The frontier of low-temperature physics has advanced to the mid pico-Kelvin (pK) regime but progress has come to a halt because of the problem of gravity. Ultra cold atoms must be confined in some type of potential energy well: if the depth of the well is less than the energy an atom gains by falling through it, the atom escapes. This article reviews ultra cold atom research, emphasizing the advances that carried the low temperature frontier to 450 pico-Kelvin. We review micro gravity methods for overcoming the gravitation limit to achieve further low temperature using free fall techniques such as a drop tower, sounding rocket, parabolic flight plane and the Space Station. We describe two techniques that give promise of further advance-an atom chip and an all-optical trap-and present recent experimental results. Basic¬¬¬ research in new regimes of observation has generally led to scientific discoveries and new technologies that benefit society. We expect this to be the case as the low temperature frontier advances and we propose some new opportunities for research.

中文翻译：

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皮开尔文物理学的出现

低温物理学的前沿已经发展到中皮开尔文 (pK) 范围，但由于重力问题，进展已经停止。超冷原子必须被限制在某种势能井中：如果势能井的深度小于原子穿过它而获得的能量，原子就会逃逸。本文回顾了超冷原子研究，强调了将低温前沿带到 450 皮开尔文的进展。我们回顾了使用自由落体技术（例如落塔、探空火箭、抛物线飞行飞机和空间站）克服重力限制以实现进一步低温的微重力方法。我们描述了两种有望进一步发展的技术——原子芯片和全光阱，并展示了最近的实验结果。新观察体制的基础研究通常会带来有益于社会的科学发现和新技术。随着低温前沿的发展，我们预计情况会如此，我们提出了一些新的研究机会。