title: Diffusion and ballistic transport in one-dimensional quantum systems.
abstract: It has been conjectured that transport in integrable one-dimensional systems is necessarily ballistic. The large diffusive response seen experimentally in nearly ideal realizations of the S=1/2 1D Heisenberg model is therefore puzzling and has not been explained so far. Here, we show that, contrary to common belief, diffusion is universally present in interacting 1D systems subject to a periodic lattice potential. We present a parameter-free formula for the spin-lattice relaxation rate which is in excellent agreement with experiment. Furthermore, we calculate the current decay directly in the thermodynamic limit using a time-dependent density matrix renormalization group algorithm and show that an anomalously large time scale exists even at high temperatures.
authors.affiliation: Department of Physics and Research Center OPTIMAS, TU Kaiserslautern, D-67663 Kaiserslautern, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Sirker
authors.forename: R G
authors.initials: RG
authors.lastname: Pereira
authors.forename: I
authors.initials: I
authors.lastname: Affleck