SU(3)自旋轨道耦合的超冷玻色气体

After dissecting the current research progress of spin-orbit coupling in cold atom physics, we indicate that almost all the relevant research are based on the characteristic that the SO coupling makes the internal states coupled to their momenta via the SU(2) Pauli matrices. As the development of spin-orbit coupling towards to large spin systems, a complete description of the coupling among the internal states require introducing the SU(3) spin matrices. The SU(3) spin system has different algebraic structure, geometry and topology from the familiar spin case, thus will bring new physical model never happened in traditional condensed matter or any other matter, and open up a new door for discovering new states of matter and exotic quantum phenomena. In this project, we plan to design feasible experimental schemes to realizing SU(3) spin-orbit coupling, propose the corresponding theoretical models, and establish the numerical simulation platform of SU(3) spin-orbit coupled Bose gases. By the research, we expect to obtain the ground-state phase diagrams of Bose gases with SU(3) spin-orbit coupling, reveal the essential difference on the quantum many-body dynamics and collective excitation properties, and predict exotic topological excitations and new kinds of supersolid phases.

本项目在深入剖析冷原子自旋轨道耦合研究现状基础上指出现有研究大都集中在由泡利矩阵描述的SU(2)自旋系统，而随着自旋轨道耦合研究向大自旋方向发展，对于包含三个以上自旋态的系统，完备地描述各态之间的耦合需要引入具有更高对称性的SU(3)自旋矩阵。SU(3)自旋系统相较于SU(2)自旋系统具有完全不同的代数结构、几何和拓扑，因此SU(3)自旋轨道耦合可以提供通常凝聚态系统或其它系统无法实现的物理模型，从而为发现新物态和奇异量子现象开辟新的道路。本项目将以现有自旋轨道耦合相关研究为基础，提出实验可行的SU(3)自旋轨道耦合理论模型，建立并完善适用于SU(3)自旋轨道耦合超冷玻色气体的数值模拟平台。获得SU(3)自旋轨道耦合超冷玻色气体的基态相图；揭示SU(3)跟SU(2)自旋轨道耦合系统在量子多体动力学和集体激发性质等方面的本质区别；预言SU(3)自旋轨道耦合导致的奇异拓扑元激发和新的超固相。

超冷原子已经成为一个理想的平台来模拟和实现具有各种规范场的量子系统。其中最引人关注的一个课题是超冷原子气体中的自旋轨道耦合。目前，几乎所有的工作聚焦于SU(2)自旋系统，该系统的自旋是由泡利矩阵也就是SU(2)群的生成元描述的。三分量系统允许设计更加复杂的自旋轨道耦合形式，其自旋要求由盖尔曼矩阵也就是SU(3)群的生成元来描述。本项目致力于研究SU(3)自旋轨道耦合导致的新物态和新奇拓扑元激发。我们提出了在超冷原子系统实现SU(3)自旋轨道耦合的实验方案；在超冷原子自旋轨道耦合系统中预言了具有自发旋转粒子流的手性超固态；预言了Aharonov-Bohm几何相位在超冷原子气体中的新效应；理论预言了SU(3)自旋轨道耦合导致的二维晶格超固态和双量子自旋涡旋。这些结果为基于超冷原子的量子模拟和探索非传统量子流体动力学开辟了新的道路。