Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore.
Phys Rev Lett. 2012 Sep 14;109(11):110502. doi: 10.1103/PhysRevLett.109.110502.
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 the 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 lifetime 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 find a reasonable parameter regime where the 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.
候鸟和其他物种具有通过感应地磁场来导航的能力。最近的实验表明，导航过程中的关键步骤发生在鸟类的眼睛中，利用涉及具有不成对电子自旋的分子离子的化学反应（自由基对）。通过未配对电子自旋的地磁依赖动力学来实现感应。在这里，我们利用在欧洲知更鸟上进行的两项行为实验的结果来证明，自由基对的平均寿命约为微秒，因此与认为形成自由基对的色素隐花色素的该参数的实验估计值相符。我们还找到了一个合理的参数范围，其中环境噪声增强了鸟类罗盘的灵敏度，表明长相干时间不是导航所必需的，甚至可能会破坏它。
