An Experiment to Measure the Electron's Electric Dipole Moment Using an Ultracold Beam of YbF Molecules

The fact that more matter than antimatter has been produced in the early stages of the universe is unexplained and known as the matter-antimatter-asymmetry problem [1]. One precondition is the combined violation of charge conjugation and parity (CP-violation) which is too small in the Standard Model. In almost all theories, CP-violation is also a precondition for the electron to have an electric dipole moment (de). A measurement of de can be a powerful test of theories beyond the Standard Model.

The value of de can be determined by measuring the precession rate of the electron spin in a strong electric field. Heavy polarized molecules with their high intra-molecular fields have already set a limit of |de| < 4.1×10−30 e cm [3]. To improve on this, we create a collimated, bright beam of laser cooled YbF molecules [4] and have built an experiment to measure de using this beam [2]. In this talk, I will present key aspects of this experiment which we hope can determine de with an uncertainty of 5×10−30 e cm in one day of measurement [4].

[1] Laurent Canetti et al New J. Phys. 14 095012 (2012).

[2] N J Fitch, J Lim, E A Hinds, B E Sauer, and M R Tarbutt. Methods for measuring the electron’s electric dipole moment using ultracold YbF molecules. Quantum Sci. Technol.,6, 014006, (2021).

[3] Roussy, et. al. "A new bound on the electron's electric dipole moment". arXiv:2212.11841 (2022).

[4] X. Alauze et al., An ultracold molecular beam for testing fundamental physics, Quantum Sci. Technol. 6, 044005 (2021).