Narrow-line magneto-optical trap for europium

Abstract

We report on the realization of a magneto-optical trap (MOT) for europium atoms using a narrow-line cooling transition with a natural linewidth of 97 kHz. Our starting point is continuous capturing and cooling of optically pumped metastable europium atoms. We have employed simultaneous MOT for the metastable and ground-state atoms. The trapped metastable atoms are successively pumped back to the ground state and then continuously loaded to the narrow-line MOT, where up to $4.7\times 10^7$ atoms are captured. A spin-polarized sample at a temperature of $6\mu \mathrm{K}$ and with a peak number density of $2.2\times 10^{11}\mathrm{c}{\mathrm{m}}^{-3}$ is obtained through the compression process, resulting in a phase space density of $3\times 10^{-5}$.

5 pages, 4 figures, 2 tables