Exploring the Properties of Quantum Many-Body Scar States in Dipolar Gases

圆周率和研究生最近发现了著名的阿基米德螺丝的量子版本。自古以来，这种设备就被认为是一种将水(或谷物)输送到海拔高度上的设备，这种设备依赖于螺杆的手性属性：旋转螺杆，即使螺杆定期返回到相同的方向，也会沿一个方向移动水。该小组的量子阿基米德螺丝由被限制在一维光管中的原子组成。增加磁场使原子以周期性的增加和减少的概率相互散射，从而“转动”螺丝。这有助于将原子的能量泵送到越来越高的水平，就像传统的螺杆可以将水泵送到很高的高度一样。在过去，当尝试对非磁性原子进行这一操作时，螺杆崩溃-原子通过形成不需要的分子态从光管中掉出来。然而，PI和研究生们最近发现，具有强磁性并相互排斥的原子不会形成这些分子。这使得课题组首次完成了这些拓扑泵浦周期，并首次达到了所谓的“量子多体疤痕状态”。这项研究计划将探索这些SCAR态的性质，这些SCAR态是量子物质的非典型、高激发非热态。具体地说，将测量它们的动量分布，以更好地了解处于这些物质状态的原子之间关联的性质。PI和研究生还将快速压缩这些气体，以观察它们对极端条件的反应，这通常是了解更多物质量子态的好方法。研究这种状态可以让我们了解量子物质可能在远离超低温状态下存在的新方式。这些知识有助于指导该小组找到保护和存储量子信息的方法，以便在量子计算机或传感设备中使用。该项目将成为培养下一代量子工程师的绝佳训练场。此外，PI将首次在斯坦福大学开设勇士-学者项目的一个章节，以更好地将我们多样化和有才华的退伍军人人口融入高等教育项目。PI和研究生们将利用他们在拓扑泵浦的、偶极稳定的一维镝气体中发现的一种新型量子多体疤痕状态。该研究小组计划通过使用一种独特的实验系统来探索这些SCAR态的新特性，无论是在平衡中还是在非平衡中，从而扩展量子模拟的前沿。几乎可积的系统不会立即松弛到热平衡，但可以持续处于高度非热(预热)的稳定状态，其特征是突然出现的准粒子激发。在强相互作用可积系统中，准粒子的快度分布可以表现为不同于微观粒子的动量分布。本课题组已经具备了测量一维偶极量子气体快度分布的实验能力。PI和研究生将开展一项计划，利用动量和快度分布测量来探索这些偶极量子多体SCAR态的性质，包括稳态和远离平衡的猝灭。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The PI and graduate students recently discovered a quantum version of the famous Archimedes screw. Known from antiquity as a device to transport water (or grain) up elevations, the device relies on the “chiral” property of the screw: Rotating it moves water in one direction even though the screw periodically returns to its same orientation. The group’s quantum Archimedes screw consists of atoms confined into a one-dimensional tube of light. Increasing a magnetic field “turns” the screw by causing the atoms to scatter from each other with periodically increasing and decreasing probabilities. This serves to pump the atoms’ energy to higher and higher levels, just like the traditional screw can pump water up to great heights. In the past, when this was attempted with non-magnetic atoms, the screw collapsed---the atoms fell out of the light tube by forming unwanted molecular states. However, the PI and graduate students recently discovered that atoms that are strongly magnetic and set to repel each other do not form these molecules. That allowed the research group to complete these topological pumping cycles for the first time and reach so-called “quantum many-body scar states” for the first time. This research program will explore the properties of these scar states, which are atypical, highly excited non-thermal states of quantum matter. Specifically, their momentum distributions will be measured to better understand the nature of the correlations between the atoms when in these states of matter. The PI and graduate students will also rapidly compress these gases to observe their response to extreme conditions, which is often a good way to learn more about a quantum state of matter. Investigating such states can teach us about new ways in which quantum matter may exist away from regimes of ultralow temperatures. This knowledge helps guide the group toward methods to protect and store quantum information for use in a quantum computer or sensing device. This project will serve as an excellent training ground for the next generation of quantum engineers. Moreover, the PI will start a chapter of the Warrior-Scholar Project for the first time at Stanford to better integrate our diverse and talented veteran population into programs of higher education. The PI and graduate students will capitalize on their discovery of a new type of quantum many-body scar state in topologically pumped, dipolar-stabilized 1D gases of dysprosium. The research group plans to extend the frontier of quantum simulation by using a unique experimental system to explore the novel properties of these scar states, both in and out of equilibrium. Nearly integrable systems do not immediately relax to thermal equilibrium, but can persist in highly non- thermal (prethermal) steady states, characterized by the “rapidities” of emergent quasiparticle excitations. In strongly interacting integrable systems, the rapidity distribution of quasiparticles can behave differently from the momentum distribution of the microscopic particles. This research group has gained the experimental capability to measure the rapidity distributions of 1D dipolar quantum gases. The PI and graduate students will conduct a program to utilize both momentum and rapidity distribution measurements to explore the properties of these dipolar quantum many-body scar states, both in steady state and quenched far away from equilibrium.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.