Sector-Dependent CHSH Violation in Fibonacci Anyons, and Finite-Size Topological–CHSH Mutual Information in 2D Lattice Models

We quantify the mutual information I(T;S) between topological sector labels T and CHSH values S in two-dimensional lattice models. In the Z_2 lattice gauge theory on a 16×16 torus at inverse temperature β = 2.0, we measure I = 0.015 ± 0.011 bits, significant at >2σ in 9 out of 10 independent Monte Carlo runs (corroborated by gauge-invariant plaquette-strip observables, I = 0.018 ± 0.011 bits, >3σ in 21/21 runs); the crossover decomposition attributes this β = 2.0 signal to the anyonic (local-defect) component of the sector label rather than to the Wilson-loop component. A finite-size scaling analysis indicates that this sector–CHSH mutual information decays toward zero with system size. A crossover near β ~ 2.0 shifts the dominant information source from local defect structure to global Wilson-loop sectors. In the quantum toric code via exact diagonalization, abelian Z_2 anyons produce no local CHSH correlations at system sizes L ≥ 3, consistent with the inaccessibility of abelian topological entanglement to local Pauli operators. We systematically test and rule out three classical mechanisms for Bell violation, consistent with Fine's theorem. Most significantly, within an idealized TQFT model we find that braiding of Fibonacci anyons in the fusion space produces CHSH-form violation with |S| = 2.811 (99.4% of the Tsirelson bound), and that this violation is strongly sector-dependent: with fixed measurement settings (optimized at the winner sector), |S| ranges from near zero to 2.72 (CHSH violation in only 14% of sectors), while sector-adapted settings achieve CHSH violation in 99.5% of sectors. This is consistent with topology neither creating nor destroying entanglement, but determining the measurement basis required to observe it. Keywords: CHSH inequality, topological order, mutual information, lattice gauge theory, toric code, Fibonacci anyons, Ising anyons, Bell correlations, non-Abelian braiding Version notes (v2.3, following a comprehensive internal review of the full series): • The gauge-invariant plaquette-strip confirmation is re-anchored: the previously documented preliminary value I = 0.035 ± 0.016 bits (5 seeds) is replaced by I = 0.018 ± 0.011 bits with σ = 14.2 ± 11.4 and 21/21 seeds > 3σ, obtained from the expanded 21-seed recompute and confirmed by a second, independently written route (both scripts and result JSONs deposited). • The information decomposition of Table II is completely recomputed: every entry now comes from a deposited validation script (crossover_decomposition_validator.py) as a seed-set mean over five seeds with per-run optimized CHSH settings, replacing values that were previously hard-coded in the figure script from an analysis that was not part of the record; the significance column now reports how many of the five seeds exceed 2σ instead of a single-run σ, and the table gains a β = 1.5 row. Comparing every entry against the previous version: the mean-anyon column moves at β = 1.0 (17.8 → 17.9), β = 2.0 (2.5 → 2.7) and β = 2.5 (0.0 → 0.3); I_full moves at β = 1.0 (0.001 → 0.006), β = 2.5 (0.057 → 0.017), and β = 3.0 (0.320 → 0.000); I_Wilson moves at β = 1.0 (0.000 → 0.001), β = 2.5 (0.055 → 0.011), and β = 3.0 (0.316 → 0.000); I_anyons moves at β = 1.0 (0.001 → 0.002) and β = 2.0 (0.004 → 0.003). The β = 2.0 value of I_full (0.011) and of I_Wilson (0.001) are unchanged in the third decimal. The most consequential changes are at β = 2.5 and β = 3.0, where the earlier single-run values are replaced by seed-set values. The β = 3.0 row is zero because at that run length the sampled CHSH value is exactly constant in all five seeds (a single distinct value with zero variance in the deposited characterization), so any mutual information with it vanishes identically; sector transitions are not absent there (see the frozen-regime entry below). A second, independently implemented Monte Carlo engine confirms the β = 2.0 structure of the decomposition. • A characterization of the frozen regime is deposited (frozen_regime_characterization.py), covering both deposited engines at β = 2.5 and β = 3.0 on 40,000-measurement runs and, for the anchor engine at β = 3.0, additionally the 4000-measurement scale of Table II. Sector transitions occur on both of these scales at β = 3.0 (5–19 per 4000-measurement run in the anchor engine, 124–133 per 40,000 in the same engine, and 214–237 per 40,000 in the second engine), and in the anchor engine they are frequent at β = 2.5 on the long runs; the conditional variance of the CHSH value given the sector label remains close to its unconditional value wherever that value is nonzero. At the 4000-measurement scale the β = 3.0 decomposition row vanishes because the sampled CHSH value is exactly constant there, not because the sector label freezes. The earlier statements that the CHSH value becomes a near-deterministic function of the frozen sector label, and that sector transitions