Quantum coherence and sensitivity of avian magnetoreception

TL;DR

This paper investigates the quantum mechanisms behind avian magnetoreception, showing that radical pair coherence times are around a microsecond and that environmental noise can enhance navigation sensitivity.

Contribution

It provides experimental-based estimates of radical pair lifetime and demonstrates that environmental noise can improve the sensitivity of the avian magnetic compass.

Findings

Radical pair lifetime is approximately one microsecond.

Environmental noise can enhance magnetic sensitivity.

Long coherence times are not necessary for effective navigation.

Abstract

Migratory birds and other species have the ability to navigate by sensing the geomagnetic field. Recent experiments indicate that the essential process in the navigation takes place in bird's eye and uses chemical reaction involving molecular ions with unpaired electron spins (radical pair). Sensing is achieved via geomagnetic-dependent dynamics of the spins of the unpaired electrons. Here we utilize the results of two behavioral experiments conducted on European Robins to argue that the average life-time of the radical pair is of the order of a microsecond and therefore agrees with experimental estimations of this parameter for cryptochrome --- a pigment believed to form the radical pairs. We also found a reasonable parameter regime where sensitivity of the avian compass is enhanced by environmental noise, showing that long coherence time is not required for navigation and may even spoil it.