  We discuss the quantum mechanical description of a gravitational wave
interacting with a cavity electromagnetic field. Quantum fluctuations of the
gravitational vacuum induce squeezing in the optical field. Moreover, this
squeezing experiences revivals, a purely quantum effect. Measuring these
gravitationally induced revivals, although out of reach from experiments, would
provide evidence on the quantum nature of gravity. We also discuss the quantum
mechanical treatment of the interaction between coherent and squeezed
gravitational wave states and a gravity wave detector. In the case of a
coherent gravitational wave, we reproduce the result from the classical theory
with a quantum mechanical calculation. The case of a squeezed gravity wave is
not calculable within the classical theory, and could provide evidence on the
quantum nature of gravity.
