{
  "id": "quant-ph/0011072",
  "version": "v2",
  "published": "2000-11-16T09:10:37.000Z",
  "updated": "2003-07-29T10:04:28.000Z",
  "title": "On the reversible extraction of classical information from a quantum source",
  "authors": [
    "Howard Barnum",
    "Patrick Hayden",
    "Richard Jozsa",
    "Andreas Winter"
  ],
  "comment": "22 pages, Latex2e, journal version",
  "journal": "Proc. Roy. Soc. (Lond.) A (2001), vol 457, p2019-2039",
  "doi": "10.1098/rspa.2001.0816",
  "categories": [
    "quant-ph"
  ],
  "abstract": "Consider a source E of pure quantum states with von Neumann entropy S. By the quantum source coding theorem, arbitrarily long strings of signals may be encoded asymptotically into S qubits/signal (the Schumacher limit) in such a way that entire strings may be recovered with arbitrarily high fidelity. Suppose that classical storage is free while quantum storage is expensive and suppose that the states of E do not fall into two or more orthogonal subspaces. We show that if E can be compressed with arbitrarily high fidelity into A qubits/signal plus any amount of auxiliary classical storage then A must still be at least as large as the Schumacher limit S of E. Thus no part of the quantum information content of E can be faithfully replaced by classical information. If the states do fall into orthogonal subspaces then A may be less than S, but only by an amount not exceeding the amount of classical information specifying the subspace for a signal from the source.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2003-07-29T10:04:28.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "classical information",
      "reversible extraction",
      "arbitrarily high fidelity",
      "orthogonal subspaces",
      "schumacher limit"
    ],
    "tags": [
      "journal article"
    ],
    "note": {
      "typesetting": "LaTeX",
      "pages": 22,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}