One-Dimensional Gases of Dysprosium

一维镝气体

• 批准号: 1707336
• 负责人: Benjamin Lev
• 金额: $ 48.7万
• 依托单位: Stanford 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 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1707336&HistoricalAwards=false
• 关键词: Dimensional; Gases; Dysprosium

This project will study the interface between quantum mechanics and thermodynamics. This is a cutting edge research direction because the way quantum systems come into equilibrium, or "thermalize", remains a mystery. The picture is clearer for isolated classical systems. For example, in classical dynamics if a system of interacting particles explores all possible configurations, then it can thermalize. Such a system is also said to be "chaotic" and to lack "integrability", which means the particle trajectories cannot be predicted with a sequence of integrals. For integrable systems, future dynamics can be predicted. Interestingly, however, if the conditions for integrability are weakly broken, there are still scenarios for which stable dynamics can be predicted. This is a consequence of the celebrated Kolmogorov-Arnold-Moser (KAM) theorem, which shows that small perturbations are insufficient to render the system chaotic. This effect is largely responsible for the orbital stability for our own solar system. Since quantum physics describes dynamics too, it is natural to ask if there is an analogue to the KAM theorem for quantum systems. This project will explore this question by first creating a quantum integrable system using a gas of ultracold atoms confined in one-dimensional traps. Changes to the system's behavior will then be caused by adjusting magnetic long-range interactions between the atoms. The time it takes for the gas to thermalize after a momentum kick will provide a measure of the breakdown of integrability in the system. This work will have an impact on quantum information processing, and other technologies that rely on the predictability of quantum dynamics. Students working on this project will also benefit from research training that will prepare them for jobs in high tech industry or academic careers.To achieve these goals, this team will confine atoms of dysprosium (Dy), the most magnetic element, in two-dimensional optical lattices. The energy gap to the first transverse motional excited state will be larger than the gas temperature and chemical potential, ensuring that the gas in each cigar-shaped tube is in the quasi-1D regime. For large-enough scattering lengths, the gas will approximately realize the Tonks-Girardeau limit of the integrable Lieb-Liniger model. A magnetic field will set the angle of the dipoles with respect to the tube axis. The magnitude of the magnetic dipole-dipole interaction can be tuned by this angle, allowing us to control the integrability-breaking perturbation strength. A Bragg diffraction pulse will split the gas in two. These parts of the gas will collide every 10 ms due to weak longitudinal harmonic confinement. This dipolar version of the quantum Newton's cradle experiment will allow this team to explore analogs of the classical KAM scenario in the quantum realm. Moreover, spin-orbit coupling (previously demonstrated by this group with Dy) will be introduced in attempts to induce p-wave superfluidity near Feshbach resonances in one-dimensional gases of fermionic Dy. In this way, one-dimensional atomic systems will be used to explore novel types of superfluids that arise when the spin of the atom depends on the direction the atom is moving. This is important because exotic superfluids such as these support unusual excitations that may be useful for quantum information processing.

该项目将研究量子力学和热力学之间的接口。 这是一个尖端的研究方向，因为量子系统达到平衡或“热化”仍然是一个谜。 对于孤立的古典系统，图片更清晰。 例如，在经典动力学中，如果一个相互作用的粒子系统探索了所有可能的配置，则可以热化。 这种系统也被称为“混乱”，缺乏“集成性”，这意味着无法用一系列积分来预测粒子轨迹。 对于可集成的系统，可以预测未来的动态。 然而，有趣的是，如果可集成性条件较弱，则仍然可以预测稳定的动态。 这是著名的Kolmogorov-Arnold-Moser（KAM）定理的结果，该定理表明，小型扰动不足以使系统混乱。 这种效果在很大程度上是我们自己的太阳系的轨道稳定性的原因。 由于量子物理学也描述了动力学，因此自然要询问量子系统是否有类似的量子定理。 该项目将首先使用限制在一维陷阱中的超低原子的气体创建量子集成系统来探索这个问题。 然后，通过调整原子之间的磁长距离相互作用来引起系统行为的变化。 动量踢后，气体对气体进行热化所需的时间将提供系统中可集成性的分解的度量。 这项工作将对量子信息处理以及依赖量子动态可预测性的其他技术产生影响。 从事该项目的学生还将受益于研究培训，这将使他们在高科技行业或学术职业中为工作做好准备。 第一个横向运动激发态的能量间隙将大于气体温度和化学电位，从而确保每个雪茄形管中的气体在准1D状态下。 对于大型散射长度，气体将大致实现可集成的Lieb-Liniger模型的Tonks-Girardeau极限。 磁场将相对于管轴设置偶极子的角度。 磁偶极 - 偶极相互作用的大小可以通过此角度调节，从而使我们能够控制破坏性的扰动强度。 Bragg衍射脉冲将使气体分为两分。 由于纵向谐波限制弱，气体的这些部分将每10毫秒碰撞一次。 量子牛顿的摇篮实验的偶性版本将使该团队能够探索量子领域中经典kam场景的类似物。 此外，将引入自旋轨道耦合（以前由DY组证明），以试图在一维费米米型DY中诱导Feshbach共振附近的P波超流体。 这样，一维原子系统将用于探索当原子的旋转取决于原子在移动的方向时，出现的新型超流体类型。 这很重要，因为诸如这些的异国情调超流体支持可能对量子信息处理有用的异常激发。