Ultracold YbF molecules for measuring the electron's electric dipole moment*

Theories that extend the Standard Model (SM) generally contain additional sources of CP-violation and predict the electron to have an electric dipole moment (eEDM) large enough to be measured by today's experiments. The eEDM may be measured by observing spin precession in YbF molecules in an electric field [1]. Recent results [1-4] already strongly constrain beyond-SM theories.

Laser cooling of molecules was first demonstrated in 2010 [5]. An ultracold beam of YbF could increase the eEDM measurement sensitivity by two orders of magnitude [6]. We have demonstrated 1D sub-Doppler transverse cooling of our YbF beam to below 100 μK [6] and recently extended the technique to 2D.

[1] J. J. Hudson et al., Nature 473, 493 (2011).
[2] J. Baron et al., Science 343, 269 (2014).
[3] W. B. Cairncross et al., Phys. Rev. Lett. 119, 153001 (2017).
[4] V. Andreev et al., Nature 562, 355 (2018).
[5] E. S. Shuman et al., Nature 467, 820 (2010).
[6] J. Lim et al., Phys. Rev. Lett. 120, 123201 (2018).