{
  "annotation_id": "91420e99-7011-45c6-814d-a5263a9b6ce2",
  "date_created": "2026-03-02T18:02:41.055000Z",
  "date_modified": "2026-03-02T18:02:41.055000Z",
  "file_hash": "a8b779035411e82d2992800068bbe2f5bbf11e40da2ada611ef8be4e42ee45d5",
  "private": false,
  "record": {
    "abstract": "We analyze and compare the characterization of a quantum device in terms of\nnoise, transmitted bit-error-rate (BER) and mutual information, showing how the\nnoise description is meaningful only for Gaussian channels. After reviewing the\ndescription of a quantum communication channel, we study the insertion of an\namplifier. We focus attention on the case of direct detection, where the linear\namplifier has a 3 decibels noise figure, which is usually considered an\nunsurpassable limit, referred to as the standard quantum limit (SQL). Both\nnoise and BER could be reduced using an ideal amplifier, which is feasible in\nprinciple. However, just a reduction of noise beyond the SQL does not generally\ncorrespond to an improvement of the BER or of the mutual information. This is\nthe case of a laser amplifier, where saturation can greatly reduce the noise\nfigure, although there is no corresponding improvement of the BER. Such\nmechanism is illustrated on the basis of Monte Carlo simulations.",
    "arxiv_id": "quant-ph/9801065",
    "authors": [
      "G. M. D\u0027Ariano",
      "C. Macchiavello",
      "L. Maccone"
    ],
    "categories": [
      "quant-ph"
    ],
    "doi": "10.1142/S0217979297001660",
    "journal_ref": "Int.J.Mod.Phys. B11 (1997) 3385",
    "title": "Noise, errors and information in quantum amplification",
    "url": "https://arxiv.org/abs/quant-ph/9801065"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "0b36c126-aa2c-4590-943f-b0def3e464b1",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}