NSF-BSF: Rotating Ultracold Fermi Gases in a Box

流体在旋转容器中的行为长期以来一直是基础流体力学和应用流体力学的一个重要课题，包括在湍流研究中。当日常经典流体缓慢地旋转时，它们表现出众所周知的渐进旋转运动。量子流体对旋转的反应是截然不同的。低于一定的旋转频率，这些流体对其容器的旋转没有反应；如果它们旋转得足够快，就会出现称为漩涡的漩涡。这些涡旋具有明显的量子属性，是理解量子流体流体动力学的关键。特别是，量子流体的湍流主要由涡旋之间的相互作用以及涡旋激发与声波之间的相互作用所主导。研究量子流体中的湍流的主要动机之一是，由于量子涡旋的离散和明确的性质，它比更常见的经典流体的湍流更基本，并可以为理解后者提供蓝图。这个项目将通过使用超冷原子气体作为量子流体来解决这个问题。这些气体将被用光制成的盒子捕获，盒子由可编程的电光设备雕刻而成。利用这些装置的快速实时特性，超冷气体将被设置在旋转中，并将研究量子化涡旋的成核和这些涡旋的激发。在量子物质上放映几乎任意的“电影”的能力将预示着量子控制的一个新阶段，并向可编程的量子模拟又迈进了一步。该项目将支持对两名研究生进行原子物理现代技术和用光对量子物质的多功能控制的培训。均匀量子气体最近被证明是一类令人兴奋的新量子流体，具有明显的优势。这个项目将结合这些新的均匀气体和对原子陷阱的实时控制来研究教科书设置中的超流方面。这个项目将使用光盒捕获气体来研究强相互作用量子流体中超流的开始和涡旋细丝的集体激发。尽管进行了大量的实验和理论工作，但有关超流的几个基本问题仍然悬而未决。一个这样的平衡问题是强相互作用超流体中超流体密度、序参数和凝聚分数之间的关系。第二个不平衡的例子是作用在漩涡上的力的问题。这些力对超流体和量子流体的正常成分之间的相互摩擦以及涡流的质量产生了至关重要的影响。这些力量的计算显然存在争议。这个项目将研究亚临界和超临界旋转的机制。非平衡的三维单涡态将被用来研究涡旋的惯性质量问题和涡丝的各种集体激发的性质。Gross-Pitaveskii和Bogoliubov-de Gennes方程的数值模拟将通过测试光盒中的旋转协议以及激发和探测涡旋集体激发的机制来指导实验。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。

The behavior of fluids in rotating containers has long been a crucial topic in both fundamental and applied hydrodynamics, including in the study of turbulence. When everyday – classical - fluids are slowly set in rotation, they display a well-known progressive rotation motion. The response to rotation of quantum fluids is strikingly different. Below a certain rotation frequency, these fluids do not respond to the rotation of their container; if they are rotated sufficiently fast, swirling eddies called vortices appear. Those vortices have distinctly quantum properties, and are key to understanding the hydrodynamics of quantum fluids. In particular, the turbulence of quantum fluids is dominated by the interactions between vortices, and by the interactions between excitations of vortices and sound waves. One of the main motivations in studying turbulence in quantum fluids is that, because of the discrete well-defined nature of quantum vortices, it is more fundamental than the more common turbulence of classical fluids and could provide a blueprint for the understanding of the latter. This project will tackle this topic by using gases of ultracold atoms as quantum fluids. These gases will be trapped using boxes made of light, carved using programmable electro-optic devices. Exploiting these devices’ fast real-time characteristics, the ultracold gases will be set in rotation and the nucleation of quantized vortices and the excitations of these vortices will be studied. The ability to project nearly arbitrary “movies” on quantum matter will herald a new stage in quantum control and provide an additional step towards programmable quantum simulation. This project will support the training of two graduate students to modern techniques in atomic physics and the versatile control of quantum matter with light.Uniform quantum gases have recently proven to be an exciting new class of quantum fluids, with distinct advantages. This project will combine these novel uniform gases and real-time control of the atom traps to study aspects of superfluidity in textbook settings. This project will use optical-box trapped gases to study the onset of superfluidity in strongly interacting quantum fluids and the collective excitations of vortex filaments. Despite extensive experimental and theoretical efforts, several fundamental issues about superfluidity remain outstanding. One such equilibrium problem is the relation between superfluid density, the order parameter and the condensed fraction in a strongly interacting superfluid. A second, out of equilibrium, example is the problem of the forces acting on a vortex. Those forces have crucial consequences on the mutual friction between the superfluid and normal components of quantum fluids and on the mass of a vortex. The calculation of such forces is notably controversial. This project will investigate both the regime of sub-critical and supercritical rotation. Off-equilibrium three-dimensional single-vortex states will be produced and used to investigate problems of the inertial mass of a vortex and the nature of various collective excitations of vortex filaments. Numerical simulations of the Gross-Pitaveskii and the Bogoliubov-de Gennes equations will guide the experiments by testing rotation protocols in optical boxes as well as mechanisms to excite and probe the collective excitations of the vortices.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.