Observations about utilitarian coherence in the avian compass.

Area of Science:

• Quantum Biology
• Bio-magnetism
• Avian Navigation

Background:

• The avian compass is hypothesized to involve radical pair spin dynamics.
• Quantum coherence may enhance compass sensitivity, but its role is speculative.
• Previous models lacked the complexity to fully investigate this phenomenon.

Purpose of the Study:

• To investigate the role of quantum coherence in avian magnetoreception.
• To explore realistic radical pair models inspired by cryptochrome.
• To correlate coherence measures with compass fidelity in complex systems.

Main Methods:

• Simulated realistic radical pair models with up to 21 nuclear spins.
• Varied relative radical orientations within the models.
• Assessed correlations between different coherence measures and compass fidelity.

Main Results:

• Electronic coherence did not predict compass sensitivity effectively.
• A robust correlation was found between compass sensitivity and a global coherence measure.
• Model complexity and the choice of coherence measure are crucial.

Conclusions:

• Global coherence, not just electronic coherence, is important for avian compass sensitivity.
• Realistic quantum models are essential for understanding biological magnetoreception.
• This work provides insights into the quantum mechanisms underlying avian navigation.