{
  "annotation_id": "89353915-083e-499d-a81f-3aac1c3fb788",
  "date_created": "2026-03-02T18:02:20.411000Z",
  "date_modified": "2026-03-02T18:02:20.411000Z",
  "file_hash": "72b0cea8863800d5b082afa6e36c94882148b7bad06753e79ab9b68eac2f354e",
  "private": false,
  "record": {
    "abstract": "It is common belief among physicists that entangled states of quantum systems\nloose their coherence rather quickly. The reason is that any interaction with\nthe environment which distinguishes between the entangled sub-systems collapses\nthe quantum state. Here we investigate entangled states of two trapped Ca$^+$\nions and observe robust entanglement lasting for more than 20 seconds.",
    "arxiv_id": "quant-ph/0508021",
    "authors": [
      "H. Haeffner",
      "F. Schmidt-Kaler",
      "W. Haensel",
      "C. F. Roos",
      "T. Koerber",
      "M. Chwalla",
      "M. Riebe",
      "J. Benhelm",
      "U. D. Rapol",
      "C. Becher",
      "R. Blatt"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1007/s00340-005-1917-z",
    "journal_ref": "Appl. Phys. B 81, 151 (2005)",
    "title": "Robust entanglement",
    "url": "https://arxiv.org/abs/quant-ph/0508021"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "d95c98b6-02a2-45f9-a20d-7efbe354e964",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}