Double-degenerate Bose-Fermi mixture of strontium

Understand

We report on the attainment of a spin-polarized Fermi sea of 87-Sr in thermal contact with a Bose-Einstein condensate (BEC) of 84-Sr.

• Interisotope collisions thermalize the fermions with the bosons during evaporative cooling.
• A degeneracy of T/T_F=0.30(5) is reached with 2x10^4 87-Sr atoms together with an almost pure 84-Sr BEC of 10^5 atoms.