Schiff Moment Search with Molecular Ions: 229ThF+

Why is the universe made of matter rather than antimatter?

The Standard Model of Particle Physics doesn’t provide an answer to this question. A crucial missing piece is an undiscovered Charge-Parity (CP) symmetry violation, much larger than in the Standard Model. The Nuclear Schiff Moment, along with the electron Electric Dipole Moment (EDM), offers strong potential for discovering new sources of CP violation. Nuclei with octupole deformation, in particular, display around 1000 times greater sensitivity compared to the electron EDM. Thorium-229 is one of the octupole-deformed nuclei with a long half-life and loading efficiency. We aim to explore CP-violating physics at the ~100 TeV scale using molecular ions, particularly 229ThF+. 

Additionally, we also study the properties of Th-227 and other thorium isotopes using collinear laser spectroscopy to establish the next generation BSM search using ions.

Why Trapped Ions? Why Molecules? Why 229ThF+?

Nuclei with octupole deformation are typically radioactive, very rare, and short-lived. 

• Th-229 is expected to have a large octupole deformation with a long half-life (8000 years).

• Th-229 is available from an even more stable U-233 through α-recoil. Loading of Th-229 ions has been established through the nuclear clock research.

• Molecules offer high effective electric fields, about 4-5 orders of magnitude higher than lab-scale fields

• Ion trap's high electrical trapping potential allows efficient capture of rare isotopes

• Long coherence time enables sensitive search even with a limited number, demonstrated in the JILA electron EDM experiment.

• The complication comes from Th-229's nuclear spin (I=5/2). We will develop efficient rotational cooling and hyperfine control methods. 

• By inventing a non-destructive quantum state preparation and readout method, we can further enhance the efficiency. Namely, trap once and reuse multiple times for measurement

• With a realistic number, we hope we can probe ~100TeV scale physics!

Beyond 229ThF+?

By definition, ions are trappable as long as it has a charge. We hope the method we develop could be applicable to any general rare molecular ions. 

Th-227 (τ_{1/2}=18 days) has a nuclear spin of I=1/2. 227ThF+, therefore, will have a much simpler structure. Efficient production of Th-227 ions will enhance the sensitivity further.

Development of the ion trap techniques will allow a search for CP-violation using many different elements, covering a wide range of parameter space.