{
  "abstract": "Reaching a degenerate ground-state manifold and sampling it uniformly are distinct properties of a quantum annealer. We quantify this distinction using an Ising ring with additional couplings between maximally separated sites. For antiferromagnetic benchmark couplings and $N \\geq 5$, we derive the exact ground-state energy, degeneracy, and defect structure for each congruence class of $N$ modulo four. This classification separates ground-state hit probability from conditional sampling bias. We embed instances with up to 162 logical spins on a D-Wave Advantage processor using length-two chains and compare its output with simulated annealing on the embedded and logical problems. For a frustrated $N=83$ instance, the processor visits 164 of the 166 exact ground states, yet the conditional distributions over states and defect sectors remain nonuniform. For $N=160$, the processor has a larger ground-state hit probability than logical simulated annealing (0.869 versus 0.519), but also a larger total-variation distance from uniformity (0.317 versus 0.136). A pause during the anneal raises the ground-state hit probability from 0.42 to 0.86 without restoring uniform sampling. These results identify a relaxation window and demonstrate that optimization success and sampling quality need not improve together, providing an exactly characterized benchmark for open-system quantum annealing.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.29035",
  "author_total": 2,
  "authors": [
    {
      "name": "Masaru Hitomi"
    },
    {
      "name": "Masayuki Ohzeki"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c8jm68k27hc8a.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.29035",
  "fulltext_url": null,
  "id": "c8jm68k27hc8a",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.29035",
  "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 Computing Algorithms and Architecture"
    ]
  ],
  "openalex": "W7223217655",
  "pdf_url": "https://arxiv.org/pdf/2610.29035",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/c8jm68k27hc8a.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:19Z",
      "native_id": "2610.29035",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.29035"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Optimization versus fair sampling in quantum annealing: An exactly characterized frustrated Ising benchmark",
  "title_text": "Optimization versus fair sampling in quantum annealing: An exactly characterized frustrated Ising benchmark",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:19Z",
  "url": "https://research.draconitic.com/paper/c8jm68k27hc8a",
  "venue": "arXiv",
  "versions": []
}