Hidden quantum correlations in the ground states of quasiclassical spin systems

TL;DR

This paper investigates quantum correlations in frustrated spin systems, revealing that pairwise entanglement is short-ranged and that multi-site entanglement peaks near phase transitions, bridging classical and quantum spin models.

Contribution

It introduces a detailed analysis of entanglement in quasiclassical spin systems using linear spin-wave theory, highlighting the behavior of quantum correlations near phase transitions.

Findings

Pairwise entanglement is short-ranged and sometimes absent.

Multi-site entanglement peaks near phase transitions.

Entanglement behavior is modulated by the magnetic structure period.

Abstract

Frustrated spin models may lead to the formation of both classical non-collinear spin structures and unique quantum phases including highly entangled quantum spin liquids. Here, we study the entanglement and spatial quantum correlations in linear spin-wave theory around a classical spin-spiral ground state. We find that the entanglement between pairs of sites is short-ranged, and is completely absent in certain cases. In contrast, the entanglement hidden in multi-site clusters is peaked close to phase transitions and shows an asymptotic behavior modulated by the period of the magnetic structure. These findings motivate further exploring the connection in the entanglement properties of fully quantum and of quasiclassical spin models.