{
  "abstract": "High-fidelity single-shot readout of superconducting qubits is essential for fault-tolerant quantum computation. Without a quantum-limited amplifier such as a Josephson parametric amplifier, the cryogenic high-electron-mobility-transistor (HEMT) low-noise amplifier (LNA) at the 4 K stage is the dominant noise source in the readout chain. HEMT LNAs are conventionally characterized by Y-factor measurements of the noise temperature $T_N$, independently of the quantum measurement they ultimately serve. Here we present a qubit-in-the-loop benchmarking method. The method uses the two-dimensional IQ histogram of single-shot readout as a direct figure of merit. We apply it to three state-of-the-art cryogenic InP HEMT LNAs with 53\\%, 60\\%, and 70\\% channel indium content, together with a commercial reference amplifier. The 60\\% and 70\\% devices have similar $T_N$ in Y-factor measurements, both lower than the 53\\% device. The 70\\% device has the highest gain, but qubit readout SNR and assignment fidelity $\\mathcal{F}_a$ instead peak at 60\\%. Using this method, we map $\\mathcal{F}_a$ against HEMT LNA dc power consumption for each device. $\\mathcal{F}_a$ does not simply saturate with increasing power. For several devices it declines above a device-dependent power well below typical operating points. For the 60\\% device, which has the highest overall $\\mathcal{F}_a$, about 1~mW is needed to maintain $\\mathcal{F}_a > 85\\%$. Across all four devices, $\\mathcal{F}_a > 80\\%$ is reached with as little as about 0.3~mW, roughly an order of magnitude below typical operating points. These results establish a qubit-referenced benchmarking methodology and provide practical guidance for amplifier selection and bias in power-constrained multi-qubit readout systems.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.07250",
  "author_total": 1,
  "authors": [
    {
      "name": "Junjie Li"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/90je6r16zcrn0.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.07250",
  "fulltext_url": null,
  "id": "90je6r16zcrn0",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.07250",
  "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.app-ph"
    ],
    [
      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "1702|Quantum Information and Cryptography"
    ]
  ],
  "openalex": "W7211993695",
  "pdf_url": "https://arxiv.org/pdf/2609.07250",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-09",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/90je6r16zcrn0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:12Z",
      "native_id": "2609.07250",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.07250"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.app-ph",
      "subfield": "applied-instrumentation"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Qubit-Based Benchmarking of InP HEMT LNAs: Readout Fidelity Versus Power Consumption",
  "title_text": "Qubit-Based Benchmarking of InP HEMT LNAs: Readout Fidelity Versus Power Consumption",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:12Z",
  "url": "https://research.draconitic.com/paper/90je6r16zcrn0",
  "venue": "arXiv",
  "versions": []
}