Efficient production of a narrow-line erbium MOT with two-stage slowing

We describe an experimental setup for producing a large cold erbium (Er) sample in a narrow-line magneto-optical trap (MOT) in a simple and efficient way. We implement a pair of angled slowing beams with respect to the Zeeman slower axis, and further slow down atoms exiting from the Zeeman slower. The second-stage slowing beams effectively increase the capture velocity of the narrow-line MOT. This scheme is particularly useful when the Zeeman slower is operated at low power without the transverse cooling in the system, wherein we significantly improve the loading efficiency into the MOT and are able to trap more than $10^8$ atoms in the narrow-line MOT of $^{166}$Er atoms. This work highlights our implementation that greatly simplifies laser cooling and trapping of Er atoms and also benefits other similar elements.