{
  "abstract": "Optically addressable, biocompatible spin qubits represent promising platforms for quantum sensing. However, current efforts have focused on genetic encodability and microwave-based approaches thus far limited to organic radicals. Utilizing time-resolved Faraday rotation, we measured electron spin coherence in plastocyanin, a protein in the photosynthetic electron transport chain. Persisting hundreds of picoseconds, this is the first measurement of spin coherence in a metalloprotein under ambient conditions. We show how the protein’s active-site geometric and electronic structure responsible for biological function also enabled a spin–photon interface. A related blue copper protein—azurin—also demonstrated all-optical spin coherence. The ability to measure bioinorganic spin coherence under functional conditions foreshadows metalloproteins as native quantum sensors and opens questions about the potential role of spin coherences in electron transfer.",
  "abstract_shown": true,
  "affiliations": [
    "Arthur Amos Noyes Laboratory of Chemical Physics",
    "California Institute of Technology"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Christian A. Totoiu"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Erica Sutcliffe"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Demetrios A. Dresios"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Ryan G. Hadt",
      "orcid": "0000-0001-6026-1358"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1zt871v42j0n2.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15009712/v1",
  "fulltext_url": null,
  "id": "1zt871v42j0n2",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009712/v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1304|Electron Spin Resonance Studies"
    ]
  ],
  "openalex": "W7215106561",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15009712/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-01",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/1zt871v42j0n2.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:21Z",
      "native_id": "10.26434/chemrxiv.15009712",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009712/v1"
    }
  ],
  "subjects": [
    {
      "field": "biochemistry",
      "origin": "openalex:1304|Electron Spin Resonance Studies",
      "subfield": "biophysics"
    }
  ],
  "title": "All-Optical Spin Coherence in a Photosynthetic Electron-Transfer Metalloprotein",
  "title_text": "All-Optical Spin Coherence in a Photosynthetic Electron-Transfer Metalloprotein",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:21Z",
  "url": "https://research.draconitic.com/paper/1zt871v42j0n2",
  "venue": "ChemRxiv",
  "versions": []
}