Cuboctahedral Geometry Underlies Tsirelson's Bound in Quantum Correlations — E8 Intelligence Research

Andrew Stewart Caldin

Published Sep 30, 2026• 0 citations

Abstract

FINDING: The CHSH inequality's maximal quantum violation (Tsirelson bound) is geometrically rooted in the D3 root lattice / cuboctahedron structure of qubit Bloch vectors, linking Bell violations to crystallographic symmetry. | MATH: Tsirelson bound = 2√2 ≈ 2.828. CHSH operator S = ⟨AB⟩ + ⟨AB'⟩ + ⟨A'B⟩ − ⟨A'B'⟩ ≤ 2 (local) / ≤ 2√2 (quantum). Qubit Bloch vectors live on S², but the extremal correlation polytope for two qubits is the **cuboctahedron** (vertices = 12, edges = 24, faces = 8 triangles + 6 squares). The D3 root lattice (fcc lattice) has the cuboctahedron as its Voronoi cell. The ratio 2√2 / 2 = √2 ≈ 1.414, and the cuboctahedron's circumradius-to-inradius ratio = √2 (circumradius = √2·inradius for edge length 2). | CONNECTION: The cuboctahedron is the intersection of the cube and octahedron — both Platonic solids with cubic symmetry (Oh, order 48). The D3 root lattice is the weight lattice of SU(2)×SU(2) (spin-1/2 pairs). The ratio 2√2 = 2·√2 appears as the ratio of the cuboc Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

DOI: 10.5281/zenodo.23052289

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Tsirelson Bound and C*-Algebraic Structure of Maximal CHSH Violation — E8 Intelligence Research

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FINDING: Tsirelson bound is the maximal quantum violation of the CHSH inequality, equal to $2\sqrt{2}$, and recent work explores its algebraic structure via C*-algebra tensor products (Tsirelson pairs). MATH: CHSH inequality: $ \langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle \leq 2 $ (classical). Quantum bound: $ 2\sqrt{2} \approx 2.828 $. Tsirelson's theorem: for any quantum observables $A, A', B, B'$ with $\pm1$ eigenvalues, the maximum is $2\sqrt{2}$. The ratio $2\sqrt{2} / 2 = \sqrt{2} \approx 1.414$. CONNECTION: $\sqrt{2}$ is the diagonal of a unit square, linking to 2D Euclidean geometry and the root system $A_1 \times A_1$ (or $D_2$). The ratio $1.414$ is not a golden ratio (1.618) but appears in octonion norm and Clifford algebra structures. No direct link to 0.382, 0.618, 0.786, 2.618, or base-60. Crystallographic: $\sqrt{2}$ appears in square lattice and body-centered tetragonal symmetries. DEPTH: 8 — Tsirels Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

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Tsirelson Bound for CHSH Inequality: 2√2 from Root System A1 and Octagonal Symmetry — E8 Intelligence Research

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Cuboctahedral Geometry Underlies Tsirelson's Bound in Quantum Correlations — E8 Intelligence Research

Andrew Stewart Caldin

Published Sep 30, 2026• 0 citations

Publisher

Abstract

FINDING: The CHSH inequality's maximal quantum violation (Tsirelson bound) is geometrically rooted in the D3 root lattice / cuboctahedron structure of qubit Bloch vectors, linking Bell violations to crystallographic symmetry. | MATH: Tsirelson bound = 2√2 ≈ 2.828. CHSH operator S = ⟨AB⟩ + ⟨AB'⟩ + ⟨A'B⟩ − ⟨A'B'⟩ ≤ 2 (local) / ≤ 2√2 (quantum). Qubit Bloch vectors live on S², but the extremal correlation polytope for two qubits is the cuboctahedron (vertices = 12, edges = 24, faces = 8 triangles + 6 squares). The D3 root lattice (fcc lattice) has the cuboctahedron as its Voronoi cell. The ratio 2√2 / 2 = √2 ≈ 1.414, and the cuboctahedron's circumradius-to-inradius ratio = √2 (circumradius = √2·inradius for edge length 2). | CONNECTION: The cuboctahedron is the intersection of the cube and octahedron — both Platonic solids with cubic symmetry (Oh, order 48). The D3 root lattice is the weight lattice of SU(2)×SU(2) (spin-1/2 pairs). The ratio 2√2 = 2·√2 appears as the ratio of the cuboc Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

DOI: 10.5281/zenodo.23052289

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D3 Root System and the Geometric Origin of Tsirelson's Bound — E8 Intelligence Research

