Quantum kinetic theory. VI. The growth of a Bose-Einstein condensate
Quantum kinetic theory. VI. The growth of a Bose-Einstein condensate
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量子动力学理论。
DOI：
10.1103/physreva.62.033606
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发表时间：
1999
影响因子：
2.9
通讯作者：
C. Gardiner
中科院分区：
文献类型：
--
作者：
M. D. Lee;C. Gardiner
本文根据量子动力学理论对玻色-爱因斯坦凝聚体的生长过程进行了详细的分析，其中考虑了低陷阱能级占据的演化，高陷阱能级占据的完整玻色-爱因斯坦公式，以及加德纳等人提出的玻色诱导原子向凝聚态的直接转移。但在较低温度下，实验观察到的生长速率稍微更快。我们还证实了卡根等人提出的进化的“动力学”区域的图景，直到冷凝物开始的时间。引发后的行为基本上遵循我们原来的生长方程，但速率系数大大增加。
我们的增长模型隐含地给出了一个模型的冷凝物蒸汽系统的空间形状的冷凝物的增长，从而提供了一种替代目前的唯象拟合过程，基于零化学势蒸汽和一个E-Fermi形冷凝物的总和。我们的方法可能会得到显着不同的结果冷凝物的数量和温度从phenomentological拟合，并表示需要更系统的调查的增长动力学的冷凝物从过饱和蒸汽。
A detailed analysis of the growth of a BEC is given, based on quantum kinetic theory, in which we take account of the evolution of the occupations of lower trap levels, and of the full Bose-Einstein formula for the occupations of higher trap levels, as well as the Bose stimulated direct transfer of atoms to the condensate level introduced by Gardiner et al. We find good agreement with experiment at higher temperatures, but at lower temperatures the experimentally observed growth rate is somewhat more rapid. We also confirm the picture of the ``kinetic'' region of evolution, introduced by Kagan et al., for the time up to the initiation of the condensate. The behavior after initiation essentially follows our original growth equation, but with a substantially increased rate coefficient.
Our modelling of growth implicitly gives a model of the spatial shape of the condensate vapor system as the condensate grows, and thus provides an alternative to the present phenomenological fitting procedure, based on the sum of a zero-chemical potential vapor and a Thomas-Fermi shaped condensate. Our method may give substantially different results for condensate numbers and temperatures obtained from phenomentological fits, and indicates the need for more systematic investigation of the growth dynamics of the condensate from a supersaturated vapor.