Degenerate Raman sideband cooling of 40K atoms

We report on the implementation of degenerate Raman sideband cooling of 40K atoms. The scheme incorpo-rates a three-dimensional (3D) optical lattice, which confines the atoms and drives the Raman transitions. The optical cooling cycle is closed by two optical pumping beams. The wavelength of the laser beams forming the lattice is close to the D2 atomic transition, while the optical pumping is operated near the D1 transition. With this cooling method, we achieve a temperature of similar to 1 mu K of a cloud with similar to 107 atoms. This corresponds to a phase space density of 10-3. Moreover, the fermionic ensemble is spin polarized to conditions which are favorable for subsequent evaporative cooling. We study the dependence of the cooling scheme on several parameters, including the applied magnetic field and the detuning, duration, and intensity profile of the optical pumping beams. Adding this optical cooling stage to current Fermi gas experiments can improve the final conditions and increase the data rate.

Automated summary

We report the implementation of degenerate Raman sideband cooling of 40K atoms. The scheme incorporates a three-dimensional optical lattice and optical pumping beams for closing the cooling cycle. With this method, we achieve a temperature of about 1 μK and a phase space density of 10-3 for a cloud of 107 atoms. The spin-polarized fermionic ensemble is favorable for subsequent evaporative cooling.