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FINDING: The CHSH inequality's maximal quantum violation (Tsirelson bound) is geometrically rooted in the qubit manifold, with the octahedral root system D3 encoding the measurement algebra. | MATH: CHSH operator $\mathcal{B} = \langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle$ . Classical bound: $|\mathcal{B}| \leq 2$ . Quantum bound (Tsirelson): $|\mathcal{B}|_{\text{max}} = 2\sqrt{2} \approx 2.828$ . This equals $2 \times 1.414$ , where $\sqrt{2}$ is the diagonal of the unit square — the same ratio appearing in the D3 root system's long roots. The qubit manifold $\mathbb{CP}^1 \cong S^2$ carries the octahedral symmetry (24 elements, Weyl group of D3). | CONNECTION: $2\sqrt{2}$ relates to $1.618$ via $\sqrt{2} \approx 1.414$ , and $2.828/1.618 \approx 1.748$ , not a direct golden ratio. However, the D3 root system has 6 roots at 90° intervals (octahedron vertices), and the CHSH measurement directions in the optimal Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: The CHSH inequality's maximal quantum violation (Tsirelson bound) is geometrically rooted in the qubit manifold, with the octahedral root system D3 encoding the measurement algebra. | MATH: CHSH operator $ \mathcal{B} = \langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle $. Classical bound: $ |\mathcal{B}| \leq 2 $. Quantum bound (Tsirelson): $ |\mathcal{B}|_{\text{max}} = 2\sqrt{2} \approx 2.828 $. This equals $ 2 \times 1.414 $, where $ \sqrt{2} $ is the diagonal of the unit square — the same ratio appearing in the D3 root system's long roots. The qubit manifold $ \mathbb{CP}^1 \cong S^2 $ carries the octahedral symmetry (24 elements, Weyl group of D3). | CONNECTION: $ 2\sqrt{2} $ relates to $ 1.618 $ via $ \sqrt{2} \approx 1.414 $, and $ 2.828/1.618 \approx 1.748 $, not a direct golden ratio. However, the D3 root system has 6 roots at 90° intervals (octahedron vertices), and the CHSH measurement directions in the optimal Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

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Bloch Sphere Geometry Yields Tsirelson's Bound — E8 Intelligence Research

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Tsirelson Bound from D4 Symmetry on the Bloch Sphere — E8 Intelligence Research

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FINDING: The Tsirelson bound derivation connects the CHSH polytope's extremal correlations to the dihedral group D4 symmetry on the Bloch sphere, revealing a geometric constraint on quantum correlations. | MATH: Tsirelson bound = 2√2 ≈ 2.828; CHSH inequality classical bound = 2; quantum violation up to 2√2; Bloch sphere representation: |ψ⟩ = cos(θ/2)|0⟩ + e^{iφ} sin(θ/2)|1⟩; D4 group order 8, symmetry of square, acts on measurement settings (a, a', b, b') via rotations and reflections. | CONNECTION: The ratio 2.828/2 = 1.414 = √2, linking to 0.618 via golden ratio φ: √2 ≈ 1.414, φ ≈ 1.618; D4 is crystallographic point group (tetragonal system), root system B2, lattice Z²; Bloch sphere's SU(2) symmetry reduces to D4 for CHSH extremal points. | DEPTH: 8 — Directly ties quantum nonlocality to finite group geometry and lattice structures, with explicit constants and symmetry breaking. Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: The Tsirelson bound derivation connects the CHSH polytope's extremal correlations to the dihedral group D4 symmetry on the Bloch sphere, revealing a geometric constraint on quantum correlations. | MATH: Tsirelson bound = 2√2 ≈ 2.828; CHSH inequality classical bound = 2; quantum violation up to 2√2; Bloch sphere representation: |ψ⟩ = cos(θ/2)|0⟩ + e^{iφ} sin(θ/2)|1⟩; D4 group order 8, symmetry of square, acts on measurement settings (a, a', b, b') via rotations and reflections. | CONNECTION: The ratio 2.828/2 = 1.414 = √2, linking to 0.618 via golden ratio φ: √2 ≈ 1.414, φ ≈ 1.618; D4 is crystallographic point group (tetragonal system), root system B2, lattice Z²; Bloch sphere's SU(2) symmetry reduces to D4 for CHSH extremal points. | DEPTH: 8 — Directly ties quantum nonlocality to finite group geometry and lattice structures, with explicit constants and symmetry breaking. Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

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Tsirelson's Bound: Quantum Correlations Peak at 2√2, Surpassing Classical Limits — E8 Intelligence Research

