{
  "id": "quant-ph/0506047",
  "version": "v2",
  "published": "2005-06-06T13:16:18.000Z",
  "updated": "2006-04-20T22:44:13.000Z",
  "title": "No-relationship between impossibility of faster-than-light quantum communication and distinction of ensembles with the same density matrix",
  "authors": [
    "Chuan Wang",
    "Gui Lu Long",
    "Yang Sun"
  ],
  "comment": "4 pages and 3 figures",
  "journal": "Commun. Theor. Phys. (Beijing, China) 44 (2005) pp. 622-624",
  "categories": [
    "quant-ph"
  ],
  "abstract": "It has been claimed in the literature that impossibility of faster-than-light quantum communication has an origin of indistinguishability of ensembles with the same density matrix. We show that the two concepts are not related. We argue that: 1) even with an ideal single-atom-precision measurement, it is generally impossible to produce two ensembles with exactly the same density matrix; or 2) to produce ensembles with the same density matrix, classical communication is necessary. Hence the impossibility of faster-than-light communication does not imply the indistinguishability of ensembles with the same density matrix.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2006-04-20T22:44:13.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "density matrix",
      "faster-than-light quantum communication",
      "impossibility",
      "distinction",
      "no-relationship"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 4,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}