This research establishes an exact, matrix-free framework for spectral analysis of Fibonacci-constrained quantum systems, demonstrating how exponentially expanding Hilbert spaces can admit computational descriptions whose complexity grows only linearly with chain length at any fixed spectral moment order. The investigation focuses on the open PXP quantum chain, whose admissible configurations obey a nearest-neighbor exclusion constraint and form a Hilbert space of dimension dim(Hₙ) = Fₙ₊₂. By combining Fibonacci combinatorics, Zeckendorf indexing, temporal-mask transfer operators, and exact integer arithmetic, the study develops a unified mathematical approach to spectral moments, constrained quantum dynamics, and gauge-sensitive observables without explicitly constructing the exponentially large Hamiltonian matrix. The central result is a universal rational hierarchy of even spectral moments, expressed through the generating function Σₙ₌₀∞ Tr(Aₙ²ᵐ) zⁿ = Pₘ(z) / (1 − z − z²)ᵐ⁺¹, with deg Pₘ ≤ 3m + 2. This theorem establishes that every fixed-order even spectral moment possesses a rational generating function governed by a power of the Fibonacci characteristic polynomial. Consequently, infinitely many spectral moments across increasing chain lengths can be reconstructed from a finite collection of exact initial values. Explicit rational expressions are derived for the fourth, sixth, and eighth spectral moments, accompanied by integer recurrence relations and independently reproducible computational certificates. The underlying temporal-mask transfer identity reduces fixed-order moment evaluation to O(n) arithmetic operations, even with spatially inhomogeneous hopping amplitudes and local diagonal fields. Its computational constants depend exponentially on moment order, but not on the exponentially growing Hilbert-space dimension. A complementary result introduces an exact gauge-sensitive fourth-moment certificate for quantum chains carrying occupation-dependent hopping phases. The spectral response obeys the identity Tr(Hₙ,φ⁴) − Tr(Hₙ,₀⁴) = 8(cos φ − 1) Sₙ, where Sₙ is obtained through a Fibonacci-based weighted recurrence requiring only O(n) arithmetic operations. Remarkably, this identity remains valid under arbitrary static real diagonal disorder, provided the diagonal energies and hopping magnitudes remain unchanged between phase settings. It therefore isolates a precisely defined gauge-dependent contribution to the fourth spectral moment without requiring diagonalization or knowledge of the complete spectrum. The certificate reconstructs a dimensionless flux response rather than an absolute quantum-action scale. The broader significance lies in demonstrating that exponential state-space growth does not necessarily imply exponential computational complexity for every exact spectral observable. The results connect constrained quantum many-body physics, Fibonacci graph theory, rational generating functions, and finite-state transfer methods within a common algebraic framework. All reported coefficients are supported by exact-integer verification rather than numerical fitting, and the established complexity bounds concern arithmetic operations rather than total bit complexity. The work provides a reproducible mathematical foundation for further investigations of spectral invariants, gauge responses, quantum constraints, and scalable symbolic computation, while restricting its formal claims to the specified finite-dimensional Hamiltonian models. Keywords: Fibonacci-constrained quantum chains · PXP Hamiltonian · Rational spectral hierarchy · Matrix-free computation · Temporal-mask transfer · Zeckendorf indexing · Gauge invariants · Exact spectral moments · Quantum many-body systems · Integer verification
This research establishes an exact, matrix-free framework for spectral analysis of Fibonacci-constrained quantum systems, demonstrating how exponentially expanding Hilbert spaces can admit computational descriptions whose complexity grows only linearly with chain length at any fixed spectral moment order. The investigation focuses on the open PXP quantum chain, whose admissible configurations obey a nearest-neighbor exclusion constraint and form a Hilbert space of dimension dim(Hₙ) = Fₙ₊₂. By combining Fibonacci combinatorics, Zeckendorf indexing, temporal-mask transfer operators, and exact integer arithmetic, the study develops a unified mathematical approach to spectral moments, constrained quantum dynamics, and gauge-sensitive observables without explicitly constructing the exponentially large Hamiltonian matrix. The central result is a universal rational hierarchy of even spectral moments, expressed through the generating function Σₙ₌₀∞ Tr(Aₙ²ᵐ) zⁿ = Pₘ(z) / (1 − z − z²)ᵐ⁺¹, with deg Pₘ ≤ 3m + 2. This theorem establishes that every fixed-order even spectral