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

Andrew Stewart Caldin

Published Sep 25, 2026• 0 citations

Abstract

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.com

DOI: 10.5281/zenodo.22951728

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

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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.com

Jul 24, 20260 citations

Tsirelson Bounds via Geometric Algebra: CHSH Violation Ratio √2 — E8 Intelligence Research

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

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D4 Symmetry and the 45° Origin of Tsirelson's Bound — E8 Intelligence Research

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

Andrew Stewart Caldin

Published Sep 25, 2026• 0 citations

Publisher

Abstract

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.com

DOI: 10.5281/zenodo.22951728

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

Andrew Stewart Caldin

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.comFINDING: 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

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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

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Tsirelson Bounds via Geometric Algebra: CHSH Violation Ratio √2 — E8 Intelligence Research

Andrew Stewart Caldin

FINDING: The only substantive result is the arXiv paper on Tsirelson bounds derived via geometric algebra — the rest are unrelated video titles (Python, lab software, condensed matter talks) with no mathematical content. | MATH: The paper (arXiv:2007.05301v3) re-derives the CHSH inequality and its quantum violation using geometric (Clifford) algebra. Key constants: classical CHSH bound = 2; quantum Tsirelson bound = 2√2 ≈ 2.828. The violation ratio is √2. No explicit golden-ratio or base-60 constants appear in the abstract. | CONNECTION: The Tsirelson bound 2√2 relates to the octonionic/E8 structure only if the paper explicitly links geometric algebra to root systems — the abstract does not state this. However, 2√2 = √(2·2) and its square = 8, which is the dimension of the octonions and the rank of E8. The ratio √2 is a crystallographic symmetry element (rotation by 45° in 2D, and appears in the Weyl group of B2/C2). No 0.382, 0.618, 0.786, 1.618, or 2.618 appear in the evidence. | DEP Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: The only substantive result is the arXiv paper on Tsirelson bounds derived via geometric algebra — the rest are unrelated video titles (Python, lab software, condensed matter talks) with no mathematical content. | MATH: The paper (arXiv:2007.05301v3) re-derives the CHSH inequality and its quantum violation using geometric (Clifford) algebra. Key constants: classical CHSH bound = 2; quantum Tsirelson bound = 2√2 ≈ 2.828. The violation ratio is √2. No explicit golden-ratio or base-60 constants appear in the abstract. | CONNECTION: The Tsirelson bound 2√2 relates to the octonionic/E8 structure only if the paper explicitly links geometric algebra to root systems — the abstract does not state this. However, 2√2 = √(2·2) and its square = 8, which is the dimension of the octonions and the rank of E8. The ratio √2 is a crystallographic symmetry element (rotation by 45° in 2D, and appears in the Weyl group of B2/C2). No 0.382, 0.618, 0.786, 1.618, or 2.618 appear in the evidence. | DEP Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

Sep 30, 20260 citations

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

Andrew Stewart Caldin

FINDING: Tsirelson's bound (2√2 ≈ 2.828) emerges from the geometry of the Bloch sphere and SO(3) rotations, not from ad hoc quantum postulates. | MATH: CHSH inequality classical bound = 2; quantum maximum = 2√2. Derivation via Bloch vectors: for observables A(a), B(b) with outcomes ±1, correlation E(a,b) = a·b (for spin-1/2). CHSH expression S = E(a,b) + E(a,b') + E(a',b) − E(a',b'). Maximizing over unit vectors a,a',b,b' ∈ S² yields S_max = 2√2. This is equivalent to the maximum of |a·b + a·b' + a'·b − a'·b'| = 2√2, attained when the four vectors form a regular tetrahedron (tetrahedral angle 109.47°, cos⁻¹(−1/3)). | CONNECTION: The tetrahedron is a root system of A₃ (SU(4) Weyl group), and its vertices correspond to the 4 vertices of the 3-simplex. The ratio 2√2/2 = √2 ≈ 1.414 relates to the diagonal of a square — a crystallographic ratio. The Bloch sphere's SO(3) symmetry group has the same Lie algebra as SU(2), whose root system is A₁. The tetrahedral configuration is the maximal sy Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: Tsirelson's bound (2√2 ≈ 2.828) emerges from the geometry of the Bloch sphere and SO(3) rotations, not from ad hoc quantum postulates. | MATH: CHSH inequality classical bound = 2; quantum maximum = 2√2. Derivation via Bloch vectors: for observables A(a), B(b) with outcomes ±1, correlation E(a,b) = a·b (for spin-1/2). CHSH expression S = E(a,b) + E(a,b') + E(a',b) − E(a',b'). Maximizing over unit vectors a,a',b,b' ∈ S² yields S_max = 2√2. This is equivalent to the maximum of |a·b + a·b' + a'·b − a'·b'| = 2√2, attained when the four vectors form a regular tetrahedron (tetrahedral angle 109.47°, cos⁻¹(−1/3)). | CONNECTION: The tetrahedron is a root system of A₃ (SU(4) Weyl group), and its vertices correspond to the 4 vertices of the 3-simplex. The ratio 2√2/2 = √2 ≈ 1.414 relates to the diagonal of a square — a crystallographic ratio. The Bloch sphere's SO(3) symmetry group has the same Lie algebra as SU(2), whose root system is A₁. The tetrahedral configuration is the maximal sy Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

