Coherence Noise Across Scales: Linking Quantum Circuit Decoherence to Cosmological Dark Energy Through a Com- mon Noise Parameter

Radial Coherential Dynamics (RCD) posits a scalar coherence field 𝒞 whose deco- herence drives phenomena from quantum circuit noise to cosmological dark energy. Two mature but disconnected modules exist: (i) a cross-platform analysis of GHZ state fidelity under dephasing-dominated noise, where a Lindblad model with local and col- lective dephasing channels produces a crossover at 𝑁⋆ ≈ 𝛾local/𝛾𝑐; and (ii) a cosmo- logical effective field theory in which a Caldeira–Leggett bath stabilizes a hilltop dark energy potential, with effective coefficients derived from an Ohmic spectral density parametrized by (𝜂, 𝜆, ΛUV). Here we construct a minimal phenomenological bridge between these modules by introducing a single dimensionless parameter 𝜀 ≡ 𝛾𝑐/𝛾local — the fraction of collective-to-local noise — and proposing, as an explicit ansatz, that 𝜀 is approximately scale-invariant. Under this ansatz, the laboratory measurement 𝑁⋆ ≈ 15–20 on IonQ Forte fixes 𝜀 ∈ [0.05, 0.07], which constrains the cosmological bath coupling 𝜂𝜆 to a narrow window. Conversely, the cosmological requirement of controlled backreaction imposes an upper bound 𝜀 < 𝜀max, predicting a lower bound 𝑁⋆ > 1/𝜀max testable in future multi-qubit experiments. For the benchmark param- eters of the HDE series, the three conditions (stabilization, backreaction, and QC data) overlap in the narrow window 𝜀 ∈ [0.05, 0.07], yielding a dark energy equation of state 𝑤0 ≈ −0.987, consistent with current DESI constraints. The bridge is explic- itly falsifiable: non-overlapping 𝜀 windows from QC and cosmology would refute the universal noise ansatz independently of the validity of either module.