moment possesses a rational generating function governed by a power of the Fibonacci characteristic polynomial. Consequently, infinitely many spectral moments across increasing chain lengths can be reconstructed from a finite collection of exact initial values. Explicit rational expressions are derived for the fourth, sixth, and eighth spectral moments, accompanied by integer recurrence relations and independently reproducible computational certificates. The underlying temporal-mask transfer identity reduces fixed-order moment evaluation to O(n) arithmetic operations, even with spatially inhomogeneous hopping amplitudes and local diagonal fields. Its computational constants depend exponentially on moment order, but not on the exponentially growing Hilbert-space dimension. A complementary result introduces an exact gauge-sensitive fourth-moment certificate for quantum chains carrying occupation-dependent hopping phases. The spectral response obeys the identity Tr(Hₙ,φ⁴) − Tr(Hₙ,₀⁴) = 8(cos φ − 1) Sₙ, where Sₙ is obtained through a Fibonacci-based weighted recurrence requiring only O(n) arithmetic operations. Remarkably, this identity remains valid under arbitrary static real diagonal disorder, provided the diagonal energies and hopping magnitudes remain unchanged between phase settings. It therefore isolates a precisely defined gauge-dependent contribution to the fourth spectral moment without requiring diagonalization or knowledge of the complete spectrum. The certificate reconstructs a dimensionless flux response rather than an absolute quantum-action scale. The broader significance lies in demonstrating that exponential state-space growth does not necessarily imply exponential computational complexity for every exact spectral observable. The results connect constrained quantum many-body physics, Fibonacci graph theory, rational generating functions, and finite-state transfer methods within a common algebraic framework. All reported coefficients are supported by exact-integer verification rather than numerical fitting, and the established complexity bounds concern arithmetic operations rather than total bit complexity. The work provides a reproducible mathematical foundation for further investigations of spectral invariants, gauge responses, quantum constraints, and scalable symbolic computation, while restricting its formal claims to the specified finite-dimensional Hamiltonian models. Keywords: Fibonacci-constrained quantum chains · PXP Hamiltonian · Rational spectral hierarchy · Matrix-free computation · Temporal-mask transfer · Zeckendorf indexing · Gauge invariants · Exact spectral moments · Quantum many-body systems · Integer verification
Preprint of the article "A fixed-level certification dichotomy for an infinite family of frustration-free spin chains" (22 pages, no figures). To every finite loopless directed graph T the paper attaches a rational, range-three, frustration-free spin-chain interaction: arcs of T carry hopping bands for domain walls, missing arcs act as hard local penalties. The main theorem is the exact three-term equivalence: T is acyclic <=> liminf_m gap_m(T) > 0 <=> delta_LTI(5) > 0, where gap_m is the spectral gap of the periodic chain on m sites and delta_LTI(5) is the value of the local translation-invariant (LTI) semidefinite certification hierarchy at level 5, its first sound level. The certification level is fixed while the size of the graph and the local Hilbert-space dimension are unbounded across the family. To the author's knowledge, this is the first fixed-level completeness result for a spectral-gap certification hierarchy over an infinite family of frustration-free chains: a single finite combinatorial invariant, acyclicity, decides both the thermodynamic spectral gap and the success of the certificate at one universal level. The acyclic direction is proved by an explicit rational certificate, a superpotential built from a topological height and three local corrections, giving delta_LTI(5) >= min{1/48, 1/sqrt(12H)} for a DAG of height H. The cyclic direction is made quantitative by a free-fermion analysis of the invariant winding sectors: directed cycles carry a diffusive lowest mode of energy of order 1/m^2, and the finite-volume gaps of the directed 2- and 3-cycles are computed exactly, 2(1-cos(pi/m)) and 2(1-cos(2pi/m)). The relationship with the PVBS chains of Bachmann and Nachtergaele and with earlier gapped-gapless classifications is discussed explicitly. All computer-assisted statements use exact symbolic arithmetic. The complete reproducibility package (symbolic pipeline, generated blocks with exact characteristic polynomials, Sturm data, LDL^T certificates, SHA-256 digests) is archived separately at https://doi.org/10.5281/zenodo.21790411. The manuscript has been submitted to Reports on Mathematical Physics.
