{
  "annotation_id": "88a7d621-4503-422d-8a92-38177199c25c",
  "date_created": "2026-03-02T18:01:39.313000Z",
  "date_modified": "2026-03-02T18:01:39.313000Z",
  "file_hash": "d9d6976ac4f5692e4a170b76c013b3a1f44ff313e840141bb33c4a7c1d3670d3",
  "private": false,
  "record": {
    "abstract": "We derive the optimal N-photon two-mode input state for obtaining an estimate\n\\phi of the phase difference between two arms of an interferometer. For an\noptimal measurement [B. C. Sanders and G. J. Milburn, Phys. Rev. Lett. 75, 2944\n(1995)], it yields a variance (\\Delta \\phi)^2 \\simeq \\pi^2/N^2, compared to\nO(N^{-1}) or O(N^{-1/2}) for states considered by previous authors. Such a\nmeasurement cannot be realized by counting photons in the interferometer\noutputs. However, we introduce an adaptive measurement scheme that can be thus\nrealized, and show that it yields a variance in \\phi very close to that from an\noptimal measurement.",
    "arxiv_id": "quant-ph/0009117",
    "authors": [
      "D. W. Berry",
      "H. M. Wiseman"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1103/PhysRevLett.85.5098",
    "journal_ref": "Phys. Rev. Lett. 85, 5098 (2000)",
    "title": "Optimal states and almost optimal adaptive measurements for quantum   interferometry",
    "url": "https://arxiv.org/abs/quant-ph/0009117"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "a052cb81-462d-47d9-a957-e6c028325352",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}