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Nonequilibrium quantum dynamics of a charge carrier doped into a Mott insulator

We study real-time dynamics of a charge carrier introduced into undoped Mott insulator propagating under a constant electric field F on the t-J ladder and square lattice. We calculate quasistationary current. In both systems adiabatic regime is observed followed by the positive differential resistivity (PDR) at moderate fields where carrier mobility is determined. Quantitative differences between ladder and 2-dimensional (2D) system emerge when at large fields both systems enter negative differential resistivity (NDR) regime. In the ladder system Bloch-like oscillations prevail, while in 2D the current remains finite, proportional to 1/F. The crossover between PDR and NDR regime in 2D is accompanied by a change of the spatial structure of the propagating spin polaron.