A model of dephasing in shift current processes

The shift current is a second order nonlinear effect in the optical field thought to be the dominant transport mechanism in many ferroelectric materials and to carry information about the topology of the Bloch wave functions. The shift current requires quantum coherence in the solid. We construct a simple model of electrons coupled to a chain of one-dimensional ions lacking inversion symmetry. We analyze the thermalization of electrons within the model at high and low excitations frequencies (close to the band edge). The model allows the study of decoherence in shift current process beyond the classical transport regime.