Two-Dimensional Quantum Turbulence in Bose-Einstein Condensates

在一个散装流体的流体动力学湍流之间的区别，并在一个其流动被限制为两个维度，是在小长度尺度的能量耗散一般被抑制在后者。 在小长度尺度的能量和涡度强迫下，进入二维（2D）流体，因此能量被转移到更大的尺度，与体相流体中的湍流相反。 最明显的是，这意味着涡流和漩涡可能合并形成更大的漩涡。 二维量子湍流（2DQT）涉及量子流体（如原子玻色-爱因斯坦凝聚体（BEC））中二维湍流的研究。在这个新兴的研究领域，许多悬而未决的问题一般涉及到量子化的超流体中的涡旋动力学和动能在长度尺度之间的分布。 例如，在2DQT流动中，是否会像Onsager在1949年最初预测的那样，自然地出现相同环流的量子化涡旋簇？ 该NSF奖项支持旨在了解2DQT中涡旋分布，涡旋动力学和能谱之间关系的新实验。 针对这些主题的研究实验计划将利用高度扁的BEC构建一个新的成像系统，旨在观察BEC内的涡流动力学，开发按需涡流生成和操纵方法，以自下而上的方法研究湍流中的涡流相互作用，超流体如稀气体玻色-爱因斯坦凝聚体具有显著的性质，包括无摩擦流动和只有通过形成许多称为涡旋的微观量子池才能获得的流体循环。这些涡旋在整个超流体中的分布和动力学提供了有关湍流等流体现象的信息。 该项目研究量子涡旋的产生，并跟踪它们在煎饼状冷凝物中的动力学，作为理解超流体中二维湍流特性的一种手段。已知经典流体中的湍流与超流体中的量子湍流有相似之处，但对于二维流动的特定情况，量子和经典情况之间的相似性和差异尚不清楚。该补助金支持研究和研究生指导和培训，涉及在凝聚体中创建，操纵和检测量子涡旋的新方法，并探索这些超流体中二维湍流的特性。通过对二维量子湍流的受控研究，我们的目标是对涡旋相互作用和其他湍流现象提出新的见解，这是物理学中最具挑战性和最复杂的课题之一。

A distinction between hydrodynamic turbulence in a bulk fluid, and in one whose flows are restricted to two dimensions, is that energy dissipation at small length scales is generally inhibited in the latter. Under small-length-scale forcing of energy and vorticity into a two-dimensional (2D) fluid, energy is therefore transferred towards larger scales, opposite that of turbulence in a bulk fluid. Most conspicuously, this means that eddies and vortices may merge to form even larger vortices. Two-dimensional quantum turbulence (2DQT) involves the study of 2D turbulence in quantum fluids such as atomic Bose-Einstein condensates (BECs). In this emerging field of research, numerous open questions generally relate to the dynamics of quantized vortices in superfluids and to the distribution of kinetic energy among length scales. For example, do clusters of quantized vortices of identical circulation naturally emerge in 2DQT flows, as initially predicted by Onsager in 1949? This NSF award supports new experiments aimed at understanding the relationships between vortex distributions, vortex dynamics, and energy spectra in 2DQT. The experimental program of research targeting these topics will utilize highly oblate BECs for the construction of a new imaging system designed to observe vortex dynamics within a BEC, the development of on-demand vortex generation and manipulation methods to study vortex interactions in turbulence with a bottom-up approach, and the study and characterization of developed 2DQT in BECs.Superfluids such as dilute-gas Bose-Einstein condensates have remarkable properties, including frictionless flow and fluid circulation that is obtained only by the formation of many microscopic quantum whirlpools known as vortices. The distribution and dynamics of these vortices throughout the superfluid provide information on fluid phenomena such as turbulence. This project is studying the generation of quantum vortices and follows their dynamics in pancake-shaped condensates as a means to understand the characteristics of two-dimensional turbulence in superfluids. Turbulence in classical fluids is known to share similarities with quantum turbulence in superfluids, but for the specific case of two-dimensional flows, the similarities and differences between the quantum and classical cases are unclear. This grant supports research and graduate-student mentoring and training involving new methods of creating, manipulating, and detecting quantum vortices in condensates, and probes the characteristics of two-dimensional turbulence in these superfluids. Through controlled studies of two-dimensional quantum turbulence, our aim is to develop new insights on vortex interactions and other phenomena of turbulence, one of the most challenging and complex topics in physics.