Light propagation and atom interferometry in gravity and dilaton fields

Abstract: Dark matter or violations of the Einstein equivalence principle influence the motion of atoms, their internal states as well as electromagnetic fields, thus causing a signature in the signal of atomic detectors. To model such new physics, we introduce dilaton fields and study the modified propagation of light used to manipulate atoms in light-pulse atom interferometers. Their interference signal is dominated by the matter's coupling to gravity and the dilaton. Even though the electromagnetic field contributes to the phase, no additional dilaton-dependent effect can be observed. However, the light's propagation in gravity enters via a modified momentum transfer and its finite speed. For illustration, we discuss effects from light propagation and the dilaton on different atom-interferometric setups, including gradiometers, equivalence principle tests, and dark matter detection.