|
We investigate the real-time dynamics of the energy density in
spin-1/2 chains and ladders, starting from initial states with an
inhomogeneous profile of bond energies, extending our
previous work on the dynamics of spin-density wave packets [1].
These simulations are carried out using the adaptive
time-dependent density matrix renormalization group algorithm. We
analyze the time-dependence of the spatial variance of the bond
energies which yields necessary criteria for ballistic or
diffusive energy dynamics. In the case of the XXZ chain, our
results are consistent with ballistic behavior, both in the
massless and the massive phase. For the massless regime, we
compare our numerical results to predictions from bosonization
for, e.g., the velocity that the initial perturbation spreads
with. In the case of ladders, we find an involved dynamics whose
qualitative interpretation is still under scrutiny.
[1] Langer et al. Phys. Rev. B 79, 214409 (2009) |
|