Testing General Relativity with Atom Interferometry

The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations. We propose such an experiment that will initially test the equivalence principle to 1 part in ${10}^{15}$ (300 times better than the current limit), and 1 part in ${10}^{17}$ in the future. It will also probe general relativistic effects—such as the nonlinear three-graviton coupling, the gravity of an atom’s kinetic energy, and the falling of light—to several decimals. In contrast with astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables.

Figure 1

A space-time diagram of a light-pulse atom interferometer. The black curves indicate the geodesic motion of a single atom near the surface of the Earth. Laser light used to manipulate the atom is incident from above (light gray) and below (dark gray) and travels along null geodesics. The finite speed of the light has been exaggerated.