{
  "annotation_id": "265b7fb6-7538-466a-9ee6-ed74e562af9a",
  "date_created": "2026-03-02T18:01:42.377000Z",
  "date_modified": "2026-03-02T18:01:42.377000Z",
  "file_hash": "6dcbc978558356cd47d657dc681cbfd247e56c5e49a1b73547d7730be42f3bc9",
  "private": false,
  "record": {
    "abstract": "We consider the Scharnhorst effect (anomalous photon propagation in the\nCasimir vacuum) at oblique incidence, calculating both photon speed and\npolarization states as functions of angle. The analysis is performed in the\nframework of nonlinear electrodynamics and we show that many features of the\nsituation can be extracted solely on the basis of symmetry considerations.\nAlthough birefringence is common in nonlinear electrodynamics it is not\nuniversal; in particular we verify that the Casimir vacuum is not birefringent\nat any incidence angle. On the other hand, group velocity is typically not\nequal to phase velocity, though the distinction vanishes for special directions\nor if one is only working to second order in the fine structure constant. We\nobtain an ``effective metric\u0027\u0027 that is subtly different from previous results.\nThe disagreement is due to the way that ``polarization sums\u0027\u0027 are implemented\nin the extant literature, and we demonstrate that a fully consistent\npolarization sum must be implemented via a bootstrap procedure using the\neffective metric one is attempting to define. Furthermore, in the case of\nbirefringence, we show that the polarization sum technique is intrinsically an\napproximation.",
    "arxiv_id": "quant-ph/0010055",
    "authors": [
      "Stefano Liberati",
      "Sebastiano Sonego",
      "Matt Visser"
    ],
    "categories": [
      "quant-ph",
      "gr-qc",
      "hep-th"
    ],
    "doi": "10.1103/PhysRevD.63.085003",
    "journal_ref": "Phys.Rev. D63 (2001) 085003",
    "title": "Scharnhorst effect at oblique incidence",
    "url": "https://arxiv.org/abs/quant-ph/0010055"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "20794d44-64a1-40e1-acee-4c9d271eea05",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}