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CsdLean4.LF6.CGLMPQudit

LF6-D (QM side, general d): Ψ_d violates the CGLMP inequality for every d ≥ 2 #

Category: 3-Local (the general-d-intrinsic Bell violation for Ψ_d, the QM-side payoff of the CGLMP infrastructure Mathlib/Probability/CGLMP.lean, extending the d = 3 qutrit violation CGLMPQutrit.cglmp_maxEntangled_qutrit_gt_two to ALL d ≥ 2).

What is proved (general d, no dimension restriction) #

Under the standard CGLMP phase-basis measurements on Ψ_d = maxEntangled d (Alice offsets α₁ = 0, α₂ = 1/2; Bob offsets β₁ = -1/4, β₂ = 1/4), the joint outcome-difference Born probabilities pQM x y c = P(A_x − B_y = c) are computed from the Hilbert space for arbitrary d:

Honest scope #

Reference: Collins, Gisin, Linden, Massar, Popescu, Phys. Rev. Lett. 88, 040404 (2002). specs/lf6-plan.md (LF6-D).

theorem CSD.LF6.CGLMPQudit.dirichlet_kernel (φ : ℝ) (hs : Real.sin (φ / 2) ≠ 0) (n : ℕ) :
‖∑ j ∈ Finset.range n, Complex.exp (↑φ * Complex.I) ^ j‖ ^ 2 = Real.sin (↑n * φ / 2) ^ 2 / Real.sin (φ / 2) ^ 2
noncomputable def CSD.LF6.CGLMPQudit.alphaOff (x : Bool) :

Alice's setting offset α_x: 0 for setting A₁, 1/2 for A₂ (the CGLMP convention — the two settings differ by half a phase step).

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    noncomputable def CSD.LF6.CGLMPQudit.betaOff (y : Bool) :

    Bob's setting offset β_y: -1/4 for B₁, +1/4 for B₂ — the quarter-step staggering against Alice's grid that makes the CGLMP value maximal.

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      noncomputable def CSD.LF6.CGLMPQudit.deltaOff (x y : Bool) :

      The joint offset δ_{xy} = α_x - β_y, the only combination of the two settings the correlation depends on.

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        Interface lemmas (CONVENTIONS §9.1, F2): the values the case splits below keep re-deriving, stated once. Deliberately not @[simp] — existing proofs unfold by name and must not change behaviour.

        Alice's setting offset, x = false branch.

        Alice's setting offset, x = true branch.

        Bob's setting offset, y = false branch.

        Bob's setting offset, y = true branch.

        The joint offset as its defining difference.

        The four joint-offset values, in one statement per setting pair.

        theorem CSD.LF6.CGLMPQudit.sin_sq_pi_delta (x y : Bool) (m : ℤ) :
        Real.sin (Real.pi * (↑m + deltaOff x y)) ^ 2 = 1 / 2
        noncomputable def CSD.LF6.CGLMPQudit.aAngle (d : ℕ) (x : Bool) (k : ZMod d) (j : Fin d) :

        Alice's measurement phase on computational index j for outcome k of setting x: 2π j (k + α_x) / d. The offset α_x is what distinguishes her two settings.

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          noncomputable def CSD.LF6.CGLMPQudit.bAngle (d : ℕ) (y : Bool) (l : ZMod d) (j : Fin d) :

          Bob's measurement phase on computational index j for outcome l of setting y: -2π j (l + β_y) / d. The sign is opposite to Alice's, so a product measurement pairs their phases by difference.

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            theorem CSD.LF6.CGLMPQudit.aAngle_def (d : ℕ) (x : Bool) (k : ZMod d) (j : Fin d) :
            aAngle d x k j = 2 * Real.pi * ↑↑j * (↑k.val + alphaOff x) / ↑d

            Alice's measurement phase, as its defining formula (interface lemma, §9.1).

            theorem CSD.LF6.CGLMPQudit.bAngle_def (d : ℕ) (y : Bool) (l : ZMod d) (j : Fin d) :
            bAngle d y l j = -(2 * Real.pi * ↑↑j * (↑l.val + betaOff y) / ↑d)

            Bob's measurement phase, as its defining formula (interface lemma, §9.1).

            noncomputable def CSD.LF6.CGLMPQudit.aVec (d : ℕ) (x : Bool) (k : ZMod d) :

            Alice's measurement vector for outcome k of setting x: the normalised Fourier vector carrying the phases aAngle.

