Exploring Excited-State 1D Dipolar Quantum Matter with Dysprosium Gases

普通观众摘要：这个研究项目建立在PI和他的学生在NSF先前的支持下组装的机器上-这个设备激励了世界各地的研究小组开发他们自己的类似实验。利用这台设备，PI正在探索受光约束的新型受激发量子气体，只在一维上运动。这些气体-镝-是所有元素中最具磁性的。这使得该团队能够利用镝原子之间巨大的棒状磁铁相互作用来揭示奇异的量子物理。限制气体在一个维度上运动会导致奇怪的现象。例如，原子通常要么是玻色子(自旋为整数)，要么是费米子(自旋为半整数)，但在一维中，玻色子可以像费米子一样，反之亦然。此外，固有的大量子效应阻止了像完美晶体那样在长时间尺度上具有有序的相的出现。将这种气体激发到更高的能级应该会产生更奇怪的效应，但这些效应在很大程度上还没有被探索出来。PI和他的团队致力于创造这样的气体，因为他们怀疑这些量子系统不会热化-也就是，与咖啡和牛奶混合形成棕色液体不同，激发的气体不会进入任何“混合”的热平衡。这样的系统可能会教会我们如何通过抑制所有破坏信息的热化过程来保护存储在量子气体或材料中的量子信息。更广泛地说，这个研究项目通过推动原子物理、量子光学和凝聚态物理的实验最先进的技术来探索强关联物质的未知区域。因此，这项研究计划为研究生和本科生提供了一个特殊的培训环境，由斯坦福大学和PI最先进的激光实验室提供的形成性科学环境。这项研究涉及物理和技术技能，这些技能在各种重要的技术领域都有应用，最著名的是用于电信的激光和光子学，以及用于电子设备的先进新型固态材料。技术观众摘要：限制在一维范围内的镝的不同寻常的性质可能会产生各种奇异的量子多体相和非平衡动力学。PI和他的学生正在通过使用他们独特的实验系统来解决非平衡一维偶极气体物理学的新方面，从而扩展量子模拟的前沿。这些系统允许PI的团队触及量子物理中热化的鲜为人知的方面。例如，关于量子可积性的崩溃和高激发态量子多体系统的稳定性，仍有许多有待研究的问题。本计划资助了两个基于一维偶极气体的新活动：PI和学生：1)研究偶极相互作用如何改变Luttinger-Liquid-like基态和激发态，可能稳定后者的崩溃，从而产生新的“量子多体SCAR”态；2)将他们在玻色偶极量子牛顿摇篮上的工作扩展到费米子，研究量子热化如何依赖于量子交换统计；以及3)探索在1D中存在远程偶极相互作用的情况下多体本地化的可能崩溃。该奖项反映了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。

General audience abstract:This research program is built on the machine the PI and his students assembled under prior NSF support---this apparatus has inspired research groups worldwide to develop their own similar experiments. With this apparatus, the PI is exploring new types of excited quantum gases constrained by light to move in only one dimension. These gases---of dysprosium---are the most magnetic of any element. That allows the team to exploit the large, bar-magnet-like interaction between the dysprosium atoms to reveal exotic quantum physics. Constraining the gas to move in one dimension results in bizarre phenomena. For example, atoms are normally either bosons (with integer spin) or fermions (with half-integer spin), but in one dimension, bosons can act like fermions and vice versa. Moreover, inherently large quantum effects prevent phases from emerging that possess order at long length scales, like perfect crystals do. Exciting such gases to higher energy states should yield even stranger effects, but these are largely unexplored. The PI and his team aim to create such gases because they suspect these quantum systems will not thermalize---i.e., unlike how coffee and milk mix to form a brown liquid, the excited gas will not come into any “mixed-like” thermal equilibrium. Such systems may teach us how to protect stored quantum information in quantum gases or materials by inhibiting all information-destroying thermalization processes. More generally, this research project explores uncharted regimes of strongly correlated matter by pushing the experimental state-of-the-art in atomic physics, quantum optics, and condensed matter physics. As such, this research program provides an exceptional training ground for graduate and undergraduate students in the formative scientific environment provided by Stanford University and the PI’s state-of-the-art laser lab. The research concerns physics and technical skills that find application in a variety of significant areas of technology, most notably lasers and photonics for telecommunications and advanced novel solid-state materials for electronic devices. Technical audience abstract:A diversity of exotic quantum many-body phases and nonequilibrium dynamics may arise from the unusual properties of dysprosium confined to one dimension. The PI and his students are extending the frontier of quantum simulation by using their unique experimental system to address novel aspects of the physics of out-of-equilibrium 1D dipolar gases. These systems allow the PI’s team to touch on poorly understood aspects of thermalization in quantum physics. For example, much remains to be learned about both the breakdown of quantum integrability and the stabilization of highly excited quantum many-body systems. The present program funds two new activities based on 1D dipolar gases; the PI and students are: 1) studying how dipolar interactions modify Luttinger-liquid-like ground and excited states, possibly stabilizing the latter against collapse to yield novel `quantum many-body scar'-like states; 2) extending their work on bosonic dipolar quantum Newton's cradles to fermions to ask how quantum thermalization depends on quantum exchange statistics; and 3) exploring the possible breakdown of many-body localization in the presence of long-range dipolar interactions in 1D.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.