Sep 21, 20260 citations

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

Oct 13, 20260 citations

D4 Symmetry and the 45° Origin of Tsirelson's Bound — E8 Intelligence Research

Andrew Stewart Caldin

FINDING: The CHSH-Bell inequality's quantum bound (Tsirelson bound) is exactly 2√2, and its geometric origin lies in the D4 square-lattice symmetry of the qubit Bloch sphere, where the maximal violation corresponds to measuring along axes rotated by 45° (π/4) — the same angle that generates the square lattice's rotational symmetry. MATH: - CHSH parameter: $S = E(a,b) + E(a,b') + E(a',b) - E(a',b')$ - Local hidden variable bound: $S \leq 2$ - Quantum (Tsirelson) bound: $S_{\text{max}} = 2\sqrt{2} \approx 2.828$ - Optimal measurement angles: $\theta = \pi/4$ (45°) between Alice's and Bob's settings - Qubit correlation: $E(\theta) = \cos(2\theta)$ → at $\theta = \pi/4$ , $\cos(\pi/2) = 0$ for one term, but the combination yields $2\sqrt{2}$ - D4 symmetry: order 8 dihedral group — rotations by $\pi/2$ and reflections; the 4 measurement settings form a square on the Bloch circle, with vertices at $0, \pi/4, \pi/2, 3\pi/4$ relative to the r Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.comFINDING: The CHSH-Bell inequality's quantum bound (Tsirelson bound) is exactly 2√2, and its geometric origin lies in the D4 square-lattice symmetry of the qubit Bloch sphere, where the maximal violation corresponds to measuring along axes rotated by 45° (π/4) — the same angle that generates the square lattice's rotational symmetry. MATH: - CHSH parameter: $ S = E(a,b) + E(a,b') + E(a',b) - E(a',b') $ - Local hidden variable bound: $ S \leq 2 $ - Quantum (Tsirelson) bound: $ S_{\text{max}} = 2\sqrt{2} \approx 2.828 $ - Optimal measurement angles: $ \theta = \pi/4 $ (45°) between Alice's and Bob's settings - Qubit correlation: $ E(\theta) = \cos(2\theta) $ → at $ \theta = \pi/4 $, $ \cos(\pi/2) = 0 $ for one term, but the combination yields $ 2\sqrt{2} $ - D4 symmetry: order 8 dihedral group — rotations by $ \pi/2 $ and reflections; the 4 measurement settings form a square on the Bloch circle, with vertices at $ 0, \pi/4, \pi/2, 3\pi/4 $ relative to the r Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

Oct 2, 20260 citations

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

S = E(a,b) + E(a,b') + E(a',b) - E(a',b')

- Local hidden variable bound:

S \leq 2

- Quantum (Tsirelson) bound:

S_{\text{max}} = 2\sqrt{2} \approx 2.828

- Optimal measurement angles:

\theta = \pi/4

(45°) between Alice's and Bob's settings - Qubit correlation:

E(\theta) = \cos(2\theta)

→ at

\theta = \pi/4

\cos(\pi/2) = 0

for one term, but the combination yields

2\sqrt{2}

- D4 symmetry: order 8 dihedral group — rotations by

\pi/2

and reflections; the 4 measurement settings form a square on the Bloch circle, with vertices at

0, \pi/4, \pi/2, 3\pi/4

relative to the r Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com