Acoustic Birefringence and Superfluid 3He

声学双折射和超流体 3He

• 批准号: 0072350
• 负责人: William Halperin
• 金额: $ 45万
• 依托单位: Northwestern University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0072350&HistoricalAwards=false
• 关键词: Acoustic; Birefringence; Superfluid; 3He

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.

该项目将进一步加深我们对广泛的科学学科（包括量子流体和材料物理学）具有相当大的兴趣和重要性的广泛材料类别的理解。 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，该效应是去年发现的，与迈克尔法拉第在1845年发现的重要磁光效应非常相似。 建议的研究将提高频谱的序参量模式在超流3He的几个数量级，使用这些声学原理的基础上的技术。 这些实验将提供关于超流体本身的性质以及产生超流体的配对机制的新的重要信息，并将寻求新的超流体集体模式，这些模式已经在理论上得到预测，并可以通过新的实验方法得到确认。 建议的工作的第二个目标是研究杂质散射的影响，可以抑制3He的超流性。 这将对3He中不寻常的超流行为提供重要的见解，并建议如何控制超流抑制。 最近发现了新的相和不寻常的性质，但与目前的理论理解不一致。 为了为更好地利用超导性和超流性铺平道路，非常重要的是在3He中获得这种理解，使用通过非常多孔的二氧化硅气凝胶以受控的方式引入到3He中的杂质。 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竞赛准备项目。 教师，博士后和研究生的监督与这些项目的整合是一个独特的和互利的经验。拟议的研究将发展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。 本课程包括超导材料，其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，使用类似于光学技术的技术，这些技术在过去50年中在超导材料领域非常重要。 建议的研究将提高序参数集体模式的频谱在超流3He的几个数量级使用新的声学原理。 这些实验将揭示超流体的性质和物理机制。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，拟议的工作将对它们的应用产生广泛的影响。 第二个目标是确定超导和超流行为对杂质的敏感性。 这些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。 两名当地高中生计划根据他们在大学实验室的经验为全国英特尔竞赛准备项目。 教师，博士后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的和互利的经验。