Magneto-optical trapping of the fermionic titanium isotopes ^47Ti and ^49Ti

Demonstrate magneto-optical trapping of the fermionic titanium isotopes ^47Ti and ^49Ti on the 498 nm a^5F5 → y^5G^o_6 cooling transition by developing and incorporating additional repumping light that addresses the hyperfine structure on both the 498 nm cooling transition and the 391 nm optical-pumping transition, so as to maintain population in the stretched (maximum total spin) laser-cooling state.

Background

The paper reports the first realization of laser cooling and trapping of titanium using a magneto-optical trap (MOT) operating on the 498 nm transition from the metastable a^5F5 state to the y^5G^o_6 state. MOTs are demonstrated for the three bosonic isotopes ^46Ti, ^48Ti, and ^50Ti, which have zero nuclear spin and thus lack hyperfine structure.

In contrast, the two fermionic isotopes ^47Ti and ^49Ti possess nuclear spin and exhibit hyperfine structure on both the optical-pumping and laser-cooling transitions. The authors state that they were unable to observe MOTs for these fermionic isotopes and indicate that additional repumping light will be required to maintain population in the stretched laser-cooling state. This establishes a concrete unresolved task: to design and implement an effective repumping scheme that enables MOT operation for ^47Ti and ^49Ti.