Cooling all external degrees of freedom of optically trapped chromium atoms using gray molasses
We report on a scheme to cool and compress trapped clouds of highly magnetic 52Cr atoms. This scheme combines sequences of gray molasses, which freeze the velocity distribution, and free evolutions in the (close to) harmonic trap, which periodically exchange the spatial and velocity degrees of freedom.
arXiv:1812.09177 (2018) / Phys. Rev. A 99, 023607 (2019)
Taken together, the successive gray molasses pulses cool all external degrees of freedom, which leads to an increase of the phase-space density (PSD) by a factor of ≈250, allowing to reach a high final PSD of ≈1.7×10−3. These experiments are performed within an optical dipole trap, in which gray molasses works as well as it does in free space.
The obtained samples are then an ideal starting point for the evaporation stage aiming at the quantum regime.
