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CsdLean4.Empirical.CSD.QuantumChaos.DerivedCoupling

Q1: the derived coupling — operator norm → flip measure #

Category: 3-Local (CSD-ontic record layer; specs/BACKLOG.md §Q Q1, the H7 residue).

Every record-coupling measure in the §H thread so far was posited (the fibreTrigger quarter-arc: exactly 1/2). This module derives one: the trigger is the region where a perturbation W actually moves the state — the overlap-deficit region — and its measure is bounded by the operator norm ‖W − 1‖ through Markov's inequality over the typicality measure. The same ‖W − 1‖ that prices the carrier at the operator level (CV/CarrierPersistence.lean, carrier_persistence_window) now prices the ontic flip probability: one knob, both levels.

Scope #

Stated on the corpus's Fin-indexed projective sector (CPN M, fubiniStudyMeasure), where the typicality measure lives; the CV chain's FieldConfig-indexed drives connect by re-indexing (bookkeeping, not mathematics — recorded, not done here). The trigger thresholds at a free δ; the threshold-free sharp version (flip measure = the deficit distribution itself) would need the distribution's law, not just its Markov bound — a recorded refinement, not claimed.

The overlap deficit #

noncomputable def CSD.Empirical.QuantumChaos.overlapDeficit {M : } (W : (Matrix.unitaryGroup (Fin M) )) (p : LF4.CPN M) :

The overlap deficit: how far the unitary W moves the ray p, measured by the normalised expectation gap 1 − Re⟨u, Wu⟩/‖u‖². Zero iff W fixes the state's expectation; ray-well-defined (overlapDeficit_mk); at most ‖W − 1‖ (overlapDeficit_le).

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    The deficit computed on any representative.

    The deficit descends continuously (the continuous_momentMap route).

    The deficit is nonnegative: a unitary cannot raise the normalised expectation above one (Cauchy–Schwarz + norm preservation).

    The pointwise operator-norm bound: the deficit never exceeds ‖W − 1‖.

    The Markov bridge #

    noncomputable def CSD.Empirical.QuantumChaos.deficitTrigger {M : } (W : (Matrix.unitaryGroup (Fin M) )) (δ : ) :

    The trigger: the region the perturbation genuinely moves.

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      The Markov bridge: the trigger's typicality measure is bounded by the operator norm — δ · μ_FS(trigger) ≤ ‖W − 1‖. An operator quantity has become a measure bound.

      The record-coupled ontic step, and the derived half-life #

      The deficit-triggered kick: the perturbed drive's projective flow on the sector, with the record kicked exactly where the perturbation genuinely moves the state.

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        ★★ The derived half-life bound — the H7 residue, discharged. A formed record survives n periods of the deficit-triggered dynamics except on a set whose measure is priced by the operator norm of the perturbation: δ · μ((intact n)ᶜ) ≤ n · ‖W − 1‖. The same ‖W − 1‖ that bounds the carrier's operator-level deviation (carrier_persistence_window) now bounds the ontic flip probability — ε derived, not posited.

        The sanity anchor: no perturbation, no erosion #

        The identity perturbation has zero deficit everywhere.

        No perturbation, no erosion — derived: at W = 1 the trigger is empty, the coupling is null, and a formed record persists almost surely at every period count.

        The derived coupling bites: the qubit phase flip, exactly #

        Generic attainment of the half-life bound is already settled (HalfLifeAttainment.lean: cyclicKick_halfLife_attained, equality on the cyclic kick). What remained for the derived coupling was the bite: is the deficit trigger ever more than null? Here it is computed exactly. For the qubit phase flip W = diag(−1, 1) the deficit is twice the moment coordinate (overlapDeficit_phaseFlipW), so the trigger is a moment super-level set — and the Duistermaat–Heckman law (fs_moment_pushforward_uniform) evaluates its typicality measure exactly: 1 − δ/2, strictly between 0 and 1 on δ ∈ (0, 2). The exact value also shows where Markov is loose: ‖W − 1‖ = 2, so the generic Q1 bound δ·μ ≤ 2 is trivial on this window, while the DH law pins the coupling — the generic bridge is for drives whose deficit law is unknown; when the law is available it should be used instead.

        The qubit phase flip diag(−1, 1): the observable unitary exp(iπ·diag(1, 0)).

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          The deficit of the phase flip is twice the moment coordinate: overlapDeficit (diag(−1,1)) p = 2·m₀(p). The perturbation's disturbance is read off the Kähler moment map.

          The derived coupling, exactly (qubit, phase flip): the trigger's typicality measure is 1 − δ/2 — the Duistermaat–Heckman law evaluates what Markov could only bound.

          The derived kick's coupling strength, exactly.

          ★★ The derived coupling bites: for δ ∈ (0, 2) the flip probability is strictly between 0 and 1 — the deficit-triggered kick genuinely couples, and the derived half-life bound below is about a real erosion channel, not a vacuous one.

          The half-life at the exact rate (qubit, phase flip): a formed record survives n periods except on measure at most n·(1 − δ/2) — the generic bound instantiated with the coupling the DH law computed, rather than the Markov estimate.