In recent work with Maulik Parikh and Frank Wilczek we study the effect of a quantized gravitational wave on a LIGO-type gravitational wave detector. We find that the arm-length is subject to a stochastic tidal force whose properties depend on the exact quantum state of the gravitational wave, if gravitational waves are quantized. The quantum nature of gravitational waves may be detectable as an additional noise source in gravitational wave detectors.