{
  "annotation_id": "619e00f0-c578-4e52-8a09-3bae64b521a5",
  "date_created": "2026-03-02T18:01:38.496000Z",
  "date_modified": "2026-03-02T18:01:38.496000Z",
  "file_hash": "3b5ff4f425a6260474c206e51e71482c22b03c18b28931233b42dc6096693953",
  "private": false,
  "record": {
    "abstract": "Twin observables, i.e. opposite subsystem observables A+ and A- that are\nindistinguishable in measurement in a given mixed or pure state W, are\ninvestigated in detail algebraicly and geometrically. It is shown that there is\na far-reaching correspondence between the detectable (in W) spectral entities\nof the two operators. Twin observables are state-dependently quantum-logically\nequivalent, and direct subsystem measurement of one of them ipso facto gives\nrise to the indirect (i.e. distant) measurement of the other. Existence of\nnontrivial twins requires singularity of W. Systems in thermodynamic\nequilibrium do not admit subsystem twins. These observables may enable one to\nsimplify the matrix representing W.",
    "arxiv_id": "quant-ph/0004085",
    "authors": [
      "F. Herbut",
      "M. Damnjanovic"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1088/0305-4470/33/34/308",
    "journal_ref": "Journal of Physics A 33 (2000) 6023",
    "title": "Mixed-state twin observables",
    "url": "https://arxiv.org/abs/quant-ph/0004085"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "b4ec4ebc-a794-4f5f-a377-9d89a1524fc9",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}