Driven Radical Motion Enhances Cryptochrome Magnetoreception: Toward Live Quantum Sensing

The mechanism underlying magnetoreception has long eluded explanation. A popular hypothesis attributes this sense to the quantum coherent spin dynamics and spin-selective recombination reactions of radical pairs in the protein cryptochrome. However, concerns about the validity of the hypothesis have been raised because unavoidable inter-radical interactions, such as the strong electron–electron dipolar coupling, appear to suppress its sensitivity. We demonstrate that sensitivity can be restored by driving the spin system through a modulation of the inter-radical distance. It is shown that this dynamical process markedly enhances geomagnetic field sensitivity in strongly coupled radical pairs via Landau–Zener–Stückelberg–Majorana transitions between singlet and triplet states. These findings suggest that a “live” harmonically driven magnetoreceptor can be more sensitive than its “dead” static counterpart.