# Rectification and One-Way Street for the Energy Current in Boundary-Driven Asymmetric Quantum Spin Chains

## TL;DR

This paper investigates energy transport in boundary-driven asymmetric quantum spin chains, revealing phenomena like energy rectification and a one-way energy current unaffected by boundary conditions, with implications for quantum device engineering.

## Contribution

It demonstrates the occurrence of energy rectification and a one-way street for energy current in asymmetric quantum spin chains, extending the understanding of boundary-driven quantum transport.

## Key findings

- Energy rectification is a universal feature in studied models.
- A one-way energy current persists without external magnetic field.
- Results apply broadly to other interactions and boundary conditions.

## Abstract

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