This record contains the preprint and the complete reproducibility package for “A formal finite-size spectral-map hierarchy for free-fermion entanglement”. The work studies the finite-size deformation of the spectral relation between the discrete prolate (Slepian) eigenvalue and the one-particle entanglement energy in a critical free-fermion chain. Using the exact DPSWF representation, Riccati/Dunham analysis and finite-part period calculus, an all-orders formal hierarchy is derived in which the finite-size coefficients satisfyFj=Pj(D)Φ∞F_j=P_j(D)\Phi_\infty, with PjP_j a rational function of the Euler operator D=t∂tD=t\partial_t. The work establishes universal denominator, degree and zero structures for these rational operators, including additional even-shift factors, and derives their Weber/Bernoulli leading behaviour. Independent checks include exact reconstruction of the half-filling Fisher–Hartwig phase polynomials Q20,Q40,Q60,Q80Q_{20},Q_{40},Q_{60},Q_{80}, exact Legendre reduction at the spectral centre, rational operator reconstruction through j=13j=13, and finite-matrix validation of the first two finite-size coefficients. The archive accompanying the manuscript contains the scripts, exact symbolic calculations, numerical data, regression tests and SHA-256 manifests required to reproduce the principal computational claims. The manuscript explicitly distinguishes the proved formal Dunham hierarchy from the still-open uniform physical connection/remainder theorem.
TL;DR — The Core Finding Contrary to the initial expectation that arithmetic structures (e.g., the coprime-to-6 mask or the Möbius mask) generate distinct number-theoretic spectral signatures, this work provides numerical and formally certified evidence that the Non-Ergodic Extended (NEE) phase is entirely governed by the preservation of first-neighbor connectivity (d=1). Suppressing the d=1 hopping channel induces a topological collapse into strong spatial localization (D2≈0.288→0.045, a factor of 6.4), representing a single-particle spatial analogue of Hilbert Space Fragmentation (HSF). Furthermore, the deep arithmetic logic of the Möbius function acts as topological white noise, in compliance with the Möbius Randomness Principle (Sarnak conjecture): since 86.05% of the interaction variance is concentrated in short-range bonds (d≤5), deeper arithmetic channels are swamped by the finite-size GUE noise floor (σGUE∼1/N). Theoretical and Physical Framework Deterministic-stochastic hybrid Hamiltonian. Combines an exact Riemann–von Mangoldt diagonal potential (inverted deterministically via the Lambert WW function) with Power-Law Random Banded Matrix (PRBM) off-diagonal disorder. Sparse hopping constraints. Hopping is filtered by deterministic arithmetic sieves (coprime-to-6 mask Ξ6, square-free Möbius mask Ξμ, Liouville mask Ξλ) and controlled random Bernoulli ensembles. Single-particle Hilbert space fragmentation. Without d=1, adjacent spatial transitions (i→i+1) require higher-order virtual paths (i→i+5→i+1) that suffer severe energy detuning from the fluctuating diagonal potential. The one-dimensional metric graph shatters into decoupled spatial clusters. Coupling variance dominance. The power-law decay (d−1.5 in variance) concentrates 86.05% of the interaction weight in d∈{1,2,3,5}. Deeper arithmetic channels (d≥6) remain buried beneath the finite-size GUE noise floor. Parameter-free operating point. ν=0.75 (exact center of the critical window 0.5<ν<1); local resonance coupling analytically derived as ϵc=π2; Maslov phase 7/8. Mechanized Formal Verification in Lean 4 The algebraic, topological, and connectivity constraints governing the model are certified 100% sorry-free by the Lean 4 kernel (v4.34.1 