{
  "abstract": "Variational preparation of thermofield double (TFD) states can require deep quantum circuits, particularly for interacting many-body systems. Reducing these circuits while retaining high fidelity is therefore crucial for TFD-state preparation on noisy quantum processors. We study this problem by applying the multi-angle quantum approximate optimization algorithm (ma-QAOA) to TFD-state preparation and introducing two top-down sequential angle-pruning algorithms. Starting from the optimized initial ma-QAOA circuit, both algorithms sequentially remove Pauli-string evolutions with small optimized angles and reoptimize the remaining parameters after each removal. We apply these algorithms to Gaussian and binary Sachdev--Ye--Kitaev (SYK) models in both dense and sparse cases. We find that ma-QAOA prepares the target TFD states with high fidelity and that sequential small-angle pruning retains high fidelity while reducing the circuit depth, particularly at low temperature. Moreover, using the post-reoptimization cost in sequential small-angle pruning further improves the fidelity. For the binary sparse $N=10$ SYK model at $β=10$, $88.8\\%$--$92.1\\%$ of the nonlocal Pauli-string evolutions are removed while retaining an average fidelity of approximately $95\\%$. Finally, we propose extensions of the sequential pruning algorithms toward quantum--classical hybrid implementation.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.02793",
  "author_total": 3,
  "authors": [
    {
      "name": "Haji Muhammad Husnain Ashfaq"
    },
    {
      "name": "Moongul Byun"
    },
    {
      "name": "Keun-Young Kim"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f1kvr6ay2y2cb.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.02793",
  "fulltext_url": null,
  "id": "f1kvr6ay2y2cb",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.02793",
  "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": "W7207615834",
  "pdf_url": "https://arxiv.org/pdf/2609.02793",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-02",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/f1kvr6ay2y2cb.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:16Z",
      "native_id": "2609.02793",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.02793"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Variational preparation of thermofield double states for SYK models via multi-angle QAOA: sequential angle pruning for circuit reduction",
  "title_text": "Variational preparation of thermofield double states for SYK models via multi-angle QAOA: sequential angle pruning for circuit reduction",
  "type": "preprint",
  "updated_at": "2026-10-30T12:18:16Z",
  "url": "https://research.draconitic.com/paper/f1kvr6ay2y2cb",
  "venue": "arXiv",
  "versions": []
}