# Switching pure states of the dissipative Heisenberg XXZ chain by local magnetic fields

## TL;DR

This paper demonstrates how local magnetic fields can switch the pure nonequilibrium stationary states of an open quantum Heisenberg XXZ spin chain, enabling control over spin current direction without losing state purity.

## Contribution

It introduces a method to invert spin current in an open quantum XXZ chain by tuning local magnetic fields, maintaining state purity and optimizing transport.

## Key findings

- Switching pure NESS by local magnetic fields is possible.
- Spin current can be inverted while preserving state purity.
- Optimal transport conditions are achieved through magnetic field adjustments.

## Abstract

The effects of a local magnetic field on nonequilibrium stationary states (NESS) of the open quantum $XXZ$ spin chain are investigated with a Lindblad master equation approach in the limit of strong dissipation. The local magnetic field is applied to a single bulk spin of the chain while the ends are kept at fixed polarizations by dissipation. We show that suitable changes of the local magnetic field permit to invert the spin current by switching pure NESS with opposite chiralities, while preserving the state purity and achieving optimal transport.