{
  "annotation_id": "0c344554-8a15-4d1e-bc02-db66d890ea2c",
  "date_created": "2026-03-02T18:02:13.028000Z",
  "date_modified": "2026-03-02T18:02:13.028000Z",
  "file_hash": "e7daf7e391ee2992676649698cac98824f729c033267a3f04b884881d5378d6e",
  "private": false,
  "record": {
    "abstract": "We consider quantum channels with two senders and one receiver. For an\narbitrary such channel, we give multi-letter characterizations of two different\ntwo-dimensional capacity regions. The first region is comprised of the rates at\nwhich it is possible for one sender to send classical information, while the\nother sends quantum information. The second region consists of the rates at\nwhich each sender can send quantum information. For each region, we give an\nexample of a channel for which the corresponding region has a single-letter\ndescription. One of our examples relies on a new result proved here, perhaps of\nindependent interest, stating that the coherent information over any degradable\nchannel is concave in the input density operator. We conclude with connections\nto other work and a discussion on generalizations where each user\nsimultaneously sends classical and quantum information.",
    "arxiv_id": "quant-ph/0501045",
    "authors": [
      "Jon Yard",
      "Igor Devetak",
      "Patrick Hayden"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1109/TIT.2008.924665",
    "journal_ref": "IEEE Transactions on Information Theory 54:3091-3113, 2008",
    "title": "Capacity Theorems for Quantum Multiple Access Channels:   Classical-Quantum and Quantum-Quantum Capacity Regions",
    "url": "https://arxiv.org/abs/quant-ph/0501045"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "2fa245f0-2e01-49b4-93ab-93fce483552d",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}