Equivalences between spin models induced by defects

TL;DR

This paper demonstrates that the spectrum of integrable spin chains remains unchanged under spin reordering and introduces defects to establish spectral equivalences between different boundary conditions, including diagonal and nondiagonal types.

Contribution

It shows spectral invariance under spin ordering and introduces defects to relate various boundary conditions in integrable spin chains.

Findings

Spectral invariance under spin reordering.

Defects induce equivalences between boundary conditions.

Relation between diagonal and nondiagonal boundary conditions.

Abstract

The spectrum of integrable spin chains are shown to be independent of the ordering of their spins. As an application we introduce defects (local spin inhomogeneities in homogenous chains) in two-boundary spin systems and, by changing their locations, we show the spectral equivalence of different boundary conditions. In particular we relate certain nondiagonal boundary conditions to diagonal ones.