We trap and cool erbium atoms in a quadrupole magnetic field using a stabilized laser tuned to the blue side of a narrow (8 kHz) atomic resonance. Cooling and trapping are observed with a single incident beam, as well as with multiple beams. The trap forms at a position of non-zero magnetic field with the trap population polarized in a weak-field seeking spin state, while Doppler cooling on the narrow transition leads to trap temperatures as low as a few microkelvin. A one-dimensional, semiclassical model elucidates the unique interplay between magnetic and optical forces in our trap. These results constitute an alternative technique for laser cooling on weak transitions, with applications to the other rare-earth elements as well as magnetically trapped, metastable alkaline earth atoms.
Citation: Physical Review Letters
Pub Type: Journals