D. Sukachev

Magneto-optical trap for thulium atoms

Thulium atoms are trapped in a magneto-optical trap using a strong transition at 410 nm with a small branching ratio. We trap up to 7x10{sup 4} atoms at a temperature of 0.8(2) mK after deceleration in a 40-cm-long Zeeman slower. Optical leaks from the cooling cycle influence the lifetime of atoms in the magneto-optical trap which varies between 0.3 and 1.5 s in our experiments. The lower limit for the leaking rate from the upper cooling level is measured to be 22(6) s{sup -1}. The repumping laser transferring the atomic population out of the F=3 hyperfine ground-state sublevel gives a 30% increase for the lifetime and the number of atoms in the trap.

Zeeman slowing of thulium atoms

We demonstrate laser slowing of a hot thulium atomic beam using the nearly closed cycling transition 4f(13)6s(2)((2)F(o))(J=7/2)<-->4f(12)((3)H(5))5d(3/2)6s(2)(J=9/2) at 410.6 nm. Atoms are decelerated to velocities around 25 m/s by a 40 cm Zeeman slower. The flux of slowed atoms is evaluated as 10(7) s(-1)cm(-2). The experiment explicitly indicates the possibility of trapping Tm atoms in a magneto-optical trap.

Sub-doppler laser cooling of thulium atoms in a magneto-optical trap

Sub-Doppler laser cooling in a magneto-optical trap for thulium atoms at a wavelength of 410.6 nm has been experimentally studied. Without any dedicated molasses period of sub-Doppler cooling, the cloud of 3 × 106 atoms at a temperature of 25(5) μK was observed. The measured temperature is significantly lower than the Doppler limit of 240 μK for the cooling transition at 410.6 nm. The high efficiency of the sub-Doppler cooling process is due to a near-degeneracy of the Landé g-factors of the lower 4f136s2 (J = 7/2) and the upper 4f125d3/26s2 (J = 9/2) cooling levels.

Measurement of the 5D level polarizabilities in laser cooled Rb atoms

We report on accurate measurements of the scalar αS and tensor αT polarizabilities of the 5D fine structure levels 5D3/2 and 5D5/2 in Rb.

Laser cooling of thulium atoms

We demonstrated laser cooling and trapping of thulium atoms at sub-Doppler temperatures in a magneto-optical trap (MOT). Up to 3 × 106 thulium atoms were trapped in the MOT at temperatures down to 25(5) μK which is approximately 10 times lower than the Doppler limit. The lifetime of atoms in the MOT varied between 0.3–1.5 s and was restricted mostly by optical leaks from the upper cooling level. The lower limit for the leaking rate was estimated to be 22(6) s−1. Due to a big magnetic moment of Tm atoms, a part of them were trapped in a magnetic trap from the quadrupole field of the MOT. We observed about 3 × 104 purely magnetically trapped atoms at temperature of 25 μK with a lifetime in the trap of 0.5 s. Also we set up a “dark” MOT consisting of six crossed hollow beams which increased the number of trapped atoms by a factor of 5 leading to 1.5 × 107 atoms at the expense of higher temperature.

Laser cooling and trapping of thulium atoms for further investigation of collisional properties

We demonstrated deep laser cooling of thulium atoms on a weak closed transition in magneto-optical trap and reloading of an atomic ensemble into an optical lattice. 105 atoms with a temperature 10 μK were trapped.