with Mathlib4), across 13 Level N1 modules (23 theorems, 11 definitions, 34 total verified statements): WheelChannelStructure.lean — Confinement to active chiral sublattices (d≡1,5(mod6)). UnitCellMeasure.lean — Unit cell totient measure (∑d=16Ξ(d)=2 ⟹ φ(6)/6=1/3). ChiralPhaseAbsorption.lean — Invertibility of coprime residues modulo 6. KatoRellichRegime.lean — Self-adjointness domain window (1/2<ν<1). LocalResonanceCoupling.lean — Hybridization resonance condition (ϵc=π2). ChannelDensityContraction.lean — Strict density hierarchy (4/15<1/3<1/2<1). NonErgodicPhaseBound.lean — Non-triviality of the bipartite ceiling (1/4<1). PolyphaseFilterZ6.lean — Complete stopband annihilation for non-coprime channels. FirstNeighborPreservation.lean — Guaranteed base coordination degree (w1=2). DihedralQuantization.lean — Reflection involution and percolation threshold bounds. BipartiteInterferenceBound.lean — Certified upper bound D2≤1/4 under chiral equiprobability. ExpectedDegreeBound.lean — Mean degree lower bound (⟨deg⟩local≥2). FractalDimensionUpperBound.lean — Generalized Jensen inequality for the IPR and universal bound D2≤φ(m)/m. Empirical validation of Lean 4 axioms. Extensive GPU audits up to N=12 000 confirm that the chiral equiprobability axiom (c1=c5=1/2) holds strictly at the ensemble level (⟨W1−W5⟩=−0.000048≈0), with local mass fluctuations decaying monotonically as N→∞. Comprehensive Experimental Validation Matrix Observable Empirical Result Benchmark Physical significance Macroscopic alignment (R2) >0.999999 R2→1 Autonomous Weyl law tracking; zero empirical rescaling Bulk spacing ratio ⟨r⟩ 0.5891±0.0024 GUE 0.5996 / Poisson 0.3863 Intermediate non-ergodic extended statistics SFF ramp exponent γ 0.6086±0.0103 GUE γ=1 Sub-diffusive spectral ramp characteristic of NEE FSS thermodynamic limit D2∞ 0.113±0.003 Anderson D2=0 39σ rejection of Anderson localization Chalker scaling β=2D2 β=0.5549±0.0020 2D2=0.5562±0.0054 0.2σ agreement between transport and fractal support Multifractal curvature ΔD D0−D2=0.730 Ergodic ΔD=0 Strict convexity of Dq for q∈[−3,4]; width Δα=3.726 First-neighbor removal D2=0.0448±0.0009 Preserved: 0.2882 Sixfold collapse into strong localization (HSF) Short-range rescue (d=1) D2=0.2849±0.0007 Unforced: 0.0556 Forcing d=1 restores the NEE phase in random masks Topological pinning (ε=εc) D2no/D2with≈0.17 Healed ratio →1→1 Collapse cannot be overcome at the critical resonance Riemann zeros control (SFF) γzeros=0.94±0.12 GUE γ=1γ=1 Real zeros are ergodic; the NEE ramp is intrinsic to the mask Repository Structure and Reproducibility The codebase is fully vectorized, GPU-accelerated (PyTorch cuSOLVER in complex128), and audited via an automated SHA-256 manifest. The notebook regenerates every figure and table of the manuscript from a fixed random seed (SEED = 42). PRBM_Modular_Lean/ — Standalone Lean 4 (v4.34.1) project containing all 13 verified .lean files and lakefile.lean. Modules 00a–00c — System setup, forensic audit of the 100,000-zero Riemann dataset, and vectorized Hamiltonian engine (complex128). Modules 01–03 — Exact diagonalization at N=10 000; local level statistics P(s) and ⟨r⟩; spectral form factor ensemble averaging (M=100, N=15 000). Modules 04–06 — Channel-density scaling and finite-size scaling; FSS collapse of P(d2,N) across N∈{2000,4000,8000,12000}; AIC/BIC model selection. Modules 07–09 — Anderson transition sweep (ν∈[0.5,3.0]); systematic mask comparison suite; Möbius equivalence and density sweep. Modules 10–12 — Full multifractal spectrum Dq,f(α); microscopic GPU diagonalization at N=12 000; quantum dynamics (MSD, survival probability, Shannon and entanglement entropies). Modules 13–15 — Riemann zeros control SFF; coupling