A Coherence‑Gated Coupling Mechanism in Driven Quantum‑Fluctuating Biological Systems

This preprint presents a speculative but fully falsifiable physical mechanism by which biological structures—specifically neuronal microtubules—could exhibit coherence‑gated sensitivity to weak external fields. The model treats tubulin dimers as driven open quantum systems with THz‑scale electric dipole transitions, coupled through an effective Ising‑like interaction. A transverse coherence measure, \ (\), is introduced as a gating variable that modulates the strength of a phenomenological interaction between a coarse‑grained order parameter \ (\) and an external field \ (\). When coherence is present (\ (> 0\) ), the system is sensitive to \ (\) ; when coherence is lost (\ (0\) ), the coupling shuts off. The manuscript derives the conditions under which coherent transport along microtubules is possible, identifying the key requirement \ (J > \), where \ (J\) is the dipole–dipole coupling and \ (\) is the environmental dephasing rate. Using literature‑based estimates, the work establishes a clear falsification criterion: if microtubule dephasing remains \ (10^11–10^12\, s^-1\) at physiological temperature, the proposed mechanism cannot operate. A full Lindblad‑based derivation of the steady‑state coherence \ (ss\) is provided, along with a two‑spin extension showing that the key scaling \ (ss 1/\) is robust to inter‑spin coupling. The manuscript also includes a quantitative signal‑to‑noise estimate demonstrating that naturally occurring fields (e. g. , geomagnetic or dark‑matter‑like backgrounds) are too weak to detect, while laboratory‑generated AC magnetic fields can induce measurable LFP‑scale modulations. Finally, the paper proposes an experimentally feasible test using cortical slices, weak AC magnetic fields, and anesthetic‑induced modulation of \ (\). A positive result would indicate coherence‑gated sensitivity to weak perturbations; a null result, combined with independent measurements of \ (\), would falsify the model. This preprint is intended as a rigorous, testable contribution to quantum biology and biophysical neuroscience. It makes no claims regarding consciousness and focuses solely on physical mechanisms and measurable electrophysiological consequences. Keywords: quantum biology, microtubules, open quantum systems, decoherence, Lindblad dynamics, local field potential, coherence gating, biophysics, THz dipole transitions, anesthetics, cortical slices, signal‑to‑noise ratio