Status: Phase 0 — Project Initialization (2026-07-21)
Series: Phase V of The Qubit Delusion (following Phase I: The Qubit Delusion, Phase II: Beyond the Qubit, Phase III: The Physics of Computation, Phase IV: The Problem-Substrate Mapping)
Quick start: See PROJECT-PLAN.md for charter, WBS, and core claim lock.
The transmon qubit — the dominant superconducting qubit architecture — is described as a "two-level quantum system." It is not. It is a bosonic mode with an infinite ladder: a harmonic oscillator made anharmonic by the Josephson potential. The Josephson junction's anharmonicity is doing the work that Pauli exclusion would do for free in a fermionic system. But it is not free. The energy gap is finite, the isolation is imperfect, and the leakage is measurable.
This paper uses the transmon as THE case study in a physics-deep analysis of the two-level approximation's failure. It bridges QNFO's ontological critique with quantitative experimental evidence: EJ/EC trade-off curves, leakage measurements from published experiments, and the DRAG pulse as an explicit admission that the two-level model must be actively enforced against the bosonic reality.
PROJECT-PLAN.md— Charter, WBS, milestones, core claim lock, risk registerdocs/— Prior work, references, research papersartifacts/— Literature reviews, gate memos, test resultsnotebooks/— Working notes, calculation notebooksreleases/— Versioned Zenodo-ready bundles