Donley E A, Claussen N R, Cornish S L, Roberts J L, Cornell E A, Wieman C E
JILA, Campus Box 440, and Department of Physics, Campus Box 390, University of Colorado, Boulder, Colorado 80309, USA.
Nature. 2001 Jul 19;412(6844):295-9. doi: 10.1038/35085500.
When atoms in a gas are cooled to extremely low temperatures, they will-under the appropriate conditions-condense into a single quantum-mechanical state known as a Bose-Einstein condensate. In such systems, quantum-mechanical behaviour is evident on a macroscopic scale. Here we explore the dynamics of how a Bose-Einstein condensate collapses and subsequently explodes when the balance of forces governing its size and shape is suddenly altered. A condensate's equilibrium size and shape is strongly affected by the interatomic interactions. Our ability to induce a collapse by switching the interactions from repulsive to attractive by tuning an externally applied magnetic field yields detailed information on the violent collapse process. We observe anisotropic atom bursts that explode from the condensate, atoms leaving the condensate in undetected forms, spikes appearing in the condensate wavefunction and oscillating remnant condensates that survive the collapse. All these processes have curious dependences on time, on the strength of the interaction and on the number of condensate atoms. Although the system would seem to be simple and well characterized, our measurements reveal many phenomena that challenge theoretical models.
当气体中的原子被冷却到极低温度时，在适当条件下，它们会凝聚成一种被称为玻色 - 爱因斯坦凝聚态的单一量子力学状态。在这样的系统中，量子力学行为在宏观尺度上是明显的。在这里，我们探讨当控制玻色 - 爱因斯坦凝聚态大小和形状的力的平衡突然改变时，它如何坍缩并随后爆炸的动力学过程。凝聚态的平衡大小和形状受到原子间相互作用的强烈影响。我们通过调节外部施加的磁场，将相互作用从排斥变为吸引来引发坍缩，从而获得了关于剧烈坍缩过程的详细信息。我们观察到从凝聚态中爆发的各向异性原子簇、以未被检测到的形式离开凝聚态的原子、凝聚态波函数中出现的尖峰以及在坍缩中幸存下来的振荡残余凝聚态。所有这些过程都对时间、相互作用强度和凝聚态原子数量有着奇特的依赖性。尽管该系统看似简单且特征明确，但我们的测量揭示了许多挑战理论模型的现象。
