{
  "id": "quant-ph/9909073",
  "version": "v3",
  "published": "1999-09-23T13:57:31.000Z",
  "updated": "2003-05-28T20:09:22.000Z",
  "title": "Quantum states and generalized observables: a simple proof of Gleason's theorem",
  "authors": [
    "P. Busch"
  ],
  "comment": "3 pages, revtex. New title, and presentation substantially revised, focus now being on the characterization of probability measures on the set of effects rather than the question of hidden variables",
  "journal": "Phys. Rev. Lett. 91, 120403 (2003)",
  "doi": "10.1103/PhysRevLett.91.120403",
  "categories": [
    "quant-ph"
  ],
  "abstract": "A quantum state can be understood in a loose sense as a map that assigns a value to every observable. Formalizing this characterization of states in terms of generalized probability distributions on the set of effects, we obtain a simple proof of the result, analogous to Gleason's theorem, that any quantum state is given by a density operator. As a corollary we obtain a von Neumann-type argument against non-contextual hidden variables. It follows that on an individual interpretation of quantum mechanics, the values of effects are appropriately understood as propensities.",
  "revisions": [
    {
      "version": "v3",
      "updated": "2003-05-28T20:09:22.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "quantum state",
      "simple proof",
      "gleasons theorem",
      "generalized observables",
      "non-contextual hidden variables"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Phys. Rev. Lett."
    },
    "note": {
      "typesetting": "RevTeX",
      "pages": 3,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}