Quantum degenerate Bose-Fermi atomic gas mixture of 23Na and 40K

We report a compact experimental setup for producing a quantum degenerate mixture of Bose Na-23 and Fermi K-40 gases. The atoms are collected in dual dark magneto-optical traps (MOT) with species timesharing loading to reduce the light-induced loss, and then further cooled using the gray molasses technique on the D (2) line for Na-23 and D (1) line for K-40. The microwave evaporation cooling is used to cool Na-23 in | F = 2,m(F) = 2 in an optically plugged magnetic trap, meanwhile, K-40 in | F = 9/2,m(F) = 9/2 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where Na-23 atoms are immediately transferred to |1,1 for further effective cooling to avoid the strong three-body loss between Na-23 atoms in |2,2 and K-40 atoms in |9/2,9/2. At the end of the evaporation in optical trap, a degenerate Fermi gas of K-40 with 1.9 x 10(5) atoms at T/T-F = 0.5 in the |9/2,9/2 hyperfine state coexists with a Bose-Einstein condensate (BEC) of Na-23 with 8 x 10(4) atoms in the |1,1 hyperfine state at 300 nK. We also can produce the two species mixture with the tunable population imbalance by adjusting the Na-23 magneto-optical trap loading time.

Automated summary

We have developed a compact experimental setup to produce a quantum degenerate mixture of Bose Na-23 and Fermi K-40 gases. By using dual dark magneto-optical traps and the gray molasses technique, the atoms are efficiently collected and cooled. The resulting mixture consists of a degenerate Fermi gas of K-40 and a Bose-Einstein condensate of Na-23, with tunable population imbalance.