  We consider charge and spin transport in the one-dimensional Hubbard model at
infinite temperature, half-filling and zero magnetization. Implementing
matrix-product-operator simulations of the non-equilibrium steady states of
boundary-driven open Hubbard chains for up to 100 sites we find clear evidence
of diffusive transport for any (non-zero and finite) value of the interaction
U.

Strongly Correlated Electrons;Quantum Physics