Study of Electrons in Superfluid Helium

* 非技术摘要 * 气泡在液体中的形成是许多不同过程的结果。它们可以在含有气体的液体上的压力降低时产生，例如当一罐可口可乐被打开时。气泡也会在船的螺旋桨周围的湍流中形成，或者当液体被加热到沸点以上时形成。在某些情况下，气泡的产生具有不期望的效果。例如，随着时间的推移，在船的螺旋桨附近产生的气泡会损坏螺旋桨。 另一方面，气泡的产生也可以是非常有用的，如在超声波清洁器中。本研究的长期目标是研究泡沫是如何形成的，以及如何控制泡沫的形成以获得技术优势。将进行实验，以研究在一些不同的条件下，在液氦气泡的产生。之所以选择液氦进行这些实验，是因为它可以以特殊的纯度生产，因此可以控制或消除液体中杂质可能产生的影响。该研究项目将有助于满足国家对在光学、低温学、流体力学和计算机模拟等重要技术领域受过培训的科学家的需求。技术摘要 * 注入液氦的电子迫使打开一个小空腔，产生半径为2 nm的“电子泡”。这个个人研究者奖支持的研究，包括几个项目，以研究这些气泡，并利用它们来调查量子化漩涡的属性。第一个项目将是研究“外来离子”，即结构未知的电子气泡，它们比正常气泡小。在第二个项目中，将研究电子泡，其中电子已被光学激发到1D量子态。第三个项目是将电子泡附着在量子化的涡旋上，通过对这些电子成像，研究涡旋的运动。这项工作是令人兴奋的，因为电子泡是独特的量子系统，其大小和形状由电子的量子态决定。他们的研究可以回答量子力学中有关测量过程性质的基本问题。这项研究是实验和理论的结合，包括与巴黎和巴塞罗那的小组合作。 将这些要素有机结合起来，是培养研究生和本科生的一种很好的手段。

****NON-TECHNICAL ABSTRACT****Bubbles form in liquid as a result of a number of different processes. They can be produced when the pressure on a liquid that contains gas is reduced, when a can of Coca Cola is opened, for example. Bubbles also form in the turbulence around the propeller of a ship or when a liquid is heated above its boiling point. In some situations, bubble production has undesirable effects. For example, over the course of time the bubbles produced near the propeller of a ship, damage the propeller. On the other hand, bubble generation can also be very useful, as in an ultrasonic cleaner. The long-range goal of this research is the study of how bubbles are formed and how to control the formation for technological advantage. Experiments will be performed to investigate bubble production in liquid helium under a number of different conditions. Liquid helium is chosen for these experiments because it can be produced with exceptional purity, and so effects that might arise from impurities in the liquid can be controlled or eliminated. The research project will contribute to the national need for scientists trained in the technically important fields of optics, cryogenics, fluid mechanics and computer simulation.****TECHNICAL ABSTRACT****An electron injected into liquid helium forces open a small cavity, producing an "electron bubble" of radius 2 nm. This individual investigator award supports research that includes several projects to study these bubbles and to use them to investigate the properties of quantized vortices. The first project will be to investigate the "exotic ions", electron bubbles of unknown structure that are smaller than normal bubbles. In a second project a study will be made of electron bubbles in which the electron has been optically excited to the 1D quantum state. The third project is to attach electron bubbles to quantized vortices and by imaging these electrons, study the motion of the vortices. This work is exciting because electron bubbles are unique quantum systems with a size and shape of the bubble determined by the quantum state of the electron. Their study can answer fundamental questions concerning the nature of the measurement process in quantum mechanics. The research is a combination of experiment and theory, and includes collaboration with groups in Paris and Barcelona. With the combination of these components, the research is an excellent means for the training of graduate students and undergraduates.