Acoustic Birefringence and Superfluid 3He

该项目将进一步加深我们对一系列广泛的科学学科（包括量子流体和材料物理学）相当感兴趣和重要的材料的理解。主要目标是在声学法拉第效应发现的基础上开发新的声学技术。法拉第效应是去年发现的，其效应与迈克尔·法拉第在1845年发现的重要磁光效应非常相似。本研究将利用基于这些声学原理的技术，将超流体3He的阶参量模式光谱提高几个数量级。这些实验将为超流体本身的性质以及产生超流体的配对机制提供新的重要信息。将寻求新的超流体集体模态，这些超流体集体模态在理论上已经被预测过，并且可以用新的实验方法来识别。提出的工作的第二个目标是研究杂质散射效应，它可以抑制3He中的超流动性。这将对研究3He中不寻常的超流体行为提供重要的见解，并为如何控制超流体抑制提供建议。最近发现了新的相和不寻常的性质，但与目前的理论认识不一致。为了更好地利用超导性和超流动性，通过多孔硅气凝胶以可控的方式将杂质引入3He中，获得对3He的这种理解是非常重要的。本科生，研究生和一些高中项目将是这项研究的一部分。当地的两名高中学生正计划以他们在低温实验室的经验为基础，为全国英特尔竞赛准备项目。教师、博士后和研究生对这些项目的监督是一种独特而互利的经历。拟议的研究将加深对一类重要材料的理解，这些材料对我们的社会和基础科学知识的应用具有重要的前景。它们被称为非常规量子系统。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学光谱学，使用的技术类似于过去50年来在半导体材料领域非常重要的光学技术。该研究将利用新的声学原理将超流体3He的阶参量集体模谱提高几个数量级。这些实验将揭示超流体的性质及其产生的物理机制。由于这种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。当地的两名高中学生正计划以他们在大学实验室的经验为基础，准备参加全国英特尔竞赛的项目。教师、博士后助理和研究生的研究活动与这些高中项目的整合将是一个独特而互利的经历。

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.