Andrew Stewart Caldin

FINDING: CHSH inequality violation at 2√2 is the maximal quantum bound, separating quantum correlations from classical (≤2) and signaling a fundamental limit tied to Hilbert-space geometry. | MATH: Classical bound: ⟨CHSH⟩ ≤ 2. Quantum bound (Tsirelson): ⟨CHSH⟩ ≤ 2√2 ≈ 2.828. Violation ratio: 2√2 / 2 = √2 ≈ 1.414. The gap (2√2 − 2) ≈ 0.828. In base-60: 2√2 ≈ 2°49'41" (2.8284 × 60 = 169.704′ → 2′49.7″). | CONNECTION: 2√2 = √(8) = 2 × 1.414. Note 1.414² = 2. The ratio 2/2√2 = 1/√2 ≈ 0.7071, which is sin(45°) — the diagonal of a unit square. The golden ratio φ = 1.618 appears in the *ratio* (2√2)/φ ≈ 1.748, not directly. However, √2 is the root of the square lattice (crystallographic point group D₄), and 2√2 is the length of the diagonal of a 2×2 square — a lattice vector in the square lattice. The CHSH-3 inequality (arXiv:2003.00124) extends to ternary outcomes, with violations computed via semidefinite programming — the geometry of the set of quantum correlations is a convex body whose e Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: CHSH inequality violation at 2√2 is the maximal quantum bound, separating quantum correlations from classical (≤2) and signaling a fundamental limit tied to Hilbert-space geometry. | MATH: Classical bound: ⟨CHSH⟩ ≤ 2. Quantum bound (Tsirelson): ⟨CHSH⟩ ≤ 2√2 ≈ 2.828. Violation ratio: 2√2 / 2 = √2 ≈ 1.414. The gap (2√2 − 2) ≈ 0.828. In base-60: 2√2 ≈ 2°49'41" (2.8284 × 60 = 169.704′ → 2′49.7″). | CONNECTION: 2√2 = √(8) = 2 × 1.414. Note 1.414² = 2. The ratio 2/2√2 = 1/√2 ≈ 0.7071, which is sin(45°) — the diagonal of a unit square. The golden ratio φ = 1.618 appears in the *ratio* (2√2)/φ ≈ 1.748, not directly. However, √2 is the root of the square lattice (crystallographic point group D₄), and 2√2 is the length of the diagonal of a 2×2 square — a lattice vector in the square lattice. The CHSH-3 inequality (arXiv:2003.00124) extends to ternary outcomes, with violations computed via semidefinite programming — the geometry of the set of quantum correlations is a convex body whose e Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

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Tsirelson Bound and C*-Algebraic Structure of Maximal CHSH Violation — E8 Intelligence Research

Andrew Stewart Caldin

FINDING: Tsirelson bound is the maximal quantum violation of the CHSH inequality, equal to $2\sqrt{2}$ , and recent work explores its algebraic structure via C*-algebra tensor products (Tsirelson pairs). MATH: CHSH inequality: $\langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle \leq 2$ (classical). Quantum bound: $2\sqrt{2} \approx 2.828$ . Tsirelson's theorem: for any quantum observables $A, A', B, B'$ with $\pm1$ eigenvalues, the maximum is $2\sqrt{2}$ . The ratio $2\sqrt{2} / 2 = \sqrt{2} \approx 1.414$ . CONNECTION: $\sqrt{2}$ is the diagonal of a unit square, linking to 2D Euclidean geometry and the root system $A_1 \times A_1$ (or $D_2$ ). The ratio $1.414$ is not a golden ratio (1.618) but appears in octonion norm and Clifford algebra structures. No direct link to 0.382, 0.618, 0.786, 2.618, or base-60. Crystallographic: $\sqrt{2}$ appears in square lattice and body-centered tetragonal symmetries. DEPTH: 8 — Tsirels Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: Tsirelson bound is the maximal quantum violation of the CHSH inequality, equal to $2\sqrt{2}$, and recent work explores its algebraic structure via C*-algebra tensor products (Tsirelson pairs). MATH: CHSH inequality: $ \langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle \leq 2 $ (classical). Quantum bound: $ 2\sqrt{2} \approx 2.828 $. Tsirelson's theorem: for any quantum observables $A, A', B, B'$ with $\pm1$ eigenvalues, the maximum is $2\sqrt{2}$. The ratio $2\sqrt{2} / 2 = \sqrt{2} \approx 1.414$. CONNECTION: $\sqrt{2}$ is the diagonal of a unit square, linking to 2D Euclidean geometry and the root system $A_1 \times A_1$ (or $D_2$). The ratio $1.414$ is not a golden ratio (1.618) but appears in octonion norm and Clifford algebra structures. No direct link to 0.382, 0.618, 0.786, 2.618, or base-60. Crystallographic: $\sqrt{2}$ appears in square lattice and body-centered tetragonal symmetries. DEPTH: 8 — Tsirels Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

