{
  "annotation_id": "0472dacb-5a17-4e74-a390-21e7d7bc8852",
  "date_created": "2026-03-02T18:01:38.675000Z",
  "date_modified": "2026-03-02T18:01:38.675000Z",
  "file_hash": "9b40266cac01a72436aab1456f895ec55d33b5fde6dd41a65e0c8a592bb217cd",
  "private": false,
  "record": {
    "abstract": "We investigate coherence in one- and two-photon optical systems, both\ntheoretically and experimentally. In the first case, we develop the density\noperator representing a single photon state subjected to a non-dissipative\ncoupling between observed (polarization) and unobserved (frequency) degrees of\nfreedom. We show that an implementation of ``bang-bang\u0027\u0027 quantum control\nprotects photon polarization information from certain types of decoherence. In\nthe second case, we investigate the existence of a \"decoherence-free\" subspace\nof the Hilbert space of two-photon polarization states under the action of a\nsimilar coupling. The density operator representation is developed analytically\nand solutions are obtained numerically.\n  NOTE: This manuscript is taken from the author\u0027s undergraduate thesis (A.B.\nDartmouth College, June 2000, advised by Dr. Walter E. Lawrence), under the\nsupervision of Dr. Paul G. Kwiat.",
    "arxiv_id": "quant-ph/0010001",
    "authors": [
      "Andrew J. Berglund"
    ],
    "categories": [
      "quant-ph"
    ],
    "title": "Quantum coherence and control in one- and two-photon optical systems",
    "url": "https://arxiv.org/abs/quant-ph/0010001"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "311f9c25-f78f-4ffc-adbb-c3782e865cae",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}