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

【摘要】 We report a compact experimental setup for producing a quantum degenerate mixture of Bose²³Na and Fermi⁴⁰K 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 D₂ line for²³Na and D₁ line for⁴⁰K. The microwave evaporation cooling is used to cool²³Na in |F = 2, m_F= 2〉 in an optically plugged magnetic trap, meanwhile,⁴⁰K in |F = 9/2, m_F= 9/2〉 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where²³Na atoms are immediately transferred to |1, 1〉 for further effective cooling to avoid the strong three-body loss between²³Na atoms in |2, 2〉 and⁴⁰K atoms in |9/2, 9/2〉. At the end of the evaporation in optical trap, a degenerate Fermi gas of⁴⁰K with 1.9 × 10⁵ atoms at T/T_F = 0.5 in the |9/2, 9/2〉 hyperfine state coexists with a Bose–Einstein condensate（BEC） of²³Na with 8 × 10⁴ atoms in the |1, 1〉 hyperfine state at 300 n K. We also can produce the two species mixture with the tunable population imbalance by adjusting the²³Na magneto–optical trap loading time.更多还原

【Abstract】 We report a compact experimental setup for producing a quantum degenerate mixture of Bose²³Na and Fermi⁴⁰K 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 D₂ line for²³Na and D₁ line for⁴⁰K. The microwave evaporation cooling is used to cool²³Na in |F = 2, m_F= 2〉 in an optically plugged magnetic trap, meanwhile,⁴⁰K in |F = 9/2, m_F= 9/2〉 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where²³Na atoms are immediately transferred to |1, 1〉 for further effective cooling to avoid the strong three-body loss between²³Na atoms in |2, 2〉 and⁴⁰K atoms in |9/2, 9/2〉. At the end of the evaporation in optical trap, a degenerate Fermi gas of⁴⁰K with 1.9 × 10⁵ atoms at T/T_F = 0.5 in the |9/2, 9/2〉 hyperfine state coexists with a Bose–Einstein condensate（BEC） of²³Na with 8 × 10⁴ atoms in the |1, 1〉 hyperfine state at 300 n K. We also can produce the two species mixture with the tunable population imbalance by adjusting the²³Na magneto–optical trap loading time.更多还原