Study of Electrons in Superfluid Helium

****非技术摘要****气泡在液体中形成是许多不同过程的结果。当含有气体的液体的压力降低时，例如打开一罐可口可乐时，就会产生这种气体。在船舶螺旋桨周围的湍流中，或者当液体加热到沸点以上时，也会形成气泡。在某些情况下，泡沫的产生会产生不良影响。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，如在超声波清洗机。本研究的长期目标是研究气泡是如何形成的，以及如何控制气泡的形成以获得技术优势。将进行实验来研究在许多不同条件下液氦中的气泡产生。之所以选择液氦进行这些实验，是因为它的纯度极高，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训练的科学家的需求。****技术摘要****注入液氦的电子迫使打开一个小腔，产生半径为2nm的“电子泡”。这个个人研究者奖支持的研究包括几个项目来研究这些气泡，并利用它们来研究量子化漩涡的特性。第一个项目将是研究“外来离子”，即比普通气泡小的结构未知的电子气泡。在第二个项目中，将对电子气泡进行研究，其中电子被光学激发为一维量子态。第三个项目是将电子气泡附着在量子化的漩涡上，并通过对这些电子成像，研究漩涡的运动。这项工作令人兴奋，因为电子泡是一种独特的量子系统，其大小和形状由电子的量子态决定。他们的研究可以回答有关量子力学中测量过程本质的基本问题。这项研究是实验和理论的结合，包括与巴黎和巴塞罗那的团队合作。这些组成部分相结合，研究是培养研究生和本科生的一个很好的手段。

****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.