Testing general relativity and alternative theories of gravity with space-based atomic clocks and atom interferometers
The successful miniaturisation of extremely accurate atomic clocks and atom interferometers invites prospects for satellite missions to perform precision experiments. We discuss the e ects predicted by general relativity and alternative theories of gravity that can be detected by a clock, which orbits the Earth. Our experiment relies on the pre- cise tracking of the spacecraft using its observed tick-rate. The spacecraft's reconstructed four-dimensional trajectory will reveal the nature of gravitational perturbations in Earth's gravitational field, potentially di erentiating between di erent theories of gravity. This mission can measure multiple relativistic e ects all during the course of a single exper- iment, and constrain the Parametrized Post-Newtonian Parameters around the Earth. A satellite carrying a clock of fractional timing inaccuracy of f=f 10 16 in an elliptic orbit around the Earth would constrain the PPN parametersj 1j;j 1j . 10 6 . We also briefly review potential constraints by atom interferometers on scalar tensor theories and in particular on Chameleon and dilaton models.