The open Heisenberg chain under boundary fields: a magnonic logic gate

TL;DR

This paper presents an exact analysis of spin transport in a quantum Heisenberg chain with boundary fields, revealing a phase transition that enables the chain to function as a highly sensitive magnonic logic gate.

Contribution

It provides an exact matrix product state solution for spin current in the Heisenberg chain under boundary fields, demonstrating a quantum phase transition relevant for magnonic logic devices.

Findings

Discontinuous spin-valve-like quantum phase transition observed

Exact calculation of spin current for any chain size

Chain acts as a sensitive magnonic logic gate

Abstract

We study the spin transport in the quantum Heisenberg spin chain subject to boundary magnetic fields and driven out of equilibrium by Lindblad dissipators. An exact solution is given in terms of matrix product states, which allows us to calculate exactly the spin current for any chain size. It is found that the system undergoes a discontinuous spin-valve-like quantum phase transition from ballistic to sub-diffusive spin current, depending on the value of the boundary fields. Thus, the chain behaves as an extremely sensitive magnonic logic gate operating with the boundary fields as the base element.