Alkaline-earth atoms offer narrow linewidth clock transitions that have been limited to lattice, MOT, and beam geometries due to material properties. We present compact vapor cell solutions for realizing clocks with these atoms.
At present, the best optical lattice clocks are based on the spectroscopy of trapped alkaline-earth-like atoms such as ytterbium and strontium. The development of mobile or even space-borne clocks necessitates concepts for the compact laser-cooling and trapping of these atoms with reduced laser requirements. Here, we present two compact and robust achromatic mirror structures for single-beam magneto-optical trapping of alkaline-earth-like atoms using two widely separated optical cooling frequencies. We have compared the trapping and cooling performance of a monolithic aluminum structure that generates a conventional trap geometry to a quasi-planar platform based on a periodic mirror structure for different isotopes of Yb. Compared to prior work with strontium in non-conventional traps, where only bosons were trapped on a narrow line transition, we demonstrate two-stage cooling and trapping of a fermionic alkaline-earth-like isotope in a single-beam quasi-planar structure.
We report a 100 kHz linewidth for the 1 S 0 to 3 P 1 intercombination line of 88 Sr atoms at 689 nm in a microfabricated (9×14×4.4) mm 3 vapor cell. This puts an upper bound on the residual gas pressure in the vapor cell of 10 mTorr. The microfabricated Sr vapor cell offers an inexpensive and scalable way to lock lasers in state-of-the-art cold-atom-based atomic clocks and quantum computing experiments. It also paves the way for compact and precise optical frequency references based on alkaline earth vapor cells.