelation functions by propagating a single pure state, drawn at random as a typical representative of the full statistical ensemble. By comparing to small-system data from exact diagonalization and existing data from tDMRG, we show that typicality is satisfied in finite systems over a wide temperature range and valid in both, integrable and nonintegrable systems. We also confirm the validity of our approach by comparing to spectra from Lanczos diagonalization. For the large system sizes treatable, we observe little finite-size effects for large and small perturbation strengths. This allows us to obtain the full relaxation curve of the energy current and to determine the scaling of the heat conductivity.
[1] R. Steinigeweg, J. Gemmer, W. Brenig, PRL 112, 120601 (2014).
[2] R. Steinigeweg, J. Gemmer, W. Brenig, arXiv:1408.6837 (2014).
[3] R. Steinigeweg, J. Herbrych, W. Brenig, in preparation.