Dark states and coherent control of spin states in molecular magnets

We propose a scheme to realize the coherent control of spin states of the molecule magnet, Ni-4. We introduce transverse magnetic fields with special frequencies. When the frequencies of transverse magnetic fields match in some conditions, we obtain dark states in Ni-4 molecules. Through adjusting the magnitude of the magnetic fields, we can obtain any arbitrary superposition of the two ground spin states of Ni-4 molecules.