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TT: Fachverband Tiefe Temperaturen

TT 47: Correlated Electrons: Spin Systems and Itinerant Magnets - Frustrated Magnets III

TT 47.2: Vortrag

Dienstag, 1. April 2014, 14:15–14:30, HSZ 03

Spin-current autocorrelations from single pure-state propagation — •Robin Steinigeweg¹, Jochen Gemmer², and Wolfram Brenig¹ — ¹Institute for Theoretical Physics, Technical University Braunschweig, Germany — ²Department of Physics, University of Osnabrück, Germany

We study spin dynamics in the anisotropic and antiferromagnetic spin-1/2 Heisenberg chain in the long-wavelength limit. To this end, we numerically calculate the spin-current autocorrelation function by propagating only a single pure state in time, which is a “typical” representative of the quantum statistical ensemble. By comparing to short-time data from time-dependent density matrix renormalization group, we show that quantum typicality is fulfilled extremely well. This quantum typicality allows us to determine almost exactly the long-time Drude weight for chains as long as L=33 sites, i.e., with a 8192 × larger Hilbert space than the typically considered L ∼ 20 sites within the range of exact diagonalization. Therefore we can shed light on the Drude weight in the thermodynamic limit at both, high and low temperatures. Even though we apply our approach to an integrable quantum system in one dimension, it is applicable to non-integrable models in a much more general framework.