Strong evaporative cooling towards Bose–Einstein condensation of a magnetically trapped caesium gas
Strong evaporative cooling towards Bose–Einstein condensation of a magnetically trapped caesium gas
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对磁捕获铯气体的玻色-爱因斯坦凝结进行强蒸发冷却
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
C J Foot
中科院分区：
文献类型：
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作者：
A. Thomas;S. Hopkins;S. L. Cornish;C J Foot
我们已经蒸发冷却铯原子在磁阱的温度低至8 nK，并产生了最终的相空间密度的四个因素内的玻色-爱因斯坦凝聚的发病所需的。在强制射频蒸发结束时，1500个处于F = 3，mF = −3状态的原子留在磁阱中。我们观察到一维蒸发冷却效率在非常低的温度下，作为捕获的样品进入碰撞厚（流体动力学）制度的减少。为了缓解这个问题，我们提出了一个修改后的捕获方案，三维蒸发是可能的。此外，我们还测量了铯原子两体非弹性碰撞率随磁场的变化。我们确认了先前在108.87（6），118.46（3）和133.52（3）G磁场下三个共振的位置，并降低了不确定性。
We have evaporatively cooled caesium atoms in a magnetic trap to temperatures as low as 8 nK and produced a final phase space density within a factor of four of that required for the onset of Bose–Einstein condensation. At the end of the forced radio-frequency evaporation, 1500 atoms in the F = 3, mF = −3 state remain in the magnetic trap. We observe a decrease in the one-dimensional evaporative cooling efficiency at very low temperatures as the trapped sample enters the collisionally thick (hydrodynamic) regime. To alleviate this problem we propose a modified trapping scheme where three-dimensional evaporation is possible. In addition, we report measurements of the two-body inelastic collision rates for caesium atoms as a function of magnetic field. We confirm the positions, with reduced uncertainties, of three previously identified resonances at magnetic fields of 108.87(6), 118.46(3) and 133.52(3) G.