{
  "abstract": "Absorption spectroscopy identifies molecules by detecting frequency-dependent optical loss, and its fundamental limit is a quantum channel-discrimination problem. In this work, we develop a general framework for characterizing the ultimate quantum limit of molecular absorption spectroscopy without collective measurements: we formulate it as an asymmetric quantum hypothesis testing task between different absorption channels. Using a semidefinite-programming formulation, we construct optimal probe states and compare them with coherent-state photon counting, Fock states, and two-mode squeezed vacuum probes. We introduce a random-loss channel model for imperfectly known background transmission, reflecting the fact that a blank experiment need not return all incident photons due to scattering, solvent absorption, or collection losses. Our results show that optimized non-classical probes can substantially outperform conventional laser spectroscopy, and that the advantage is robust to realistic baseline random loss. % In multi-frequency spectroscopy, the optimization also determines how photons should be allocated across absorption lines, revealing an additional resource-allocation advantage beyond single-mode state engineering. We illustrate our framework using infrared detection of 4-nitrophenol against chemically relevant comparison molecules, showing how quantum channel-discrimination methods provide constructive performance limits for molecular spectroscopy under realistic photon constraints.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.27344",
  "author_total": 5,
  "authors": [
    {
      "name": "Anirban Dey"
    },
    {
      "name": "Akib Karim"
    },
    {
      "name": "Pieter Kok"
    },
    {
      "name": "Mark M. Wilde"
    },
    {
      "name": "Zixin Huang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c7vhmtyksqh2x.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.27344",
  "fulltext_url": null,
  "id": "c7vhmtyksqh2x",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.27344",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "1702|Quantum Information and Cryptography"
    ]
  ],
  "openalex": "W7214200036",
  "pdf_url": "https://arxiv.org/pdf/2609.27344",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-23",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/c7vhmtyksqh2x.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:56Z",
      "native_id": "2609.27344",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.27344"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Limits for molecular spectroscopy from quantum channel discrimination",
  "title_text": "Limits for molecular spectroscopy from quantum channel discrimination",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:56Z",
  "url": "https://research.draconitic.com/paper/c7vhmtyksqh2x",
  "venue": "arXiv",
  "versions": []
}