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).