Intersublattice entanglement entropy as an extensive property in antiferromagnets

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. Furthermore, 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.

Automated summary

Recent advancements in understanding ordered magnets have led to quantification of entanglement content as an intensive property, with entanglement entropy scaling with volume in bipartite ordered antiferromagnets. Analytic results show dimensionality-dependent constant, validated against numerical analysis of a 1D system. This evaluation provides useful shortcuts for obtaining central-cut entanglement entropy in 1D systems and area law in higher-dimensional magnets.