Physical Mechanism Of Bird Navigation

With the rapid development of quantum mechanics, it has been used in various fields,such as quantum information, quantum thermodynamics, quantum optics and so on. Recently, combining quantum mechanics and biology, a new discipline named quantum biology emerges. The purpose of the quantum biology is to reveal the nature of biological phenomena more fundamentally by using quantum theory. As a famous direct of quantum biology, the birds’ navigation has aroused much interest. In this paper, based on the radical pair model,we investigate the physical mechanism of the birds’ navigation in detail and present a detailed account of some important experimental results; investigate the roles of entanglement and quantum coherence played on the navigation; and we also investigate the effects of the environmental noise.In the chapter 1, we review the connection between quantum mechanics and birds’ navigation and analyze the development and significance of bird’ navigation. In the chapter 2, we mainly introduce some basic concepts, such as the angular momentum theory including electronic spin and nuclear spin; the hyperfine interaction including Fermi contact potential and anisotropic hyperfine coupling. Based on these basic concepts, we also introduce the radical pair model in detail. In the chapter 3, we review the radical pair mechanism and present a detailed account of the following issues: How the hyperfine coupling between the electronic spin and nuclear spin induces the singlet-triplet state transition; why the vertical radio frequency field can disorient the birds, while the parallel can not; and why the birds are able to train to different field strengths. In the chapter 4, we investigate who among entanglement,quantum coherence or any one else, completely determines the magnetic sensitivity. We find that the magnetic sensitivity is completely determined by the dark state population, and the dark state coherence and quantum entanglement have no direct contribution to it. In the chapter 5, we investigate the effects of the hyperfine coupling noise and the magnetic noise, and find that the magnetic sensitivity is very fragile to the vertical magnetic noise, but is robust to and even is enhanced by the parallel magnetic noise. As for the hyperfine noise, the magnetic sensitivity is more robust to it. At last, we summarize this paper and point out the direction for future researches in chapter 6.