Laser cooling in an optical lattice that employs Raman transitions (4 pages)

Rachel Sapiro, Rui Zhang, Natalya V. Morrow +2 more

R. Zhang, Natalya V. Morrow, P. R. Berman +1 more

We demonstrate laser cooling in an optical lattice that employs Raman transitions. Four laser beams with different frequencies form a one-dimensional lattice with a basic lattice period that is a factor of 2 less than in standard optical lattices. Rb atoms are cooled to $8\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$. We measure the intensity- and detuning-dependence of the cooling mechanism. Our experimental results agree well with theoretical models.

Johan Jersblad

David S. Weiss

R. Zhang, Rachel Sapiro, Natalya V. Morrow +1 more

Reduced-period optical lattices based on Raman transitions allow for sub-Doppler laser cooling. An important parameter of this Raman optical lattice is the frequency difference ${\ensuremath{\Delta}}_{\mathrm{d}}$ between two virtual energy levels involved in the atom-field interaction scheme. In this work, we use experimental time-of-flight data and quantum simulations to characterize laser cooling in the Raman lattice as a function of ${\ensuremath{\Delta}}_{\mathrm{d}}$. Two different domains of laser cooling are identified. For small ${\ensuremath{\Delta}}_{\mathrm{d}}$, atoms are cooled due to a well-known mechanism that also occurs in standard optical lattices. For large ${\ensuremath{\Delta}}_{\mathrm{d}}$, atoms are cooled based on Raman transitions. We study the transition between the two domains of laser cooling in detail.

Guohui Li, Xinye Xu

We propose a method for laser cooling two-valence-electron fermionic atoms. Our protocol employs resolved-sideband cooling on the stimulated Raman transition between the two magnetic sublevels (m = F and m = F − 1) of the ground state with total angular momentum F. The optical pumping from m = F − 1 to 1 P 1 are used to decouple atoms in the m = F − 1 state. We calculate the Raman coupling generated by an engineered optical lattice. The result shows that it is possible to laser cool the two-valence-electron fermionic atoms to the ground state. The atoms in the ground state provide a new system for quantum optics.