Towards quantum simulation with ultracold polar molecules

超冷和量子简并原子气体已经被用来研究大量新的和有趣的物理现象，从超流的基础研究到强关联的多体系统。随着该领域的成熟，人们对制造类似的分子气体的兴趣越来越大，丰富的内部结构提供了进入新的、令人着迷的物理的途径。获得这些财富的最有希望的途径之一是，在将成对的原子结合成双原子分子之前，利用这种能力将原子气体冷却到简并。在这种背景下，异核分子的形成特别令人感兴趣，因为在基态下，分子表现出永久的电偶极矩，引起长程各向异性相互作用。这种相互作用极大地改变了气体在超低温下的行为，并发现了许多应用。一个这样的应用是在量子模拟领域，其中限制在三维光学晶格上的相互作用分子的规则阵列被用来模拟通常与凝聚态物理有关的问题。这个项目的目标是探索使用超冷分子-红细胞或CsYb-的量子模拟协议的实验实现。在RBC的情况下，我们的研究将调查使用分子的旋转态来编码伪自旋来模拟量子磁性，而在CsYb实验中可以利用未配对电子的自旋。新的工作将集中在一维、二维和三维光学晶格的发展上。最终，我们将开发在单晶格位置水平上探测分子的方法，以便深入了解晶格中复杂的多体动力学。

Ultracold and quantum degenerate atomic gases have been exploited to study a vast array of novel and interesting physical phenomena ranging from fundamental studies of superfluidity to strongly-correlated many body systems. As the field has matured there has been a growing interest in the quest to produce similar gases of molecules, where the rich internal structure offers access to new, fascinating physics. One of the most promising routes to these riches is to exploit the ability to cool atomic gases to degeneracy before associating pairs of atoms to form diatomic molecules. In this context the formation of heteronuclear molecules is of particular interest as, in the ground state, the molecules exhibit a permanent electric dipole moment that gives rise to long-range anisotropic interactions. Such interactions dramatically modify the behaviour of the gas at ultracold temperatures and find many applications. One such application is in the area of quantum simulation where a regular array of interacting molecules confined on a three dimensional optical lattice is used to simulate problems more usually associated with condensed matter physics. The goal of this project is to explore experimental implementations of quantum simulation protocols using ultracold molecules - either RbCs or CsYb. In the case of RbCs, our studies will investigate the use of rotational states of the molecule to encode a pseudo spin for simulation of quantum magnetism, whereas in CsYb experiments can exploit the spin of the unpaired electron. New work will focus on the development of optical lattices in 1D, 2D and 3D. Ultimately we will develop methods to probe the molecules at the level of single lattice sites in order to gain insight into the complex many-body dynamics in the lattice.