{
  "id": "quant-ph/0609076",
  "version": "v1",
  "published": "2006-09-11T09:30:54.000Z",
  "updated": "2006-09-11T09:30:54.000Z",
  "title": "Maximum observable correlation for a bipartite quantum system",
  "authors": [
    "Michael J. W. Hall",
    "Erika Andersson",
    "Thomas Brougham"
  ],
  "comment": "Revtex, no figures",
  "journal": "Phys. Rev. A 74 (2006) 062308",
  "doi": "10.1103/PhysRevA.74.062308",
  "categories": [
    "quant-ph"
  ],
  "abstract": "The maximum observable correlation between the two components of a bipartite quantum system is a property of the joint density operator, and is achieved by making particular measurements on the respective components. For pure states it corresponds to making measurements diagonal in a corresponding Schmidt basis. More generally, it is shown that the maximum correlation may be characterised in terms of a `correlation basis' for the joint density operator, which defines the corresponding (nondegenerate) optimal measurements. The maximum coincidence rate for spin measurements on two-qubit systems is determined to be (1+s)/2, where s is the spectral norm of the spin correlation matrix, and upper bounds are obtained for n-valued measurements on general bipartite systems. It is shown that the maximum coincidence rate is never greater than the computable cross norm measure of entanglement, and a much tighter upper bound is conjectured. Connections with optimal state discrimination and entanglement bounds are briefly discussed.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2006-09-11T09:30:54.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "bipartite quantum system",
      "maximum observable correlation",
      "maximum coincidence rate",
      "joint density operator",
      "measurements"
    ],
    "tags": [
      "journal article"
    ],
    "publication": {
      "publisher": "APS",
      "journal": "Phys. Rev. A"
    },
    "note": {
      "typesetting": "RevTeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}