Atoms, Gravitation, and Lorentz Symmetry
Lorentz symmetry is fundamental to all of modern physics. High precision tests of local Lorentz invariance (LLI), and the Einstein equivalence principle (EEP), may also provide clues regarding how gravity and particle physics are united at high energy scales. I will describe my recent work in this area, including: use of existing tests of EEP to obtain comprehensive limits on EEP-violation for matter and (indirectly) antimatter at the part-per-million level; a design for a laboratory-scale demonstration of the gravitational Aharonov-Bohm effect for matter-waves; estimating the kinetic energies of nucleons in atomic nuclei to improve earlier limits on EEP-violation 100-fold; and a dysprosium spectroscopy test that improves limits on LLI-violation by a factor of ten, rivals astrophysical bounds drawn from the physics of 50 TeV electrons, and improves limits on electronic EEP-violation by more than a factor of 1,000.
Looking ahead, I will describe some new experiments that are in progress and on the drawing board, including one based on spectroscopy of rare earth ions in crystalline media. I will also describe a new proposal to use superradiant atomic ensembles as inertial references. This may ultimately enhance the sensitivity of terrestrial gravitational wave observatories at low frequencies, and expand the range of astrophysical phenomena they are sensitive to. AMO physics has historically provided some of the best tests of gravity and fundamental symmetries, and will continue to do so in the years ahead.