{
  "annotation_id": "5f2c046e-0027-4dad-b627-8377e721a83a",
  "date_created": "2026-03-02T18:02:31.147000Z",
  "date_modified": "2026-03-02T18:02:31.147000Z",
  "file_hash": "bab840469324c20d47071c84f64f252f4d3116a40a5e990cd9c388d26244404f",
  "private": false,
  "record": {
    "abstract": "We investigate two-way and one-way single-photon quantum key distribution\n(QKD) protocols in the presence of loss introduced by the quantum channel. Our\nanalysis is based on a simple precondition for secure QKD in each case. In\nparticular, the legitimate users need to prove that there exists no separable\nstate (in the case of two-way QKD), or that there exists no quantum state\nhaving a symmetric extension (one-way QKD), that is compatible with the\navailable measurements results. We show that both criteria can be formulated as\na convex optimisation problem known as a semidefinite program, which can be\nefficiently solved. Moreover, we prove that the solution to the dual\noptimisation corresponds to the evaluation of an optimal witness operator that\nbelongs to the minimal verification set of them for the given two-way (or\none-way) QKD protocol. A positive expectation value of this optimal witness\noperator states that no secret key can be distilled from the available\nmeasurements results. We apply such analysis to several well-known\nsingle-photon QKD protocols under losses.",
    "arxiv_id": "quant-ph/0611151",
    "authors": [
      "Marcos Curty",
      "Tobias Moroder"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevA.75.052336",
    "journal_ref": "Phys. Rev. A 75, 052336 (2007)",
    "title": "On single-photon quantum key distribution in the presence of loss",
    "url": "https://arxiv.org/abs/quant-ph/0611151"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "d7e8a08d-2d74-454a-8c11-7336b890543d",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}