RUI: Quantum Turbulence in Atomtronic Systems

“原子电路”是一种薄薄的原子气体，通过用激光挤压它并将其冷却到接近绝对零度的温度，它被限制在二维范围内。这种受限气体的低温增强了组成原子的波状量子力学性质的展示，因此它们形成了一种被称为玻色-爱因斯坦凝聚体(BEC)的状态。处于BEC状态的水平薄层气体可以通过限制激光模塑成类似于闭合电路的任意闭合回路形状。然后，气体可以被激光搅动，这样它就像电路中的电子一样在闭合回路中流动，只是粒子是中性原子。因此，“原子电子学”是一种电子学的类比，整个原子都在电路中流动。原子子系统之所以令人感兴趣，是因为它们可能被用作极其灵敏的旋转、磁场和引力场的量子传感器。这项研究计划将研究如何利用这些气体搅拌时经常出现的量子湍流来增强这些量子传感器设备的运行。将开发读出这些电路的重要特性的方法(例如电路中的电流表和电压表的模拟)。这项工作是与RUI研究所的本科生一起完成的，与JQI/NIST的实验研究人员密切合作。合作将研究强烈限制在水平面中的原子气体超冷样品的行为，这些样品受到激光产生的任意空间和时间相关势的影响。这项研究将利用最近在光学操纵超冷气体方面的实验突破来设计新的原子电路势。在这项工作中，我们将研究各种不同的原子电路设计。要研究的每个原子电路将被凝聚成BEC的原子完全填充。将研究产生凝析液流的方法，特别是流畅的方法。将模拟每个原子电路在零温度和非零温度下的运行。原子电路中的流动经常涉及到许多拓扑激励的出现，如涡旋(即气体中的微型龙卷风)和孤子(运动而不退化的孤立波)，因此表现出“量子湍流”。这项研究的重点之一将是检测所有此类刺激的存在，然后跟踪和分析它们的行为。这些研究将使发展原子系统中的涡旋和孤子行为的简单模型成为可能。这样的模型将有助于为应用设计性能最佳的原子电路。这项研究计划将使至少两名本科物理专业的学生在超冷原子理论领域获得最先进的研究经验。该项目将通过加强一个本科机构(GA Southern)、一个国家实验室(NIST)和一个主要研究型大学(马里兰大学)之间业已建立的合作，来加强研究和教育的基础设施。这项研究的结果将通过开发虚拟现实(VR)视频来广泛传播，以增进对科学和技术的了解，这些视频在普通公众可访问的水平上描述BEC的物理。这些VR视频将适合在Oculus Rift和Google Cardboard等VR头盔上展示。最后，了解量子湍流在原子电路中的作用将有助于设计新一代实用设备，这些设备将在计量学和导航中得到应用。这些知识还将增加对量子物质基本性质的理解。

An "atom circuit" is a thin sheet of atomic gas that has been confined to two-dimensions by squeezing it with laser light and cooling it to nearly the absolute zero of temperature. The low temperature of such confined gases enhances the display of the wave-like quantum mechanical nature of the constituent atoms so that they form a state called a Bose-Einstein condensate (BEC). A horizontal thin sheet of gas in the BEC state can be molded by the confining laser light into arbitrary closed-loop shapes analogous to closed electric circuits. The gas can then be stirred by lasers so that it flows around the closed loop like the electrons in an electric circuit except that the particles are neutral atoms. "Atomtronics" is accordingly an analogue of electronics in which entire atoms flow through a circuit. Atomtronic systems are of interest because they could potentially be used as extremely sensitive quantum sensors of rotations, of magnetic fields, and of gravitational fields. This research program will study how the quantum turbulence that often appears when such gases are stirred can be harnessed to enhance the operation of these quantum sensor devices. Methods for readout of the important characteristics of these circuits (such as analogs of ammeters and voltmeters in electric circuits) will be developed. This work, performed with undergraduate students at an RUI institution, is conducted in close collaboration with experimental researchers at JQI/NIST.The collaboration will study the behavior of ultracold samples of atomic gases strongly confined in a horizontal plane and subjected to arbitrary space-dependent and time-dependent potentials produced by laser light. The research will take advantage of recent experimental breakthroughs in the optical manipulation of ultracold gases in designing new atom circuit potentials. In this work a variety of different atom-circuit designs will be investigated. Each atom circuit to be studied will be assumed to be completely filled by the atoms condensed into a BEC. Methods of producing condensate flow, especially smooth flow, will be studied. The operation of each atom circuit will be simulated both at zero and non-zero temperature. The flow present in atom circuits often involves the appearance of numerous topological excitations such as vortices (i.e., miniature tornadoes in the gas) and solitons (solitary waves that move without degrading) and thus exhibits "quantum turbulence". One focus of this research will be to detect the presence of all such excitations and then follow and analyze their behavior. These studies will enable the development of simple models of vortex and solitonic behavior in the atomtronic systems. Such models will be useful in designing optimally performing atom circuits for applications. This research program will enable at least two undergraduate physics majors to gain state-of-the-art research experience in the area of ultracold atom theory. The project will enhance the infrastructure for research and education by enhancing an established collaboration among an undergraduate institution (GA Southern), a national laboratory (NIST), and a major research university (University of Maryland). Results of this research will be broadly disseminated to enhance scientific and technological understanding by developing virtual reality (VR) videos that describe the physics of BECs at a level that is accessible to the lay public. These VR videos will be suitable for display on VR headsets such as the Oculus Rift and Google Cardboard. Finally, an understanding of the role of quantum turbulence in atom-circuits will enable the design of a new generation of practical devices that will find applications in metrology and navigation. This knowledge will also add to the understanding of the fundamental properties of quantum matter.