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Exact Analysis of Entanglement in Gapped Quantum Spin Chains

Hosho Katsura·Takaaki Hirano·Yasuhiro Hatsugai
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Abstract

We investigate the entanglement properties of the valence-bond-solid states with generic integer-spin $S$. Using the Schwinger boson representation of the valence-bond-solid states, the entanglement entropy, the von Neumann entropy of a subsystem, is obtained exactly and its relationship with the usual correlation function is clarified. The saturation value of the entanglement entropy, $2 \log_2 (S+1)$, is derived explicitly and is interpreted in terms of the edge-state picture. The validity of our analytical results and the edge-state picture is numerically confirmed. We also propose a novel application of the edge state as a qubit for quantum computation.

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Hosho Katsura, Takaaki Hirano, Yasuhiro Hatsugai. 2007-02-08. Exact Analysis of Entanglement in Gapped Quantum Spin Chains. https://doi.org/10.1103/physrevb.76.012401

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