{
  "annotation_id": "642b0ab3-88ce-489f-bebd-0fa959305e43",
  "date_created": "2026-03-02T18:02:16.973000Z",
  "date_modified": "2026-03-02T18:02:16.973000Z",
  "file_hash": "8ceb354df6ae43109efe619228f6054c26cdcc8b953856e757a299a25db95e6c",
  "private": false,
  "record": {
    "abstract": "We studied the entangled state for a one-dimensional $S=1/2$\nantiferromagnetic quantum spin chain in a transverse field. We calculate the\nground state using the density matrix renormalization group and discuss how the\nentangled state changes around a quantum phase transition (QPT) point. By\nanalyzing concurrence $C(\\rho)$ for two-qubit density matrix $\\rho$ after the\nLewenstein-Sanpera decomposition, $\\rho=\\Lambda \\rho_s + (1-\\Lambda) \\rho_e $,\nwhere $\\rho_s$ is a separable density matrix and $\\rho_e$ is a pure entangled\nstate obtained by a linear combination of Bell states, we find singular\nbehaviors both in $C(\\rho_e)$ and $1-\\Lambda$ at the QPT point.\u0026#12288;\n$C(\\rho_e)$ includes the effects of quantum fluctuations, which manifest the\ncompetition between the antiferromagnetic spin fluctuation and the effect of\ntransverse field in the transverse Ising model. The quantum fluctuation shows\nthe singular maximum at the QPT point as expected from the general picture of\nphase transition. In contrast, $1-\\Lambda$ reveals the singular minimum at QPT\npoint.",
    "arxiv_id": "quant-ph/0505168",
    "authors": [
      "Akira Kawaguchi",
      "Kaoru Shimizu"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "Singular behavior of an entangled state for a one-dimensional quantum   spin system",
    "url": "https://arxiv.org/abs/quant-ph/0505168"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "1ad0bd35-1b59-40f2-9fea-15068a3ed5da",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}