  By utilizing quantum optics techniques, we examine the characteristics of a
quantum gravitational wave (GW) signature at interferometers. In particular, we
study the problem by analyzing the equations of motion of a GW interacting with
an idealized interferometer. Using this method, we reconstruct the classical GW
signal from a representation of the quantum version of an almost classical
monochromatic wave (a single-mode coherent state), then we discuss the
experimental signatures of some specific, more general quantum states. We
calculate the observables that could be used at future interferometers to probe
possible quantum states carried by the gravitational waves.
