Intersublattice entanglement entropy as an extensive property in antiferromagnets

TL;DR

This paper demonstrates that the entanglement entropy between sublattices in antiferromagnets scales extensively with volume, becoming a universal, dimension-dependent property, validated through analytical and DMRG methods.

Contribution

It introduces the concept of intersublattice entanglement entropy as an extensive, universal property in antiferromagnets, supported by analytical and numerical validation.

Findings

EE scales with volume in antiferromagnets

EE density is a universal constant depending on dimensionality

Analytical results agree with DMRG analysis in 1D

Abstract

Recent advancements in our understanding of ordered magnets call for a quantification of their entanglement content on an equal footing with classical thermodynamic quantities, such as the total magnetic moment. We evaluate the entanglement entropy (EE) between the two sublattices of a bipartite ordered antiferromagnet finding it to scale with volume. Thus, the EE density becomes an intensive property and is evaluated to be a universal dimensionality-dependent constant when exchange is the dominant interaction. Our analytic results are validated against the DMRG-based analysis of a one-dimensional (1D) system, finding good agreement. Further, our evaluated EE per bond provides a useful shortcut towards obtaining the central-cut EE in 1D, and the area law in higher-dimensional magnets.