theorem
proved
linkRate_succ
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IndisputableMonolith.Engineering.CoherenceProtectedQKDLinkBudget on GitHub at line 52.
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49 have h_R_pos : (0 : ℝ) < R_0 := by unfold R_0; norm_num
50 exact div_lt_div_of_pos_left h_R_pos hp1 h_pow
51
52theorem linkRate_succ (n : ℕ) :
53 linkRate (n + 1) = linkRate n / phi := by
54 unfold linkRate
55 rw [pow_succ]
56 field_simp
57
58/-! ## §2. Attenuation factor per L_φ -/
59
60/-- Per-rung attenuation factor `= 1/φ ≈ 0.618`. -/
61def attenuationPerRung : ℝ := 1 / phi
62
63theorem attenuationPerRung_pos : 0 < attenuationPerRung :=
64 div_pos one_pos phi_pos
65
66theorem attenuationPerRung_lt_one : attenuationPerRung < 1 := by
67 unfold attenuationPerRung
68 rw [div_lt_one phi_pos]; exact one_lt_phi
69
70theorem attenuationPerRung_band :
71 (0.617 : ℝ) < attenuationPerRung ∧ attenuationPerRung < 0.622 := by
72 unfold attenuationPerRung
73 have h1 := phi_gt_onePointSixOne
74 have h2 := phi_lt_onePointSixTwo
75 refine ⟨?_, ?_⟩
76 · rw [lt_div_iff₀ phi_pos]; linarith
77 · rw [div_lt_iff₀ phi_pos]; linarith
78
79/-! ## §3. Master certificate -/
80
81structure CoherenceProtectedQKDLinkBudgetCert where
82 rate_zero : linkRate 0 = R_0