{
  "annotation_id": "883ff8fb-524c-4ade-a971-b21eb8409b7f",
  "date_created": "2026-03-02T18:01:59.916000Z",
  "date_modified": "2026-03-02T18:01:59.916000Z",
  "file_hash": "574ed66ef55a2abc85302e3ea8c5064c5a6998e853d90da3820ad4bca34a22f6",
  "private": false,
  "record": {
    "abstract": "We address the problem of finding optimal CPTP (completely positive, trace\npreserving) maps between a set of binary pure states and another set of binary\ngeneric mixed state in a two dimensional space. The necessary and sufficient\nconditions for the existence of such CPTP maps can be discussed within a simple\ngeometrical picture. We exploit this analysis to show the existence of an\noptimal quantum repeater which is superior to the known repeating strategies\nfor a set of coherent states sent through a lossy quantum channel. We also show\nthat the geometrical formulation of the CPTP mapping conditions can be a\nsimpler method to derive a state-dependent quantum (anti) cloning machine than\nthe study so far based on the explicit solution of several constraints imposed\nby unitarity in an extended Hilbert space.",
    "arxiv_id": "quant-ph/0304011",
    "authors": [
      "A. Carlini",
      "M. Sasaki"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.68.042327",
    "journal_ref": "Phys. Rev. A 68 (2003), 042327",
    "title": "Geometrical Conditions for CPTP Maps and their Application to a Quantum   Repeater and a State-dependent Quantum Cloning Machine",
    "url": "https://arxiv.org/abs/quant-ph/0304011"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "1009059f-d725-4c9f-905f-b2096336a308",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}