Acoustic Birefringence and Superfluid 3He

这个项目将进一步加深我们对广泛的材料类别的理解，这些材料对包括量子流体和材料物理在内的广泛的科学学科非常感兴趣和重要。主要目标是在发现声学法拉第效应的基础上开发新的声学技术，法拉第效应是去年发现的一种与迈克尔·法拉第在1845年发现的重要磁光效应完全相似的效应。提出的研究将利用基于这些声学原理的技术将超流3He中的序参数模的光谱提高几个数量级。这些实验将提供有关超流体本身的性质以及产生它的配对机制的新的重要信息。我们将寻找新的超流集体模式，这些模式已经在理论上得到了预测，并且可以从新的实验方法中识别出来。这项工作的第二个目标是研究可以抑制3He中过剩流动的杂质散射效应。这将对3He中异常的超流行为提供重要的认识，并对如何控制超流抑制提出建议。最近发现了新的相和不寻常的性质，但这与目前的理论认识并不一致。为了更好地利用超导电性和超流性，通过非常多孔的二氧化硅气凝胶以可控的方式引入3He中的杂质来获得对3He的理解是非常重要的。本科生、研究生和一些高中项目将是这项研究的一部分。两名当地高中生正计划根据他们在这个低温实验室的经验，为全国英特尔大赛准备项目。将教师、博士后助理和研究生的指导与这些项目相结合是一种独特的、互惠互利的体验。拟议的研究将加深对一类重要材料的理解，这类材料在我们的社会和基本科学知识中具有重要的应用前景。它们被称为非传统量子系统。这一类包括超导材料，它们的成功应用需要开发新的测量工具。该项目的主要目标是开发一种新的声谱学，使用类似于过去50年来在半导体材料领域非常重要的光学技术的技术。这项研究将利用新的声学原理将超流3He中的有序参数集体模谱提高几个数量级。这些实验将揭示超流体的性质和产生它的物理机制。由于这一材料是这一重要类别中所有材料的优秀代表，因此可以预期拟议的工作将对其应用产生广泛的影响。第二个目标是确定超导和超流体行为对杂质的敏感性。这一结果将为更好地利用超导电性铺平道路。本科生、研究生和一些高中项目将是这项研究的一部分。两名当地高中生正计划根据他们在大学实验室的经验，为全国英特尔大赛准备项目。将教师、博士后助理和研究生的研究活动与这些高中项目相结合，将是一种独特的互惠互利的体验。

This project will further our understanding of a broad class of materials of considerable interest and importance to a wide range of scientific disciplines including quantum fluids and materials physics. The main goal is to develop new acoustic techniques based on the discovery of the Acoustic Faraday Effect, a discovery made last year of an effect strictly analogous to the important magneto-optic effect discovered by Michael Faraday in 1845. The proposed research will improve the spectroscopy of order parameter modes in superfluid 3He by several orders of magnitude using the techniques based on these acoustic principles. These experiments will give new and important information on the nature of the superfluid itself as well as on the pairing mechanisms that give rise to it. New collective modes of the superfluid will be sought which have been predicted theoretically and which can be identified from the new experimental methods. A second goal of the proposed work is to study impurity scattering effects which can suppress superfluidity in 3He. This will give important insight into the unusual superfluid behavior in 3He and suggest how to control the superfluid suppression. New phases and unusual properties have recently been discovered but which are not consistent with present theoretical understanding. To pave the way for better use of superconductivity as well as superfluidity it is very important to gain this understanding in 3He using impurities introduced into 3He in a controlled manner by means of very porous silica aerogel. Undergraduate students, graduate students, and some high school projects will be part of this research. Two local high school students are planning to prepare projects for the national Intel competition based on their experience in this low temperature laboratory. The integration of supervision from faculty, postdoctoral associates, and graduate students with these projects is a unique and mutually beneficial experience. %%%The proposed research will develop understanding of an important class of materials holding significant promise for applications to our society and for basic scientific knowledge. They are called unconventional quantum systems. This class includes superconducting materials for which their successful application requires development of new measurement tools. The main goal of the project is to develop a new acoustic spectroscopy using techniques similar to optical techniques that have been so important in the past 50 years in the semiconductor-materials field. The proposed research will improve the spectroscopy of order parameter collective modes in superfluid 3He by several orders of magnitude using the new acoustic principles. The experiments will reveal the nature of the superfluid and the physical mechanisms responsible for it. Since this material is an excellent representative of all materials in this important class it can be expected that there will be broad impact on their applications resulting from the proposed work. A second goal is to determine the sensitivity to impurities of the superconducting and superfluid behaviors. The results will pave the way for better use of superconductivity. Undergraduate students, graduate students, and some high school projects will be part of this research. Two local high school students are planning to prepare projects for the national Intel competition based on their experience in the university laboratory. The integration of research activity from faculty, postdoctoral associates, and graduate students with these high school projects will be a unique and mutually beneficial experience.