{
  "annotation_id": "bedcc787-a0bb-491b-ac27-73b9ec801d39",
  "date_created": "2026-03-02T18:02:27.456000Z",
  "date_modified": "2026-03-02T18:02:27.456000Z",
  "file_hash": "9340b9bd9e6d4273b0ab691209f609e21c7725c6482bab6764e4717fb567ba96",
  "private": false,
  "record": {
    "abstract": "We construct a single observable measurement of which mean value on four\ncopies of an {\\it unknown} two-qubit state is sufficient for unambiguous\ndecision whether the state is separable or entangled. In other words, there\nexists a universal collective entanglement witness detecting all two-qubit\nentanglement. The test is directly linked to a function which characterizes to\nsome extent the entanglement quantitatively. This function is an entanglement\nmonotone under so--called local pure operations and classical communication\n(pLOCC) which preserve local dimensions. Moreover it provides tight upper and\nlower bounds for negativity and concurrence. Elementary quantum computing\ndevice estimating unknown two-qubit entanglement is designed.",
    "arxiv_id": "quant-ph/0604109",
    "authors": [
      "Remigiusz Augusiak",
      "Maciej Demianowicz",
      "Pawel Horodecki"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.77.030301",
    "journal_ref": "Physical Review A 77, 030301(R) (2008)",
    "title": "Universal observable detecting all two-qubit entanglement and   determinant based separability tests",
    "url": "https://arxiv.org/abs/quant-ph/0604109"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "af8122e3-8b19-4edc-89c4-04500896efc0",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}