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TT: Fachverband Tiefe Temperaturen
TT 4: Low-Dimensional Systems: 1D - Theory
TT 4.1: Vortrag
Montag, 31. März 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 Moore2 — 1Ludwig-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)