{
  "annotation_id": "fda219f9-f93c-4f8d-b305-29c3e7c596c5",
  "date_created": "2026-03-02T18:01:42.528000Z",
  "date_modified": "2026-03-02T18:01:42.528000Z",
  "file_hash": "e5a4f2f40280e43ee882860df79766121c08faedccc5b05ec2a02752f5cc9d28",
  "private": false,
  "record": {
    "abstract": "Consider a source E of pure quantum states with von Neumann entropy S. By the\nquantum source coding theorem, arbitrarily long strings of signals may be\nencoded asymptotically into S qubits/signal (the Schumacher limit) in such a\nway that entire strings may be recovered with arbitrarily high fidelity.\nSuppose that classical storage is free while quantum storage is expensive and\nsuppose that the states of E do not fall into two or more orthogonal subspaces.\nWe show that if E can be compressed with arbitrarily high fidelity into A\nqubits/signal plus any amount of auxiliary classical storage then A must still\nbe at least as large as the Schumacher limit S of E. Thus no part of the\nquantum information content of E can be faithfully replaced by classical\ninformation. If the states do fall into orthogonal subspaces then A may be less\nthan S, but only by an amount not exceeding the amount of classical information\nspecifying the subspace for a signal from the source.",
    "arxiv_id": "quant-ph/0011072",
    "authors": [
      "Howard Barnum",
      "Patrick Hayden",
      "Richard Jozsa",
      "Andreas Winter"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1098/rspa.2001.0816",
    "journal_ref": "Proc. Roy. Soc. (Lond.) A (2001), vol 457, p2019-2039",
    "title": "On the reversible extraction of classical information from a quantum   source",
    "url": "https://arxiv.org/abs/quant-ph/0011072"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "3eca8c38-ff16-4dfd-94f1-3299e4b98ec4",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}