{
  "abstract": "Hyperfine constant $A$ is a key parameter of the hyperfine structure and underpins precision spectroscopy and metrology. In this Letter, we develop a magnetic-field-calibration-free method for determining the ground-state hyperfine constant $A$ in an ultracold $^{40}$K Fermi gas by utilizing a pair of magnetically insensitive (\"clock\") transitions. This overcomes the stringent magnetic-field calibration requirements of conventional methods. We measure the transition frequency between these two magnetically insensitive transitions with Hz-level resolution over a range of magnetic fields, and obtain the ground-state hyperfine constant $A = -h\\times 285.730536(2)\\,\\mathrm{MHz}$, corresponding to an absolute uncertainty of about $2\\,\\mathrm{Hz}$. Our value reduces the uncertainty by nearly three orders of magnitude compared with previous determinations, providing a substantially improved reference for high-precision spectroscopy and metrology with $^{40}$K.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Phys. Rev. Lett. 137, 133401 (2026)",
  "arxiv": "2609.02572",
  "author_total": 11,
  "authors": [
    {
      "name": "Yajing Yang"
    },
    {
      "name": "Biao Shan"
    },
    {
      "name": "Yuhang Zhao"
    },
    {
      "name": "Jiahui Shen"
    },
    {
      "name": "Zhuxiong Ye"
    },
    {
      "name": "Liangchao Chen"
    },
    {
      "name": "Zengming Meng"
    },
    {
      "name": "Pengjun Wang"
    },
    {
      "name": "Wei Han"
    },
    {
      "name": "Jing Zhang"
    },
    {
      "name": "Lianghui Huang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1yx88dgvha8t4.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.02572",
  "fulltext_url": null,
  "id": "1yx88dgvha8t4",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.02572",
  "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",
      "cond-mat.quant-gas"
    ],
    [
      "arxiv",
      "physics.atom-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.02572",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/1yx88dgvha8t4.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:12Z",
      "native_id": "2609.02572",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.02572"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.quant-gas",
      "subfield": "amo"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.quant-gas",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Magnetic-Field-Calibration-Free Determination of the Hyperfine Constant $A$ in Ultracold Fermi gases of $^{40}$K",
  "title_text": "Magnetic-Field-Calibration-Free Determination of the Hyperfine Constant A in Ultracold Fermi gases of ^40K",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:12Z",
  "url": "https://research.draconitic.com/paper/1yx88dgvha8t4",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1103/7sjf-yj2z",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}