Quantum transport of strongly interacting fermions in one dimension at far-out-of-equilibrium

In the study of quantum transport, much has been known for dynamics near thermal equilibrium. However, quantum transport far away from equilibrium is much less well understood–the linear response approximation does not hold for physics far-out-of-equilibrium in general. In this work, motivated by recent cold atom experiments on probing quantum many-body dynamics of a one-dimensional XXZ spin chain, we study the strong interaction limit of the one-dimensional spinless fermion model, which is dual to the XXZ spin chain. We develop a highly efficient computation algorithm for simulating the non-equilibrium dynamics of this system exactly, and examine the non-equilibrium dynamics starting from a density modulation quantum state. We find ballistic transport in this strongly correlated setting, and show a plane-wave description emerges at long-time evolution. We also observe sharp distinction between transport velocities in short and long times as induced by interaction effects, and provide a quantitative interpretation for the long-time transport velocity.