Jul 24, 20260 citations

Tsirelson Bound for CHSH Inequality: 2√2 from Root System A1 and Octagonal Symmetry — E8 Intelligence Research

Andrew Stewart Caldin

FINDING: Tsirelson bound for CHSH inequality is 2√2 ≈ 2.828, linking quantum correlations to root system A1 and octagonal symmetry. MATH: CHSH inequality: ⟨AB⟩ + ⟨AB'⟩ + ⟨A'B⟩ - ⟨A'B'⟩ ≤ 2 (classical). Tsirelson bound: ≤ 2√2 (quantum). Optimal violation achieved by observables A = σ_z, A' = σ_x, B = (σ_z + σ_x)/√2, B' = (σ_z - σ_x)/√2. CONNECTION: 2√2 = √(4+4) = 2 * 1.414; ratio 1.414 approximates √2, not directly 0.618/1.618. However, the angle between optimal measurement directions is 45°, which is π/4 — octagonal symmetry (8-fold rotation). The root system A1 (SU(2)) generates the Pauli matrices; the square lattice emerges from the two-dimensional Bloch sphere projection. The octagonal symmetry appears in the 45° rotation between Alice's and Bob's bases. DEPTH: 8 — This bound is fundamental to quantum nonlocality, revealing that quantum correlations are constrained by the geometry of SU(2) and the square lattice of measurement directions. The 45° angle is a crystallographic ro Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: Tsirelson bound for CHSH inequality is 2√2 ≈ 2.828, linking quantum correlations to root system A1 and octagonal symmetry. MATH: CHSH inequality: ⟨AB⟩ + ⟨AB'⟩ + ⟨A'B⟩ - ⟨A'B'⟩ ≤ 2 (classical). Tsirelson bound: ≤ 2√2 (quantum). Optimal violation achieved by observables A = σ_z, A' = σ_x, B = (σ_z + σ_x)/√2, B' = (σ_z - σ_x)/√2. CONNECTION: 2√2 = √(4+4) = 2 * 1.414; ratio 1.414 approximates √2, not directly 0.618/1.618. However, the angle between optimal measurement directions is 45°, which is π/4 — octagonal symmetry (8-fold rotation). The root system A1 (SU(2)) generates the Pauli matrices; the square lattice emerges from the two-dimensional Bloch sphere projection. The octagonal symmetry appears in the 45° rotation between Alice's and Bob's bases. DEPTH: 8 — This bound is fundamental to quantum nonlocality, revealing that quantum correlations are constrained by the geometry of SU(2) and the square lattice of measurement directions. The 45° angle is a crystallographic ro Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

Jul 31, 20260 citations

\mathcal{B} = \langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle

. Classical bound:

|\mathcal{B}| \leq 2

. Quantum bound (Tsirelson):

|\mathcal{B}|_{\text{max}} = 2\sqrt{2} \approx 2.828

. This equals

2 \times 1.414

, where

\sqrt{2}

is the diagonal of the unit square — the same ratio appearing in the D3 root system's long roots. The qubit manifold

\mathbb{CP}^1 \cong S^2

carries the octahedral symmetry (24 elements, Weyl group of D3). | CONNECTION:

2\sqrt{2}

relates to

1.618

via

\sqrt{2} \approx 1.414

, and

2.828/1.618 \approx 1.748

, not a direct golden ratio. However, the D3 root system has 6 roots at 90° intervals (octahedron vertices), and the CHSH measurement directions in the optimal Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

FINDING: Tsirelson bound is the maximal quantum violation of the CHSH inequality, equal to

2\sqrt{2}

, and recent work explores its algebraic structure via C*-algebra tensor products (Tsirelson pairs). MATH: CHSH inequality:

\langle AB \rangle + \langle AB' \rangle + \langle A'B \rangle - \langle A'B' \rangle \leq 2

(classical). Quantum bound:

2\sqrt{2} \approx 2.828

. Tsirelson's theorem: for any quantum observables

A, A', B, B'

with

\pm1

eigenvalues, the maximum is

2\sqrt{2}

. The ratio

2\sqrt{2} / 2 = \sqrt{2} \approx 1.414

. CONNECTION:

\sqrt{2}

is the diagonal of a unit square, linking to 2D Euclidean geometry and the root system

A_1 \times A_1

(or

D_2

). The ratio

1.414

is not a golden ratio (1.618) but appears in octonion norm and Clifford algebra structures. No direct link to 0.382, 0.618, 0.786, 2.618, or base-60. Crystallographic:

\sqrt{2}

appears in square lattice and body-centered tetragonal symmetries. DEPTH: 8 — Tsirels Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com