[
  {
    "id": "ARR-2026-2WNM69XY548JHVMC-v2",
    "type": "article",
    "title": "Classical limits and robust Gaussian coding gaps for compound bosonic fading channels",
    "author": [
      {
        "literal": "Lluis Eriksson"
      }
    ],
    "issued": {
      "date-parts": [
        [
          2026,
          10,
          26
        ]
      ]
    },
    "publisher": "AIRR.SCIENCE",
    "archive": "AIRR.SCIENCE",
    "archive_location": "ARR-2026-2WNM69XY548JHVMC",
    "version": "v2",
    "genre": "Research preprint",
    "URL": "https://airr.science/papers/ARR-2026-2WNM69XY548JHVMC/versions/v2/",
    "note": "Research preprint; ARR-2026-2WNM69XY548JHVMC v2. Not peer reviewed by AIRR. Working paper; not admitted to the AIRR accepted collection.",
    "abstract": "We study unassisted classical communication through memoryless mixtures of noisy, phase-insensitive bosonic Gaussian channels. Both thermal noise and photon budget scale with an energy parameter. An explicit measure-prepare representation converts every quantum block code, including entangled codewords and collective receivers, into a classical code with identical error and an exactly quantified cost increment. The same simulation works for an unknown fixed mixing law. A Gaussian-smoothing estimate and a uniform finite-alphabet reduction give an explicit O(E^-1) comparison with a classical compound variational value, optimizing one input law before taking the worst mixing law. For a matched-reset example we prove a strict separation from the time-sharing hull of Gaussian coherent modulations. Matching bounds determine the high-energy limit of a regularized Holevo functional with Gaussian average marginals. A block-uniform energy-controlled continuity modulus removes exact marginal Gaussianity and Gaussianity of the full average. Separate photon truncation and empirical moment concentration cover almost every product coherent Gaussian random codebook from a fixed finite deterministic schedule. Strict cost slack or an explicit common rescaling enforces physical feasibility. This yields an operational converse conditioned on reliability, below an unrestricted non-Gaussian common-code rate at sufficiently large energy. It neither constructs a good decoder for every random book nor covers every protocol described as Gaussian. The Gaussian, coding and continuity tools have established antecedents."
  }
]