Single-Stage Sub-Doppler Cooling of Alkaline Earth Atoms
X Xu, T Loftus, J W. Dunn, C H. Greene, John L. Hall, Alan Gallagher, Jun Ye
We report the first experimental study of sub-Doppler cooling in alkaline earth atoms (87Sr) enabled by the presence of nuclear spin-oriented magnetic gedeneracy in the atomic ground state. Sub-Doppler cooling in a ς+-ς- configuration is achieved despite the presence of multiple, closely spaced excited states. This surprising result is confirmed by an expanded mulit-level theory of the radiative cooling force. Detailed investigations of the cooling dynamics with respect to various experimental parameters such as cooling beam intensity, frequency detuning, and atomic number and density have revealed new insights to the heating mechanism in alkaline earth atoms. Our findings represent an important step twoards a complete understanding of the (ς+-ς-) cooling force and will play an important role in the future development of neutral atom based optical frequency standards.
Physical Review Letters
alkaline earth atoms, magneto-optical trap, optical frequency standards, sub-Doppler cooling
, Loftus, T.
, Dunn, J.
, Greene, C.
, Hall, J.
, Gallagher, A.
and Ye, J.
Single-Stage Sub-Doppler Cooling of Alkaline Earth Atoms, Physical Review Letters
(Accessed February 27, 2024)