are rare throughout β ≥ 2.5, are corrected accordingly. Two undocumented transition counts are removed from the β ≥ 2.5 caveat: the β = 3.0 count is replaced by the measured rates (the earlier figure of about 7 per run lies inside the measured 5–19 range — it was undocumented, not wrong), and the β = 2.0 comparison count is removed without replacement, as no corresponding measurement is deposited. • The β = 3.0 row of the simulation-history table is marked as a single early frozen-regime run that is not reproduced by the deposited systematic seed set, and the corresponding bar in the overview figure carries the same annotation. • New content since v2.2: a finite-size scaling section (I(L) at β = 2.0 for L = 8–64, two independent Monte Carlo engines, BIC model comparison — the Z_2 mutual-information signal decays toward zero with system size and is reported as a finite-size effect), and a Related Work and Prior Art section. • Wording and framing corrections from the review pass: the Fine-bound passage is corrected (Fine's theorem requires a setting-independent hidden-variable weighting; the tested ρ(n|a,b) family is setting-dependent, so the empirical S = 2.000 cap is reported as a property of this particular family, not a general re-derivation of the Fine bound), and the abstract claim is aligned with the body ("confirming Fine's theorem empirically" → "consistent with Fine's theorem"). The uncertainty of the exponential-fit asymptote is corrected by a factor of ten (SEM reporting). Numerical values that changed in this release are listed explicitly in the entries above. • Companion-work title updated to match Paper 2's ratified retitling. Non-Abelian capitalization corrected to the series-wide form throughout. A hardcoded table reference is corrected to the actual table carrying the cited value. • Self-cite hardening: the three load-bearing companion citations point to the frozen Version-DOI of the exact cited version (10.5281/zenodo.21282566, 10.5281/zenodo.21327673, 10.5281/zenodo.21327799), and the companion Bell-algebra paper is now cited with its final title and Concept-DOI (10.5281/zenodo.21134322). • Deposit hardening from the series review: a deposited second-route script is repaired (one-line indentation error) and its comparison target updated to the v2.3 values; auxiliary script documentation is standardized to English; one deposited script and its result file are renamed, so their file names differ from v2.2. All headline values re-verified by rerunning the deposited reproduction scripts (bit-identical / statistically identical); the frozen-regime characterization script was extended in this release and is covered by its own entry above. In a final usability pass the deposit was exercised as a reader would: one script's output path is now anchored on its own location instead of the working directory, outdated header comments in two scripts are corrected (an obsolete paper title and version, a reference to a file that is not part of the record, a stale table number, and a byte-identity claim about a file outside the record), and the README now lists the third-party packages and the interpreter versions the release was checked with. No computed value is affected. • Clarifications added in this release: the detector reference angles θ_A, θ_B of the classical measurement model are now defined in the text; the sector-shuffle-corrected I(T;S) is defined explicitly (permutation-null-subtracted signal); and a caveat marks the Fibonacci sweep parameter δ as a representation-deformation parameter rather than a physical anyon parameter (verified in the companion landscape analysis, Appendix C). The simulation-parameter appendix now states the thermalization and measurement counts per deposited code path, replacing a single figure that combined two of them. • Three rows of the Fibonacci table (L = 4, 6, 7) are aligned with the cited companion version: the companion re-anchored its sector-phase optimisation from a 25-point to a 50-point δ grid, which raises those optima in the third decimal (|S| 2.224 → 2.225, 2.394 → 2.398, 2.535 → 2.536, with the corresponding concurrence and %-of-Tsirelson entries). The headline value at L = 12 (|S| = 2.811) is unchanged. • The data-and-code statement is corrected and made specific: it now names which tables and figures the deposited scripts regenerate, marks the per-seed table and the historical model rows as not script-backed, points the Fibonacci values at the companion record, and states the dual licence correctly (CC BY 4.0 for paper, figures and data; MIT for the deposited code) — the previous wording claimed CC BY for the code as well and claimed reproduction of every value in the paper. The second engine's file header is corrected accordingly, including a stale cross-reference number that did not match any version of Table II. • The XY-model annotation on the simulation-overview figure is corrected to match the value printed in Table VII (I = 0.001); the other four annotated bars already matched and are unchanged. •