Evidence for Efimov quantum states in an ultracold gas of caesium atoms
Evidence for Efimov quantum states in an ultracold gas of caesium atoms
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DOI：
10.1038/nature04626
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发表时间：
2006-03-16
期刊：
影响因子：
64.8
通讯作者：
Grimm, R
中科院分区：
文献类型：
--
作者：
Kraemer, T;Mark, M;Grimm, R
由三个相互作用的粒子组成的系统因其复杂的物理行为而臭名昭著。在少体量子物理学中，一个具有里程碑意义的理论结果是Efimov的预测（1,2），即三个具有共振两体相互作用的相同玻色子会出现一组普遍的束缚三聚体态。与直觉相反，这些状态甚至在没有相应的二体束缚态的情况下也存在。自从35年前在核物理背景下提出Efimov问题以来，它在许多物理领域引起了极大的兴趣（3-8）。然而，对Efimov量子态的观测仍然是一个难以实现的目标（3,5）。本文报道了在铯原子的超冷气体中观察到的叶菲莫夫共振。共振发生在大的负二体散射长度范围内，由三个自由原子耦合到一个叶菲莫夫三聚体引起。实验上，我们观察到当两体相互作用的强度发生变化时，其特征为巨大的三体重组损失（9,10）。我们还检测到正散射长度的复合损失最小值（9,11,12），表明衰减路径的破坏性干扰。我们的结果证实了Efimov物理学的中心理论预测，并代表了探索共振相互作用的少体系统的普遍特性的起点(7)。费什巴赫共振（13,14）提供了在两体水平上控制量子力学相互作用的关键，而叶菲莫夫共振将超冷物质（15）连接到少体量子现象的世界。
Systems of three interacting particles are notorious for their complex physical behaviour. A landmark theoretical result in few- body quantum physics is Efimov's prediction(1,2) of a universal set of bound trimer states appearing for three identical bosons with a resonant two- body interaction. Counterintuitively, these states even exist in the absence of a corresponding two- body bound state. Since the formulation of Efimov's problem in the context of nuclear physics 35 years ago, it has attracted great interest in many areas of physics(3-8). However, the observation of Efimov quantum states has remained an elusive goal(3,5). Here we report the observation of an Efimov resonance in an ultracold gas of caesium atoms. The resonance occurs in the range of large negative two- body scattering lengths, arising from the coupling of three free atoms to an Efimov trimer. Experimentally, we observe its signature as a giant three- body recombination loss(9,10) when the strength of the two- body interaction is varied. We also detect a minimum(9,11,12) in the recombination loss for positive scattering lengths, indicating destructive interference of decay pathways. Our results confirm central theoretical predictions of Efimov physics and represent a starting point with which to explore the universal properties of resonantly interacting few- body systems(7). While Feshbach resonances(13,14) have provided the key to control quantum- mechanical interactions on the two- body level, Efimov resonances connect ultracold matter(15) to the world of few- body quantum phenomena.