Searching for dark energy candidates using atom interferometry
We are working on light pulse atom interferometers as atom accelerometers for force sensing. We are exploring the limits of force sensing using matter-wave interferometry.
We start by loading a large number of atoms into a magneto-optical trap and cooling them via optical molasses. We start our accelerometer scheme by releasing these atoms from the trap and performing a state preparation scheme to deposit the atoms in one ground state. We then apply three carefully timed pulses to physically split, flip and finally recombine the atomic cloud's wavefunction via momentum transfer from the photons in a quantum mechanical analog to the Mach-Zehnder interferometer. We aim to construct a three-dimensional force sensing system with possible applications as a mass sensor with mass discrimination capabilities; further, we aim to make use of this technique as a dark energy detector to prove the capabilities of atom interferometers operating as atom accelerometers for use in searching for physics beyond the standard model of cosmology.
Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber , and therefore can detect the field with high sensitivity. New limits on the chameleon parameters from existing experiments show that most of the remaining chameleon parameter space is readily accessible using atom interferometry [1,2]. Having constructed an atom interferometer, we are currently performing a measurement campagin.
 Clare Burrage, Edmund J. Copeland, E. A. Hinds. JCAP 03 (2015) 042.
 Hamilton et al. Science, 349, 849-851 (2015).