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Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 4: Low-Dimensional Systems: 1D - Theory

TT 4.1: Talk

Monday, March 31, 2014, 09:45–10:00, HSZ 201

Diffusive and ballistic dynamics in local quenches in 1D spin-1/2 systems at finite temperatures — •Fabian Heidrich-Meisner1, Christoph Karrasch2, and Joel Moore21Ludwig-Maximilians-University Munich — 2University of California, Berkeley

We study the spreading of local perturbations in the spin and energy density of spin-1/2 systems at finite temperatures [1], using the time-dependent density matrix renormalization group technique. In the integrable XXZ chain, we observe a ballistic dynamics of energy at all temperatures and for all exchange anisotropies. The spin dynamics, by contrast, is diffusive in the Ising phase at high temperatures. We extract the diffusion constant from these local quenches at infinite temperatures and show that the values are in quantitative agreement with the Einstein relation for sufficiently small local perturbations. We also study spin ladder systems, for which we observe examples of diffusive spin and energy dynamics at finite temperatures. The connection of our results to recent experiments with cold gases [2] and quantum magnets [3] is discussed.
C. Karrasch, J. Moore, F. Heidrich-Meisner, in preparation.
J.P. Ronzheimer et al., Phys. Rev. Lett. 110, 205301 (2013)
M. Montagnese et al., Phys. Rev. Lett. 110, 147206 (2013)

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