Applied Physics Seminar

Interpreting quantum mechanics and extending it to describe gravitational fields still holds profound mysteries. We show that the theory – relativistic, with spin, in strong gravity – can be re-constructed as a picture of waves oscillating at the Compton frequency mc^2/h that are red-shifted and time-dilated just like conventional clocks (m is the particle mass). We find an exact form of the Dirac equation in curved space-time that is well-suited for finding analytical or numerical solutions.

The talk will focus on our experiments that were inspired by this picture: (i) tests of the equivalence principle at 10^-9 accuracy; (ii) a clock that measures time by the Compton frequency of cesium atoms and a planned gravitational Aharonov-Bohm experiment, showing that a massive particle is all that is needed to define a time-scale, on paper and in the lab; (iii) a realization of the unit of mass with state of the art precision. Moreover, (iv) our ongoing measurement of the fine structure constant. At 2x10^-9 accuracy, it has been the world's third best. We have since reduced the leading systematic error about 8-fold and the statistical error about 10-fold. As an outlook, we will discuss atom interferometry in space, with antimatter, and for gravitational wave detection.