Before revision:  In this study, we analyze the radical pair model form a microscopic spin transitional point of view and establish the role of nuclear and environmental decoherence in radical pair spin dynamics. We identify the spin interplay between singlet state and three triplet states of radical due to Zeeman and hyperfine and examine the distinctive roles of nuclear and environmental decoherence from this perspective.
After revision:  In this study, we analyze the radical pair model form a microscopic spin transitional point of view . This helps to elucidate the interplay between the hyperfine and Zeeman interactions that enables the avian compass, and the distinctive effects of nuclear and environmental decoherence from this perspective.