1110.6610 (Robin Steinigeweg)

Spin transport in the XXZ model at high temperatures: Classical dynamics
versus quantum S=1/2 autocorrelations    [PDF]

Robin Steinigeweg

The transport of magnetization is analyzed for the classical Heisenberg chain
at and especially above the isotropic point. To this end, the Hamiltonian
equations of motion are solved numerically for initial states realizing
harmonic-like magnetization profiles of small amplitude and with random phases.
Above the isotropic point, the resulting dynamics is observed to be diffusive
in a hydrodynamic regime starting at comparatively small times and wave
lengths. In particular, hydrodynamic regime and diffusion constant are both
found to be in quantitative agreement with close-to-equilibrium results from
quantum S=1/2 autocorrelations at high temperatures. At the isotropic point,
the resulting dynamics turns out to be non-diffusive at the considered times
and wave lengths.

View original: http://arxiv.org/abs/1110.6610