Geometric Protection of Spin-Correlated Radical Pairs: A Relational Model for Cryptochrome Magnetoreception Lifetimes
Year: 2026
Type: preprint
Abstract: Migratory birds detect the Earth’s magnetic field with remarkable precision using a quantum process in retinal cryptochrome proteins. We review the observational and experimental evidence supporting the radical-pair mechanism and propose a simple dynamical model that augments the standard radical-pair Hamiltonian with a minimal geometric protection term. This term is modulated by consecutive Fibonacci numbers whose ratios converge to the golden ratio ϕ = (1 + √5)/2 ≈ 1.618. Numerical integration and analytical fixed-point analysis show that the protection term naturally stabilizes singlet–triplet coherence lifetimes and optimizes magnetic sensitivity at geomagnetic field strengths and inclinations observed in nature. The model is fully classical, self-contained, and provides a new quantitative explanation for the robustness of avian magnetoreception. It offers the first empirical hint of a universal geometric principle governing quantum coherence in biological systems.
Author: Garrido, Daphne
Language: English
Subfield: Biophysics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7160555626
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