Multipartite entanglement hidden in vector-chiral correlations of spin-1/2 chains

@misc{shimokawa2026multipartite,
  title = {{Multipartite entanglement hidden in vector-chiral correlations of spin-1/2 chains}},
  author = {Tokuro Shimokawa},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2609.39258},
  eprint = {2609.39258},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.39258},
}

TY  - UNPB
TI  - Multipartite entanglement hidden in vector-chiral correlations of spin-1/2 chains
AU  - Tokuro Shimokawa
PY  - 2026
DA  - 2026/10/07
PB  - arXiv
DO  - 10.48550/arxiv.2609.39258
UR  - https://arxiv.org/abs/2609.39258
AB  - Characterizing entanglement in quantum materials through experimentally accessible observables remains a central challenge. Quantum Fisher information associated with sums of one-site spin operators provides one route by linking entanglement to measurable magnetic response functions. Extending this approach to local composite observables requires new entanglement bounds. Here we establish a rigorous bound for the total nearest-neighbour vector chirality of periodic spin-1/2 chains with an even number of sites. The quantum Fisher information per spin cannot exceed k+1 for any k-producible state, so exceeding this bound certifies entanglement depth of at least k+1. Combining infinite density-matrix renormalization group and thermal pure quantum-state calculations, we demonstrate multipartite entanglement encoded in vector-chiral correlations at zero and finite temperatures in an extended J_1-J_2 XXZ chain. The spin-current coupling between vector chirality and electric polarization offers, in principle, access to this witness through dielectric loss spectroscopy in multiferroic magnets, extending entanglement diagnostics beyond dipolar spin correlations.
ER  -