Fig. 4.

Hamiltonian perturbations. Time-dependent diffusion constant D(t) with the couplings staggered by an amount δJ at large anisotropy $\mathrm{\Delta }\in \{8,12\}$ (Upper) and next nearest neighbor couplings $J\prime$ at Δ = 10 (Lower) obtained from MPO simulations. Consistent with the theoretical prediction, D(t) exhibits a subdiffusive regime consistent with $D(t)\sim t^{-1/2}$ (shown as the shaded regions).