Many-body physics of ultracold gas mixtures with large mass difference

这个项目是基于最近在我们小组发现的锂和铷原子混合物中的种间Feshbach共振。有了这些共振，就有可能创造出具有大质量比的玻色子和费米子原子的强关联多体量子系统。组分（费米6Li，玻色子7 Li和玻色子87 Rb）的大质量差异是我们实验的独特之处。它将使我们能够实现这样的场景，即费米锂在玻色子铷原子之间产生玻恩-奥本海默型相互作用势。这种相互作用的一个显著特征是最近已经预测的异质性Efimov态的存在。这些束缚态是由两个重原子（铷）通过交换一个轻原子（锂）之间的吸引力产生的。类似于最近观察到的同源物，这种新型异质三体量子化合物的能谱也有望遵守普适标度律。它们的实验验证是非常方便的混合物与大的质量比，在我们的实验中给出。铷原子之间锂诱导的玻恩-奥本海默力的第二个结果是形成“气态固体”，即在稀气体中的晶体结构，让人联想到固体中的金属结合。他们预计将出现在一个3D光学晶格预结构的混合物。在这个项目中，我们还计划解决基础多体物理学的进一步主题，如异质性Tonks气体和Luttinger液体与6Li-87 Rb费米子玻色子和7 Li-87 Rb玻色子玻色子混合物。有了我们改进的装置，这些系统应该很容易实现。我们的项目旨在对多体物理学中的基本模型进行严格的测试。总的来说，目前世界上许多团体所追求的这种模型的实验实现可能会成为超冷原子物理学最重要的长期结果。我们特殊的原子混合物从大质量差异的角度重新审视凝聚态和固态物理学中的基本问题，因此可能对解决这些问题做出重大贡献。

This project is based on interspecies Feshbach resonances in mixtures of lithium and rubidium atoms which have recently been discovered in our group. With these resonances it will be possible to create strongly correlated many body quantum systems of bosonic and fermionic atoms with large mass ratio. The large mass difference of the constituents (fermionic 6Li, bosonic 7Li, and bosonic 87Rb) is the unique feature of our experiment. It will allow us to realize scenarios in which fermionic lithium generates a Born-Oppenheimer type interaction potential between bosonic rubidium atoms. A prominent signature of such an interaction is the existence of heteronuclear Efimov states, which has been predicted recently. These bound states result from attractive forces between two heavy (rubidium) atoms via an exchange of one light (lithium) atom. Similar to its recently observed homonuclear counterpart, the energy spectrum of such a novel heteronuclear three-body quantum compound is also expected to obey universal scaling laws. Their experimental verification is strongly facilitated in mixtures with large mass ratios as given in our experiment. A second consequence of lithium-induced Born-Oppenheimer forces between rubidium atoms is the formation of “gaseous solids”, i.e. crystalline structures in a dilute gas reminiscent of metallic binding in a solid. They are expected to emerge from mixtures prestructured in a 3D optical lattice. Within this project we also plan to address further topics of fundamental many-body physics such as heteronuclear Tonks gases and Luttinger liquids with 6Li-87Rb fermion-boson and 7Li-87Rb boson-boson mixtures. With our improved apparatus these systems should be well accessible.Our project aims at stringent tests of fundamental models in many-body physics. In general, the experimental realization of such models currently pursued in many groups around the world may turn out as the most important long term result of ultracold atomic physics. Our particular atomic mixture readdresses fundamental questions in condensed matter and solid state physics from the angle of large mass differences and may thus significantly contribute to their solution.