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              noncomputable def CSD.LF6.CGLMPQudit.bVec (d : ℕ) (y : Bool) (l : ZMod d) :

              Bob's measurement vector for outcome l of setting y: the normalised Fourier vector carrying the phases bAngle.

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                noncomputable def CSD.LF6.CGLMPQudit.outcome (d : ℕ) (x y : Bool) (k l : ZMod d) :

                The joint measurement vector for the outcome pair (k, l) at settings (x, y): the product vector aVec ⊗ bVec on the two-qudit register.

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                  noncomputable def CSD.LF6.CGLMPQudit.bornPair (d : ℕ) (x y : Bool) (k l : ZMod d) :

                  The Born probability of the outcome pair (k, l) at settings (x, y) on the maximally entangled state.

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                    noncomputable def CSD.LF6.CGLMPQudit.baseAngle (d : ℕ) (x y : Bool) (k l : ZMod d) :

                    The joint phase base -2π (k - l + δ_{xy}) / d: the single angle the pair probability depends on, so the correlation is a function of the outcome difference k - l alone.

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                      theorem CSD.LF6.CGLMPQudit.baseAngle_def (d : ℕ) (x y : Bool) (k l : ZMod d) :
                      baseAngle d x y k l = -(2 * Real.pi * (↑k.val - ↑l.val + deltaOff x y) / ↑d)

                      The joint phase base, as its defining formula (interface lemma, §9.1).

                      theorem CSD.LF6.CGLMPQudit.sin_sq_shift (d : ℕ) [NeZero d] (b : ℝ) (t : ℤ) :
                      Real.sin (Real.pi * (b + ↑d * ↑t) / ↑d) ^ 2 = Real.sin (Real.pi * b / ↑d) ^ 2
                      theorem CSD.LF6.CGLMPQudit.sin_denom_ne' (d : ℕ) [NeZero d] (x y : Bool) (m : ℤ) :
                      Real.sin (Real.pi * (↑m + deltaOff x y) / ↑d) ≠ 0
                      theorem CSD.LF6.CGLMPQudit.inner_outcome_collapse (d : ℕ) (x y : Bool) (k l : ZMod d) :
                      inner ℂ (outcome d x y k l) (maxEntangled d) = (↑√↑d)⁻¹ * ∑ i : Fin d, (starRingEnd ℂ) ((outcome d x y k l).ofLp (i, i))
                      theorem CSD.LF6.CGLMPQudit.hconj_term (d : ℕ) (x y : Bool) (k l : ZMod d) (i : Fin d) :
                      (starRingEnd ℂ) ((outcome d x y k l).ofLp (i, i)) = 1 / ↑d * Complex.exp (↑(baseAngle d x y k l) * Complex.I) ^ ↑i
                      theorem CSD.LF6.CGLMPQudit.bornPair_closed (d : ℕ) [NeZero d] (x y : Bool) (k l : ZMod d) :
                      bornPair d x y k l = 1 / (2 * ↑d ^ 3 * Real.sin (Real.pi * (↑k.val - ↑l.val + deltaOff x y) / ↑d) ^ 2)

                      Jordan + reduction infra #

                      theorem CSD.LF6.CGLMPQudit.jordan_sin (x : ℝ) (h0 : 0 ≤ x) (h1 : x ≤ Real.pi / 2) :
                      theorem CSD.LF6.CGLMPQudit.sin_sq_neg (d : ℕ) (r : ℝ) :
                      Real.sin (Real.pi * -r / ↑d) ^ 2 = Real.sin (Real.pi * r / ↑d) ^ 2
                      theorem CSD.LF6.CGLMPQudit.val_congr (d : ℕ) [NeZero d] (c : ZMod d) (n : ℤ) (h : ↑n = c) :
                      ∃ (t : ℤ), ↑c.val = n + ↑d * t
                      theorem CSD.LF6.CGLMPQudit.denom_reduce (d : ℕ) [NeZero d] (c : ZMod d) (n : ℤ) (r δ : ℝ) (hc : ↑n = c) (heq : ↑n + δ = r ∨ ↑n + δ = -r) :
                      Real.sin (Real.pi * (↑c.val + δ) / ↑d) ^ 2 = Real.sin (Real.pi * r / ↑d) ^ 2
                      theorem CSD.LF6.CGLMPQudit.vals_diff_congr (d : ℕ) [NeZero d] (a b : ZMod d) (n : ℤ) (h : ↑n = a - b) :
                      ∃ (t : ℤ), ↑a.val - ↑b.val = n + ↑d * t
                      theorem CSD.LF6.CGLMPQudit.denom_diff_reduce (d : ℕ) [NeZero d] (a b : ZMod d) (n : ℤ) (δ : ℝ) (h : ↑n = a - b) :
                      Real.sin (Real.pi * (↑a.val - ↑b.val + δ) / ↑d) ^ 2 = Real.sin (Real.pi * (↑n + δ) / ↑d) ^ 2

