Detection of long-range entanglement in gapped quantum spin liquids by local measurements

Abstract

Topological order, reflected in long range patterns of entanglement, is quantified by the topological entanglement entropy (TEE) ${\hat{I}}^3$. We show that for gapped quantum spin liquids (QSL) it is possible to extract ${\hat{I}}^3$ using two-spin local correlators. We demonstrate our method for the gapped ${\mathbb{Z}}_2$ Kitaev spin liquid on a honeycomb lattice with anisotropic interactions. We show that the ${\hat{I}}^3=\log 2$ for ${\mathbb{Z}}_2$ topological order can be simply extracted from local two-spin correlators across two different bonds, with an accuracy comparable or higher than the Kitaev-Preskill construction. This implies that the different superselection sectors of ${\mathbb{Z}}_2$ gauge theory determined by global Wilson loop operators can be fully reflected locally in the matter majorana sector.

10 pages, 5 figures