  We study an optomechanical system in which a microwave field and an optical
field are coupled to a common mechanical resonator. We explore methods that use
these mechanical resonators to store quantum mechanical states and to transduce
states between the electromagnetic resonators from the perspective of the
effect of mechanical decoherence. Besides being of fundamental interest, this
coherent quantum state transfer could have important practical implications in
the field of quantum information science, as it potentially allows one to
overcome intrinsic limitations of both microwave and optical platforms. We
discuss several state transfer protocols and study their transfer fidelity
using a fully quantum mechanical model that utilizes quantum state-diffusion
techniques. This work demonstrates that mechanical decoherence should not be an
insurmountable obstacle in realizing high fidelity storage and transduction.