sweep over ε/εc∈[0.2,4.0]; chiral equiprobability audit ⟨Wr⟩ across residue classes. Module 16 — Automated high-resolution vector export (PDF/PNG 300 DPI) and cryptographic manifest generation (MANIFEST_SHA256.txt). Open-Access Dual Licensing Source code (Lean 4, Python, PyTorch): released under the MIT License. Free for academic, educational, and commercial replication. Manuscript, figures, manifests, and data: released under the Creative Commons Attribution 4.0 International License (CC BY 4.0). Declarations Author contributions. Conceptualization, methodology, software, formal analysis, formal verification, investigation, data curation, validation, writing (original draft and revision), visualization, project administration. Competing interests. The author declares no competing interests, financial or otherwise. Funding. No external funding was received for this research. Ethics. Ethical approval was not required, as this research is theoretical and numerical and involves no human participants or animal subjects. Generative AI disclosure. Google Gemini and DeepSeek were used exclusively as auxiliary tools for language editing, adversarial logical review ("red-teaming"), and code debugging. They were not used to produce any original scientific content: all model design, numerical experiments, theoretical derivations, and interpretations are the author's own work. Every AI-assisted output has been reviewed and validated by the author. Scientific Epilogue "In the beginner's mind there are many possibilities, but in the expert's there are few." — Shunyu Suzuki What began as an inquiry into whether number-theoretic structures dictate quantum chaos revealed a simpler, deeper, and more universal physical law: geometry and local connectivity precede arithmetic complexity. The code, formal proofs, and data deposited here are provided to ensure complete auditability, verifiable down to the individual logical inferences of the Lean 4 kernel. Archival snapshot: October 2026 · Certified Level N1 · Built with Lean 4, PyTorch, NumPy, SciPy, and Google Colab. Version: v4 ( submission EPJB-D-26-00793)
A bstract We develop a non-nested Bethe ansatz description of rational 𝔤𝔩 ℓ spin chains in the vector representation. Starting from the quantum spectral curve and the separation-of-variables framework, we derive closed systems of Bethe equations involving only the momentum-carrying Bethe roots. The construction is worked out explicitly for the 𝔤𝔩 3 and 𝔤𝔩 4 spin chains and then generalized to arbitrary rank. A central result of this work is the identification of a recursive hierarchy associated with the fundamental transfer matrices. The hierarchy is generated by regularity conditions of the lower transfer matrices and closes through a universal rank- ℓ equation ℛ ℓ = 0. This equation replaces the final level of the conventional nested Bethe ansatz and eliminates all auxiliary Bethe roots. Consequently, the complete spectral data of an eigenstate are encoded solely in the first Baxter polynomial Q 1 ( u ). We further obtain explicit expressions for the eigenvalues of all fundamental transfer matrices in terms of the momentum-carrying roots alone. The resulting formulation provides a compact characterization of the spectrum of rational 𝔤𝔩 ℓ spin chains and reveals a direct connection between the quantum spectral curve, transfer-matrix fusion relations, and a truncated Q -system underlying the non-nested description. Finally, we investigate the quasi-classical (Gaudin) limit of the non-nested Bethe equations. For the 𝔤𝔩 3 spin chain, we show that the leading non-trivial contribution gives rise to Gaudin equations whose pole-free form naturally defines a scalar third-order 𝔤𝔩 3 oper.
