Searching for dark energy with matter wave interferometry

The nature of dark energy, which makes up 70{\%} of the mass-energy of the universe, remains completely unknown. Chameleons are a simple scalar model for dark energy that mediate a force which is screened by bulk matter. However we can now probe these scalar fields using atoms as nearly ideal test masses in the vacuum of our cavity-based matter wave interferometer [1, 2]. Our first measurements ruled out a range of chameleons that would reproduce the observed cosmic acceleration [3]. Since then we have improved sensitivity by a factor of 100. With a similar future improvement, we will be sensitive to any possible chameleon field and other exotic models for dark energy and dark matter, such as symmetrons or f(R) gravity.\\[4 pt] \\[4 pt] [1] C. Burrage, E. Copeland, E Hinds, JCAP 03 (2015) 042 \\[4 pt] [2] P. Hamilton, M. Jaffe, J.M. Brown, L. Maisenbacher, B. Estey, H. M\"{u}ller, Phys. Rev. Lett. \textbf{114}, 100405 (2015) \\[4 pt] [3] P. Hamilton, M. Jaffe, P. Haslinger, Q. Simmons, H. M\"{u}ller, J. Khoury, Science \textbf{349}, 6250 (2015)