Rectification and one-way street for the energy current in boundary-driven asymmetric quantum spin chains

摘要

Motivated by the demand for efficient quantum devices to engineer energy transport, we analyze someinhomogeneous quantum spin systems, including XXZ chains, with magnetization baths at the ends.With a goalof finding general properties, we study the effects of suitable transformations on the boundary-driven Lindbladmaster equation associated with the dynamics of the systems. For asymmetric models with target polarizationat the edges or twisted XY boundary gradients, we show the properties of the steady state, which establishthe features of the energy current irrespective of the system size and the regime of transport. We show theubiquitous occurrence of energy rectification and, more interestingly, of an unusual phenomenon: in the absenceof an external magnetic field, there is a one-way street for the energy current, i.e., the direction of the energycurrent does not change as we invert the magnetization baths at the boundaries. Given the extensiveness of theprocedures, which essentially involve the properties of the Lindblad master equation, our results certainly followfor other interactions and other boundary conditions.Moreover, our results indicate graded spin chains as genuinequantum rectifiers.