The exact multi-resolvent hierarchy of dense many-body spectra encodes higher-order spectral-weight correlations, but closing it predictively for interacting Hamiltonians remains a challenge. We introduce the multi-resolvent self-consistency (MRSC) equations, which separate an exact algebraic hierarchy from an approximate finite-parameter closure. The exact Feshbach geometric identity organizes r-resolvent cumulants into a ladder over irreducible vertices Gamma^(r), and the projected hierarchy expresses those vertices as functionals of the cumulants. The closure works in finite parameters: a connectivity basis organizes a general Hamiltonian's seed into class amplitudes, and a causal r-fold Stieltjes representation with a moment-field identity reduce moment matching to a finite-dimensional problem closed at a predictive fixed point. On the free-fermion benchmark the tested exact identities are reproduced and the Faddeeva closure is recovered at r=1. In a blind test on the interacting Ising chain, with the exact two-resolvent data withheld, the Hamiltonian-derived closure predicts the tested probes to 0.35%-0.97%. At the observable level the exact two-resolvent sector supplies a sign-correct, energy-resolved correction to the single-resolvent baseline for the off-diagonal eigenstate-thermalization-hypothesis (ETH) variance, of order one relative to it. Closure errors organize hierarchically: a level-by-level deficit decomposition, anchor measurements of the isolatable terms, and an explicit propagation bound. The same moments further yield a diagnostic chain for the window conditions of local rotational invariance -- an exact drift-kernel identity, a proven single-state identifiability boundary, and a transferability census over couplings and realizations -- a finite-order framework, not a proof of universal emergence.
This thesis studies the mathematical structure of quantum Hall transport in lattice systems, with an emphasis on relating mutiple definitions of Hall conductance in different mathematical branches: Geometrically as a bulk Chern number for a Bloch bundle; analytically as an edge spectral flow for a half-space Hamiltonian; and in operator algebra language as a many body charge transport index generated by magnetic flux insertion. The main results of the thesis reveal restrictions imposed on these indices by frustration-free structure, and improved locality estimates for interacting many body systems.The first result concerns frustration free free-Fermion (F 4 ) Hamiltonians. For translation-invariant, strictly local, gapped F4 Hamiltonians on Z 2 , we prove that the bulk index vanishes. More precisely, the two Bloch bundle associated with the image/kernel of the momentum space Hamiltonian is shown to be trivial by an algebraic argument using polynomial modules and a free resolution. Thus a frustration-free free-Fermion model cannot realize a nontrivial integer quantum Hall phase at the level of the bulk Chern index.The second new result is the corresponding edge statement. For a translation-invariant F4 Hamiltonian restricted to a half-plane, we prove that the edge index vanishes. We first identified that frustration free is equivalent to flat ground state band. Detailed analysis of spectral flow of the edge Hamiltonian shows that the edge mode is an analytic function and can be absorbed by the flat band. Consequently, the edge spectral flow across a regular energy in the bulk gap is constant and must equal its trivial value below the spectrum. This establishes, in this setting, that the frustration-free structure rules out nonzero edge transport as well as nonzero bulk transport. The third new result is an exponential clustering theorem for finite-volume quantum spin systems with a possibly degenerate and split ground-state sector. Assuming only a uniform spectral gap above a low-energy spectral patch of sufficiently small width, we prove exponential decay of correlations in the form|⟨Ω, ABΩ⟩ − ⟨Ω, AP BΩ⟩| ≤ C∥P∥1∥A∥∥B∥e −cd(X,Y ),for local observables A and B with disjoint supports. This improves the locality control needed in many body Hall conductance arguments, where previous estimates under comparable hypotheses were superpolynomial. Together, these results clarify how locality and spectral gaps constrain both free-Fermion and interacting formulations of topological transport.