{
  "abstract": "Sample-based quantum subspace methods construct a small subspace from measured basis states and solve the target problem classically within it. We study these methods for heat conduction in magnetized plasmas, where the anisotropy $χ_\\parallel/χ_\\perp$ reaches $10^8$ to $10^{10}$. We prove two results for the energy-norm Galerkin solution. First, if the measurement basis is aligned with the flux surfaces and the subspace contains the poloidal-mode-zero block, the error is bounded by $\\|r_0\\|_{L^+}(χ_\\parallel-χ_\\perp)^{-1/2}$, where the numerator does not depend on $χ_\\parallel$. The bound is sharp, so the accuracy improves as the anisotropy grows. Second, in the computational basis, a subspace that misses a single node of a flux surface suppresses the flux-function component there as $χ_\\parallel^{-1/2}$, which gives an error floor when the limiting solution is nonzero on that surface. We verify both results on a shaped cross-section and on a KSTAR-like Miller equilibrium with ten qubits. At $χ_\\parallel/χ_\\perp=10^9$, the computational basis gives an error of order unity for every shot budget, whereas a quantum Fourier transform on the poloidal register gives $1.3\\times10^{-5}$. The same barrier limits sample-based quantum diagonalization. The aligned measurement needs no time evolution, so the circuit is only state preparation and a five-qubit quantum Fourier transform. On a ten-qubit superconducting processor, the aligned basis gives a median error of $7.0\\times10^{-6}$ with 768 shots, whereas the computational basis gives errors above 0.94 up to $1.2\\times10^4$ shots. A trapped-ion processor shows the same behavior.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2611.07102",
  "author_total": 2,
  "authors": [
    {
      "name": "Doyeol"
    },
    {
      "name": "Ahn"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fv8f5yfesp3xz.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2611.07102",
  "fulltext_url": null,
  "id": "fv8f5yfesp3xz",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2611.07102",
  "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",
      "physics.comp-ph"
    ],
    [
      "arxiv",
      "physics.plasm-ph"
    ],
    [
      "arxiv",
      "quant-ph"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2611.07102",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-04",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fv8f5yfesp3xz.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T18:21:30Z",
      "native_id": "2611.07102",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2611.07102"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.comp-ph",
      "subfield": "computational"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.plasm-ph",
      "subfield": "plasma"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Field-aligned measurement removes the anisotropy barrier of sample-based quantum subspace solvers for magnetized-plasma heat conduction",
  "title_text": "Field-aligned measurement removes the anisotropy barrier of sample-based quantum subspace solvers for magnetized-plasma heat conduction",
  "type": "preprint",
  "updated_at": "2026-11-08T21:20:39Z",
  "url": "https://research.draconitic.com/paper/fv8f5yfesp3xz",
  "venue": "arXiv",
  "versions": []
}