We use atom interferometry to sense the very small force that is predicted by theories of dark energy. Cosmologists have observed that the expansion of the universe is accelerating and propose that this is due to a new scalar field, whose particles are very light. The energy density of this field drives the universal acceleration, but it is also expected to produce a small force between atoms and a test mass in vacuum. Our experiment uses atom interferometry to search for that force[1,2].

[1] Clare Burrage, Edmund J. Copeland, E. A. Hinds. JCAP 03 (2015) 042.

[2] Hamilton et al. Science, 349, 849-851 (2015).