{
  "abstract": "Fast entangling gates and low-interaction idling require distinct operating conditions in superconducting quantum processors. We experimentally realize a transmon-C-shunt-transmon (TCT) device in which a flux-tunable, three-junction capacitively shunted flux-qubit coupler connects two transmon data qubits. The C-shunt coupler provides a flux-tunable, positively anharmonic spectrum for tailoring the interactions between the data qubits. Conditional Ramsey and swap measurements identify an idle region with near-zero residual ZZ interaction strength and suppressed transverse exchange. At this bias, simultaneous single-qubit interleaved randomized benchmarking yields X-gate fldelities above 99.7%, consistent with individual operation. A 45 ns nonadiabatic controlled-Z (CZ) gate achieves an interleaved randomized benchmarking fldelity estimate of 99.23(15)%. Numerical simulations identify coupler energy relaxation as an important limitation on CZ-gate fldelity and indicate that extending the coupler lifetime can improve gate performance. These results demonstrate the experimental feasibility of C-shunt flux-qubit couplers for combining low-interaction idling with fast entangling operations between transmon qubits.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18477",
  "author_total": 19,
  "authors": [
    {
      "name": "Weiping Yuan"
    },
    {
      "name": "Silu Zhao"
    },
    {
      "name": "Li Li"
    },
    {
      "name": "Chenglin Deng"
    },
    {
      "name": "Zhenghe Liu"
    },
    {
      "name": "Yu Liu"
    },
    {
      "name": "Tianming Li"
    },
    {
      "name": "Mingchuan Wang"
    },
    {
      "name": "Bingjie Chen"
    },
    {
      "name": "Guihan Liang"
    },
    {
      "name": "Jiacheng Song"
    },
    {
      "name": "Jinming Guo"
    },
    {
      "name": "Shuaili Wang"
    },
    {
      "name": "Mingxuan Zhou"
    },
    {
      "name": "Xiaohui Song"
    },
    {
      "name": "Kai Xu"
    },
    {
      "name": "Heng Fan"
    },
    {
      "name": "Zhongcheng Xiang"
    },
    {
      "name": "Dongning Zheng"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7bm86r9g2z18d.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18477",
  "fulltext_url": null,
  "id": "7bm86r9g2z18d",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.18477",
  "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 Information and Cryptography"
    ]
  ],
  "openalex": "W7221811995",
  "pdf_url": "https://arxiv.org/pdf/2610.18477",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7bm86r9g2z18d.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:11Z",
      "native_id": "2610.18477",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18477"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Experimental Realization of a C-Shunt Flux-Qubit Coupler for Controlled-Z Gates between Transmons",
  "title_text": "Experimental Realization of a C-Shunt Flux-Qubit Coupler for Controlled-Z Gates between Transmons",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:11Z",
  "url": "https://research.draconitic.com/paper/7bm86r9g2z18d",
  "venue": "arXiv",
  "versions": []
}