Laser cooling to quantum degeneracy

Understand

We report on Bose-Einstein condensation (BEC) in a gas of strontium atoms, using laser cooling as the only cooling mechanism.

• The condensate is formed within a sample that is continuously Doppler cooled to below 1\muK on a narrow-linewidth transition.
• The critical phase-space density for BEC is reached in a central region of the sample, in which atoms are rendered transparent for laser cooling photons.
• The density in this region is enhanced by an additional dipole trap potential.