{
  "id": "oai:papers.qnfo.org:planar-bosonic-error-correction-with-heavy-fluxonium-a-quantitative-reassessment",
  "slug": "planar-bosonic-error-correction-with-heavy-fluxonium-a-quantitative-reassessment",
  "title": "Planar Fluxonium‑Controlled Bosonic Error Correction: A Quantitative Error‑Budget Reassessment (Corrected Version)",
  "authors": [
    "Rowan Brad Quni-Gudzinas"
  ],
  "abstract": "Bosonic quantum error correction (QEC) encodes a logical qubit in a single harmonic oscillator, promising fault tolerance with far fewer physical components than qubit‑based surface codes. Recent planar demonstrations using a heavy fluxonium ancilla report a bit‑flip lifetime of T₁^bf = 451 ± 70~mus and a logical‑lifetime extension factor of F = 1.59 ± 0.05. The gap addressed here is the absence of a transparent, arithmetic‑level analysis that connects these reported numbers to the underlying error budget and per‑cycle ancilla error probability. This corrected version also repairs two defects of the earlier release: a citation that had been misdescribed as an analysis of two‑level error correction for multi‑spin molecular qubits, and a photon‑budget figure obtained by multiplying a cited resource ratio by the lifetime extension factor under an unjustified linearity assumption. We propagate the reported lifetimes through standard QEC error‑budget relations and derive: (i) an ancilla bit‑flip rate Γ_bf = (2.22 ± 0.34)×10³~s^-1, (ii) a 37.1\\%±2.0\\% removal of the logical decay rate, and (iii) a per‑cycle ancilla error of 2.19\\%±0.34\\% for an assumed 10~mus correction cycle. The photon‑budget advantage remains the cited $5$–40× fewer photons per logical qubit at p_L = 10^-6; the previously claimed $8.0$–64× figure is withdrawn. The corrected chain gives hardware designers a concrete error‑budget target and a falsifiable prediction for future fluxonium‑GKP experiments.",
  "abstract_markdown": "Bosonic quantum error correction (QEC) encodes a logical qubit in a single harmonic oscillator, promising fault tolerance with far fewer physical components than qubit‑based surface codes. Recent planar demonstrations using a heavy fluxonium ancilla report a bit‑flip lifetime of $T_1^{\\mathrm{bf}} = 451 \\pm 70~\\mu\\mathrm{s}$ and a logical‑lifetime extension factor of $F = 1.59 \\pm 0.05$. The gap addressed here is the absence of a transparent, arithmetic‑level analysis that connects these reported numbers to the underlying error budget and per‑cycle ancilla error probability. This corrected version also repairs two defects of the earlier release: a citation that had been misdescribed as an analysis of two‑level error correction for multi‑spin molecular qubits, and a photon‑budget figure obtained by multiplying a cited resource ratio by the lifetime extension factor under an unjustified linearity assumption. We propagate the reported lifetimes through standard QEC error‑budget relations and derive: (i) an ancilla bit‑flip rate $\\Gamma_{\\mathrm{bf}} = (2.22 \\pm 0.34)\\times10^{3}~\\mathrm{s}^{-1}$, (ii) a $37.1\\%\\pm2.0\\%$ removal of the logical decay rate, and (iii) a per‑cycle ancilla error of $2.19\\%\\pm0.34\\%$ for an assumed $10~\\mu\\mathrm{s}$ correction cycle. The photon‑budget advantage remains the cited $5$–$40\\times$ fewer photons per logical qubit at $p_L = 10^{-6}$; the previously claimed $8.0$–$64\\times$ figure is withdrawn. The corrected chain gives hardware designers a concrete error‑budget target and a falsifiable prediction for future fluxonium‑GKP experiments.",
  "date": "2026-10-09",
  "first_published": "2026-10-09",
  "last_revised": "2026-11-01T05:21:29Z",
  "modified": "2026-11-01T05:21:29Z",
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  "url": "https://papers.qnfo.org/papers/planar-bosonic-error-correction-with-heavy-fluxonium-a-quantitative-reassessment",
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  "version_url": "https://papers.qnfo.org/papers/planar-bosonic-error-correction-with-heavy-fluxonium-a-quantitative-reassessment/v/3.0.0",
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    "creators": [
      {
        "name": "Rowan Brad Quni-Gudzinas",
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    "titles": [
      {
        "title": "Planar Fluxonium‑Controlled Bosonic Error Correction: A Quantitative Error‑Budget Reassessment (Corrected Version)"
      }
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    "publicationYear": "2026",
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        "date": "2026-10-09",
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        "description": "Bosonic quantum error correction (QEC) encodes a logical qubit in a single harmonic oscillator, promising fault tolerance with far fewer physical components than qubit‑based surface codes. Recent planar demonstrations using a heavy fluxonium ancilla report a bit‑flip lifetime of T₁^bf = 451 ± 70~mus and a logical‑lifetime extension factor of F = 1.59 ± 0.05. The gap addressed here is the absence of a transparent, arithmetic‑level analysis that connects these reported numbers to the underlying error budget and per‑cycle ancilla error probability. This corrected version also repairs two defects of the earlier release: a citation that had been misdescribed as an analysis of two‑level error correction for multi‑spin molecular qubits, and a photon‑budget figure obtained by multiplying a cited resource ratio by the lifetime extension factor under an unjustified linearity assumption. We propagate the reported lifetimes through standard QEC error‑budget relations and derive: (i) an ancilla bit‑flip rate Γ_bf = (2.22 ± 0.34)×10³~s^-1, (ii) a 37.1\\%±2.0\\% removal of the logical decay rate, and (iii) a per‑cycle ancilla error of 2.19\\%±0.34\\% for an assumed 10~mus correction cycle. The photon‑budget advantage remains the cited $5$–40× fewer photons per logical qubit at p_L = 10^-6; the previously claimed $8.0$–64× figure is withdrawn. The corrected chain gives hardware designers a concrete error‑budget target and a falsifiable prediction for future fluxonium‑GKP experiments.",
        "descriptionType": "Abstract"
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