{
  "abstract": "High-fidelity entangling gates are essential for quantum information processing. In transmon circuits, higher excited states provide additional pathways for engineering interactions within the computational subspace. Here we demonstrate controlled-Z (CZ) gates that exploit two noncomputational states, $\\ket{02}$ and $\\ket{20}$, through selective Floquet coupling. The nontrivial parametric modulation can activate both auxiliary transitions from $\\ket{11}$ while suppressing the leading exchange between $\\ket{01}$ and $\\ket{10}$. Based on this approach, we develop two gate protocols: a nonadiabatic round trip through a bright auxiliary superposition and adiabatic evolution along a zero-energy dark state, both achieving average gate fidelities above $99.99\\%$ in numerical simulations. Control of the modulation phase further extends the bright-state protocol to conventional and unconventional geometric CZ gates. Effective-model simulations show that unconventional control improves tolerance to residual $ZZ$ coupling and static qubit-frequency offsets relative to conventional control over the parameter ranges examined. Simulations including neighboring spectator qubits show that the original nonadiabatic bright-state and adiabatic dark-state CZ protocols retain high gate fidelities. This framework offers new routes toward the experimental realization of CZ gates and their geometric implementations.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.27834",
  "author_total": 6,
  "authors": [
    {
      "name": "Yutao Chen"
    },
    {
      "name": "Jia-Chi Zhang"
    },
    {
      "name": "Tian-Ming Li"
    },
    {
      "name": "Yu Liu"
    },
    {
      "name": "Kai Xu"
    },
    {
      "name": "Heng Fan"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c7vkpqsc7s5d8.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.27834",
  "fulltext_url": null,
  "id": "c7vkpqsc7s5d8",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.27834",
  "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",
      "quant-ph"
    ],
    [
      "openalex",
      "1702|Quantum Information and Cryptography"
    ]
  ],
  "openalex": "W7223139278",
  "pdf_url": "https://arxiv.org/pdf/2610.27834",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/c7vkpqsc7s5d8.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2610.27834",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.27834"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Controlled-Z Gates via Floquet Coupling to Two Auxiliary States in Transmon Circuits",
  "title_text": "Controlled-Z Gates via Floquet Coupling to Two Auxiliary States in Transmon Circuits",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/c7vkpqsc7s5d8",
  "venue": "arXiv",
  "versions": []
}