Dynamics and Excitations of Spin-Orbit-Coupled Bose-Einstein Condensates

自旋轨道耦合玻色-爱因斯坦凝聚体的动力学和激发

• 批准号: 1708134
• 负责人: Yong Chen
• 金额: $ 30万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708134&HistoricalAwards=false
• 关键词: Dynamics; Excitations; Spin; Orbit; Coupled

Quantum many-body interactions are responsible for material properties such as magnetism and conductivity. Understanding how these properties depend on a material's structure, its temperature, and the motion of electrons in the material is important for developing new technologies, for example those using superconductivity or "spintronics". This project will investigate many-body interactions in model systems using ultracold atoms in synthetic potentials generated by laser light. Lasers will couple the motion and "spin" of atoms, to cause spin-orbit-coupling (SOC) analogous to the relativistic SOC effects that are important in many electronic materials. This project will focus on the experimental studies of how SOC affects quantum transport phenomena and collective excitations in an atomic Bose-Einstein condensate (BEC). A BEC is a coherent superfluid phase that occurs at sufficiently low temperatures in a quantum gas. Understanding how SOC affects spin transport in BEC will provide helpful guidance for designing novel "spintronic" devices that aim to use spin (quantum mechanical angular momenta) to carry and process information with much higher efficiency and lower energy consumption than current charge-based electronics. The study will lead to new insights that will help scientists understand and discover new types of superfluids and superconductors in which the interaction of particles of different spins are important. This project will also enhance collaborations between this experimental group and several theorists active in the field, and train students in physics and engineering to participate in interdisciplinary research involving atomic physics, quantum physics, condensed matter physics, and optics.This experimental research program will study an atomic (Rb-87) Bose-Einstein condensate (BEC) subject to optically (Raman) generated synthetic gauge fields and spin-orbit coupling (SOC). The study will focus on quantum dynamics, transport and excitations in spin-orbit-coupled (SOC) BEC. The study builds upon the team's recent achievements including the demonstration of a tunable Landau-Zener transition between the dressed bands in SOCBEC, and the realization of the Landau-Zener- Stueckelberg interference (atom interferometry in quasi-momentum space) and a new type of SOC with novel spin-momentum locking using "2nd generation dressed bands" induced by modulated Raman coupling. The current program will study in particular various spin-dependent transport and excitations. One example is the "spin dipole mode" (alternating spin current) that can be used to probe not only the spin transport but also collisions and thermalization of SOCBEC in the presence of such collective excitations. Another example is the so called scissors mode and spin-scissors mode that can be used to probe superfluidity and how it may be modified by SOC and synthetic magnetic fields. The later part of the program will also investigate low-dimensional (especially 1D) SOC BEC by adding an optical lattice, where the SOC is expected to have even more pronounced effects (such as to alter the ground state, interactions and excitations). This work may provide insights to engineer new states of matter (topological phases, novel superfluids) and to understand the spin transport and dynamics in SOC systems, which are important in spintronics.

量子多体相互作用决定了材料的性质，如磁性和导电性。 了解这些性质如何取决于材料的结构，温度和材料中电子的运动对于开发新技术非常重要，例如使用超导性或“自旋电子学”的技术。 本项目将研究模型系统中的多体相互作用，该模型系统使用激光产生的合成势中的超冷原子。 激光将耦合原子的运动和“自旋”，以引起自旋轨道耦合（SOC），类似于在许多电子材料中很重要的相对论SOC效应。 本项目将着重于SOC如何影响原子玻色-爱因斯坦凝聚体（BEC）中的量子输运现象和集体激发的实验研究。 BEC是在量子气体中在足够低的温度下发生的相干超流相。了解SOC如何影响BEC中的自旋输运，将为设计新型“自旋电子”器件提供有益的指导，这些器件旨在利用自旋（量子力学角动量）以比当前基于电荷的电子器件更高的效率和更低的能耗来携带和处理信息。 这项研究将带来新的见解，有助于科学家理解和发现新型超流体和超导体，其中不同自旋粒子的相互作用很重要。 该项目还将加强该实验组与活跃在该领域的几位理论家之间的合作，并培养物理学和工程学学生参与涉及原子物理学，量子物理学，凝聚态物理学，这个实验研究计划将研究原子（Rb-87）玻色-爱因斯坦凝聚体（BEC）受到光学（拉曼）产生的合成规范场和自旋轨道耦合（SOC）。研究将集中在自旋轨道耦合（SOC）BEC中的量子动力学，输运和激发。 该研究建立在该团队最近的成就基础上，包括SOCBEC中修饰带之间的可调谐Landau-Zener跃迁的演示，以及Landau-Zener- Stueckelberg干涉（准动量空间中的原子干涉）的实现和一种新型的SOC，该SOC具有由调制拉曼耦合引起的“第二代修饰带”。目前的计划将特别研究各种自旋相关的输运和激发。一个例子是“自旋偶极模式”（交变自旋电流），它不仅可以用来探测自旋输运，还可以探测在这种集体激发存在下SOCBEC的碰撞和热化。 另一个例子是所谓的剪刀模式和自旋剪刀模式，可以用来探测超流性以及它如何被SOC和合成磁场改变。 该计划的后半部分还将通过添加光学晶格来研究低维（特别是1D）SOC BEC，预计SOC将具有更显著的影响（例如改变基态，相互作用和激发）。这项工作可以提供见解工程新的物质状态（拓扑相，新的超流体），并了解自旋输运和动力学SOC系统，这是重要的自旋电子学。

项目成果

Spin current generation and relaxation in a quenched spin-orbit-coupled Bose-Einstein condensate

• DOI: 10.1038/s41467-018-08119-4
• 发表时间: 2018-10
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: Chuan-Hsun Li;C. Qu;R. Niffenegger;Su-Ju Wang;M. He;D. Blasing;Abraham J. Olson;C. Greene;Y. Lyanda-Geller;Qi Zhou;Chuanwei Zhang;Yong P. Chen