                      pQM and its closed form #

                      noncomputable def CSD.LF6.CGLMPQudit.pQM (d : ℕ) [NeZero d] (x y : Bool) (c : ZMod d) :

                      The quantum correlation P(A - B = c) at settings (x, y): the total Born weight of all outcome pairs whose difference is c. This is the quantity the CGLMP bracket combines.

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                        theorem CSD.LF6.CGLMPQudit.pQM_closed (d : ℕ) [NeZero d] (x y : Bool) (c : ZMod d) :
                        pQM d x y c = 1 / (2 * ↑d ^ 2 * Real.sin (Real.pi * (↑c.val + deltaOff x y) / ↑d) ^ 2)
                        theorem CSD.LF6.CGLMPQudit.pQM_reduce (d : ℕ) [NeZero d] (x y : Bool) (c : ZMod d) (n : ℤ) (r : ℝ) (hc : ↑n = c) (heq : ↑n + deltaOff x y = r ∨ ↑n + deltaOff x y = -r) :
                        pQM d x y c = 1 / (2 * ↑d ^ 2 * Real.sin (Real.pi * r / ↑d) ^ 2)

                        The bracket closed form #

                        noncomputable def CSD.LF6.CGLMPQudit.bracketClosed (d k : ℕ) :

                        The closed form of the k-th CGLMP bracket term on the maximally entangled state: the difference of two 1/sin² weights a quarter-step either side of k. Summing these with the CGLMP coefficients gives the qudit Bell value.

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                          Nonnegativity of coefficients and bracket terms #

                          theorem CSD.LF6.CGLMPQudit.coeff_nonneg (d : ℕ) (hd : 2 ≤ d) (k : ℕ) (hk : k < d / 2) :
                          0 ≤ 1 - 2 * ↑k / (↑d - 1)
                          theorem CSD.LF6.CGLMPQudit.bracketClosed_nonneg (d : ℕ) (hd : 2 ≤ d) (k : ℕ) (hk : k < d / 2) :

                          The k=0 bracket exceeds 2 (the analytic lower bound) #

                          The general-d CGLMP violation and the Bell force #

                          The general-d closed-form CGLMP value for Ψ_d. The CGLMP functional on Ψ_d's Born table is the ⌊d/2⌋-term weighted sum of the Dirichlet-kernel brackets (2/d²)(csc²(π(k+1/4)/d) − csc²(π(k+3/4)/d)), the standard maximally-entangled CGLMP value. Derived (cglmpBracket_closed), not asserted.

                          The general-d CGLMP violation (QM side). For every d ≥ 2, Ψ_d = maxEntangled d violates the CGLMP inequality: its CGLMP value exceeds the local-hidden-variable bound 2. A genuine analytic inequality on the d-dependent Dirichlet-kernel trig sum, proved for ALL d ≥ 2 (the sum dominates its k = 0 term, and that term alone is ≥ 32/π² − 8/9 > 2 uniformly in d). Extends the d = 3 qutrit result CGLMPQutrit.cglmp_maxEntangled_qutrit_gt_two to full dimensional generality.

                          theorem CSD.LF6.CGLMPQudit.no_lhv_realises_maxEntangled_cglmp_d (d : ℕ) [NeZero d] (hd : 2 ≤ d) {Λ : Type u_1} [MeasurableSpace Λ] (μ : MeasureTheory.Measure Λ) [MeasureTheory.IsProbabilityMeasure μ] (A B : Bool → Λ → ZMod d) (hA : ∀ (x : Bool), Measurable (A x)) (hB : ∀ (y : Bool), Measurable (B y)) (hRep : ProbabilityTheory.CGLMP.lhvTable μ A B = pQM d) :