Two-stage laser cooling and optical trapping of thulium atoms

We propose to use the magnetic-dipole transition at λ = 1.14 μm coupling two ground state fine-structure components of thulium (Tm), as a 'clock transition' in optical clocks. We have demonstrated first stage laser cooling of Tm atoms down to a temperature of 25 μK using a strong transition at λ = 410.6 nm and we have also shown preliminary results for second stage cooling using a weaker transition at λ = 530.7 nm (natural linewidth γG = 350 kHz). Laser cooled atoms have been trapped in an optical dipole trap and in a 1D optical lattice operating near 532 nm.