Progress in an experiment to measure the electric dipole moment of the electron using YbF molecules

We report progress on an ongoing experiment to measure the electron EDM using YbF molecules [1].

We have increased the initial population of YbF molecules in the ground state by a factor of six through a combination of repump lasers, microwaves and rf fields. We have also improved our detection efficiency by a factor of 40. This is due to better collection optics, and a better detection scheme which can scatter many more photons per molecule. The new detection scheme also allows us to measure both quadratures of the interferometer.

Spurious magnetic fields are a major source of random and systematic error in our experiment, and therefore we have improved our control and measurement of magnetic fields. This was done by re-designing the electric field plates for lower magnetic Johnson noise, and by installing several low-noise magnetometers inside the machine.

Together, we will be able to measure the electron EDM at the 10^(-29) e cm level, which is competitive with the current limit of 1.1 * 10^(-29) e cm set by the ACME collaboration [2].


[1] J J Hudson et. al., Nature Vol. 473, 493 (2011).
[2] ACME Collabration, Nature Vol. 562, 355 (2018).