超冷玻色气体中一维超辐射晶格的研究

Ultracold atoms in a periodic arrangement of microscopic trapping potentials form an intriguing physical system which is closely related to systems in condensed matter physics. The superimposed counter propagating laser beams interfere and the interference pattern results in a periodic potential landscape. Optical lattices have some distinctiveness, for example: the period and depth of lattice potentials, the dissipative component of the interaction can be artificially changed. The capability to load cold atoms in a periodic light structures traced the main route connecting the atomic and solid state physics frameworks. There is the relevant difference that an optical lattice can be reasonably considered as perfect even on a microscopic scale, since typical defects embedded in a material crystal (such as vacancies, dislocations or phonons) are absent. Therefore, it can be an ideal model..In this project, we will construct one dimensional superradiance lattice (SL). We will measure the superradiance emission spectra of a one-dimensional SL with 87Rb atoms in a Bose-Einstein condensate through the directional emission of one of the superradiant excited state in the lattice. The SL is constructed based on a standing wave-coupled electromagnetically induced transparency configuration. The SL provides a flexible and broad platform for many interesting and new physics waiting to be explored.

处于周期光晶格势中的原子是一个有趣的物理系统，它与凝聚态物理密切相关。利用激光的干涉原理可以为超冷原子提供了一个非常完整的周期势，而光晶格的独特之处在于势阱的周期和深度都可以人为改变，以及耗散作用可以通过改变光场的频率失谐来加以控制和利用。光晶格与固体之间有着强烈的相似性，并且由于光晶格不存在固体中破坏原子间长程相关的缺陷或杂质，因此，周期势场中的冷原子成为检验凝聚态物理中诸多效应的理想模型。.本项目中我们首先搭建一种新颖的晶格：一维超辐射晶格，然后将超冷玻色87Rb原子气体装载到超辐射晶格中，基于电磁诱导透明的原理，测量超辐射晶格中原子的超辐射跃迁散射谱，通过改变探测光的光强、方向、频率失谐来观察对超辐射晶格量子输运的影响。这将会为我们研究新的量子物质开辟了一个灵活的、广阔的平台。

目前，超冷原子已成为研究新型凝聚态物理的实验平台。基于87Rb的玻色爱因斯坦凝聚，我们实现了一维锯齿超辐射晶格，利用远失谐的驻波场模拟了一个人造磁场，其中两个驻波场之前的空间相对相位会在晶格锯齿环跃迁中引入磁通，由此研究了手性边界电流，该工作为冷原子中人造规范场的合成与检测提供了一种原位测量技术；基于光晶格中超冷原子的Kapitza–Dirac散射，研究了标量、矢量极化率与tune-out波长的关系；发展了利用两对拉曼光之间的相对相位精确调控拉曼耦合强度的新方法，实现了两个量子态相干跃迁的操控，该方法为超冷原子量子模拟实验提供了一个独特的操控参量：激光相位，由此拓展了受激拉曼跃迁的应用范围，为研究光与原子相互作用提供了一种新的方法。