{
  "abstract": "Exchange-based semiconductor qubits encompass a broad family of encodings constructed from singlet- and triplet-like spin states, several of which are compatible with operation at zero applied magnetic field. Their reliable operation requires characterization of environmental noise, residual idle interactions, and exchange-dependent decay, but this characterization often relies on multi-axis control calibration or deliberately engineered magnetic-field gradients. A simpler zero-applied-field diagnostic is particularly valuable for hybrid semiconductor-superconductor systems, in which magnetic fields can degrade superconducting components. Here, we use the intrinsic magnetic-field gradient produced by residual nuclear spins in isotopically enriched Si/SiGe to implement exchange oscillations between two quantum dots as a characterization tool without a micromagnet, dynamic nuclear polarization, or prior multi-axis calibration. Using Carr-Purcell-Meiboom-Gill exchange sequences, we extend the singlet coherence from $T_2^*=1.17\\pm0.02~μ$s to $T_2^{\\mathrm{CPMG}}=74.8\\pm1.8~μ$s with $N=70$ refocusing pulses. The oscillation phase resolves residual exchange in the tens-of-kilohertz regime and enables it to be mapped across the $(1,1)$ charge cell. These results establish intrinsic-gradient exchange oscillations as a simple, more relevant zero-field diagnostic for exchange-only and related semiconductor qubit encodings that is amenable to rapid, high-throughput device characterization.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.31093",
  "author_total": 9,
  "authors": [
    {
      "name": "Holly G. Stemp"
    },
    {
      "name": "Harry Hanlim Kang"
    },
    {
      "name": "Chih Hwan Yang"
    },
    {
      "name": "Gabriel D. Cutter"
    },
    {
      "name": "Frederike Brockmeyer"
    },
    {
      "name": "Patrick J. Strohbeen"
    },
    {
      "name": "Max Hays"
    },
    {
      "name": "Jeffrey A. Grover"
    },
    {
      "name": "William D. Oliver"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3wsbh0rd5s2jq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.31093",
  "fulltext_url": null,
  "id": "3wsbh0rd5s2jq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.31093",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mes-hall"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "3107|Quantum and electron transport phenomena"
    ]
  ],
  "openalex": "W7204943530",
  "pdf_url": "https://arxiv.org/pdf/2608.31093",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-31",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3wsbh0rd5s2jq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:41Z",
      "native_id": "2608.31093",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.31093"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mes-hall",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Device characterization of Si$/$SiGe double quantum dots using exchange oscillations in Earth's magnetic field",
  "title_text": "Device characterization of Si/SiGe double quantum dots using exchange oscillations in Earth's magnetic field",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:41Z",
  "url": "https://research.draconitic.com/paper/3wsbh0rd5s2jq",
  "venue": "arXiv",
  "versions": []
}