  Gravitational waves, as predicted by Einstein's general relativity theory,
appear as ripples in the fabric of spacetime traveling at the speed of light.
We prove that the propagation of small amplitude gravitational waves in a
curved spacetime is equivalent to the propagation of a subspace of
electromagnetic states. We use this result to propose the use of entangled
photons to emulate the evolution of gravitational waves in curved spacetimes by
means of experimental electromagnetic setups featuring metamaterials.
