The Avian Compass can be Sensitive even without Sustained Quantum Coherence

TL;DR

This study shows that the avian magnetic compass can be sensitive to Earth's magnetic field even without sustained quantum coherence, emphasizing the role of hyperfine anisotropy over coherence longevity.

Contribution

It demonstrates that sustained quantum coherence is not necessary for avian compass sensitivity, highlighting hyperfine anisotropy as a key factor.

Findings

Long-lived coherence is unlikely in realistic hyperfine environments.

Hyperfine anisotropy is essential for compass sensitivity.

Sensitivity can occur without sustained quantum coherence.

Abstract

Theoretical studies indicating the presence of long-lived coherence in the radical pair system have engendered questions about the utilitarian role of sustained coherence in the avian compass. In this manuscript, we investigate this for a realistic multi-nuclear radical pair system, along with the related question of its sensitivity to the geomagnetic field. Firstly, we find that sustenance of long-lived coherence is unlikely in a realistic hyperfine environment. Secondly, probing the role of the hyperfine interactions on the compass sensitivity, we establish the hyperfine anisotropy as an essential parameter for the sensitivity. Thereby, we are able to identify a parameter regime where the compass would exhibit sensitivity even without sustained coherence.