Chirality-bolstered quantum Zeno effect enhances radical pair-based magnetoreception

TL;DR

This study reveals that the chirality-induced spin selectivity (CISS) effect enhances magnetic sensitivity in radical pair reactions by inducing spin polarization and reinforcing the quantum Zeno effect, with implications for understanding avian magnetoreception.

Contribution

It systematically analyzes how CISS influences radical pair magnetoreception, demonstrating that spin polarization, not coherence, enhances sensitivity through the quantum Zeno effect, and provides a unified modeling scheme.

Findings

CISS-induced spin polarization significantly enhances magnetic sensitivity.

CISS-generated spin coherence does not notably improve sensitivity.

A unified interpolation scheme for CISS-influenced dynamics is proposed.

Abstract

Radical pairs in the flavoprotein cryptochrome are central to various magnetically sensitive biological processes, including the proposed mechanism of avian magnetoreception. Cryptochrome's molecular chirality has been hypothesized to enhance magnetic field effects via the chirality-induced spin selectivity (CISS) effect, yet the mechanism underlying this enhancement remains unresolved. In this work, we systematically investigate the impact of CISS on the directional magnetic sensitivity of prototypical radical pair reactions, analyzing two distinct models--one generating spin polarization and, for the first time, one generating coherence. We find that CISS-induced spin polarization significantly enhances magnetic sensitivity by introducing triplet character into the initial state and reinforcing the quantum Zeno effect, paralleling enhancements observed in triplet-born radical pairs subject to strongly asymmetric recombination. In contrast, CISS-generated spin coherence does not provide a significant improvement in sensitivity. These findings indicate that CISS is not itself a universal enhancer of sensitivity or coherence in radical-pair reactions, and its influence must be evaluated case by case, particularly in relation to the quantum Zeno effect. Additionally, we provide a unified interpolation scheme for modeling CISS-influenced initial states and recombination dynamics, encompassing the principal models currently discussed in the literature for singlet and triplet precursors.