CAREER: Nature of Pure and Dirty Liquid 3He-Fundamental Investigations and Educational Activities

这个低温物理职业项目将使用超声光谱技术研究纯净和肮脏的超流体3 He的基本性质。 强磁场（高达15 T）的脏p波超流体中存在的磁性和非磁性杂质的影响将进行研究。 这项工作将提供重要的信息，这个相对较新的系统的相图，并有可能揭示新的现象附近的临界压力。 临界压力与量子相变有关，这在一系列凝聚态系统中引起了极大的兴趣。 使用横向声光谱技术，直接证据的次主导f波配对相互作用的B相将进行调查。 这种新的光谱技术被认为是上级在寻找新的集体模式，其存在是唯一的f-波配对相互作用的传统技术。 新模式的观测将是第一次实验证实集体模式产生的次主导配对相互作用在更一般的一类超流体。 将使用零声来研究转捩以上的波动效应。 已知的背景贡献和极高的分辨率在零声速测量将有助于直接测量的相干长度。 这个低温物理职业项目将使用超声光谱技术研究纯的和所谓的脏超流体3 He的基本特性。脏超流体是指存在非常低密度多孔固体（如气凝胶）的超流体样品。 这项研究在接近绝对零度的温度下进行，不仅与研究3 He和4 He性质的科学家量子流体社区有关，而且与凝聚态物理学的许多其他领域有关。 近年来，人们在各种凝聚态系统中发现了许多与量子相变有关的有趣现象，并对其进行了广泛的研究。 与发生在有限温度（如固体熔化）的传统（经典）相变不同，量子相变是从纯粹的量子力学起源触发的，因此可以发生在绝对零度。 脏超流系统是研究这种量子相变的一个很好的系统，特别是在临界压力附近。 研究了强磁场对无序超流3 He相图的影响。 在其他的工作中，详细的微观起源的超流在纯超流3 He将通过一个新的激发态的库珀对（3 He原子）使用一种新的横向声光谱技术的搜索。将通过进行高分辨率声速测量来研究高于但接近转变温度的初始超流性。 超流性的产生是由短寿命的库珀对的热驱动涨落引起的。 该研究涉及研究生和本科生的广泛参与，他们将获得广泛的严格的实验室经验和培训，以便在企业，工业或政府中获得以后的职业机会。该研究项目包括一个重要的组成部分，旨在改善当地高中科学教育。

This low temperature physics CAREER project will investigate the fundamental nature of pure and dirty superfluid 3He using ultrasound spectroscopic techniques. The effect of strong magnetic fields (up to 15 T) on the dirty p-wave superfluid in the presence of magnetic and non-magnetic impurities will be investigated. This work will provide important information on the phase diagram of this relatively new system and has the potential to reveal new phenomena near the critical pressure. The critical pressure is related to quantum phase transitions, which are of great current interest in a range of condensed matter systems. Using a transverse sound spectroscopic technique, direct evidence of a sub-dominant f-wave pairing interaction in the B-phase will be investigated. This novel spectroscopic technique is believed to be superior to the conventional technique in searching for the new collective modes whose existence is guaranteed only by the f-wave pairing interaction. The observation of the new mode would be the first experimental confirmation of the collective modes generated by the subdominant pairing interaction in a more general class of superfluids. Fluctuation effects above the transition will be studied using zero sound. The known background contribution and an extremely high resolution in the zero sound velocity measurements will facilitate the direct measurement of the coherence length. This low temperature physics CAREER project will investigate fundamental properties of pure and so-called dirty superfluid 3He using ultrasound spectroscopic techniques. Dirty superfluid refers to superfluid samples in the presence of very low-density porous solids, such as an aerogel. The research, near the absolute zero of temperature, is relevant not only to the quantum fluids community, scientists who investigate the properties of 3He and 4He, but to many other areas of condensed matter physics. Recently, many interesting phenomena related to quantum phase transitions have been discovered and studied extensively in various condensed matter systems. Unlike conventional (classical) transitions, which occur at finite temperatures such as melting of solids, quantum phase transitions are triggered from purely quantum mechanical origins and accordingly can occur at absolute zero temperature. The dirty superfluid system is an excellent system to study this quantum phase transitions especially near the critical pressure. The effect of strong magnetic fields on the phase diagram of disordered superfluid 3He will be investigated. In other work, the detailed microscopic origin of superfluidity in pure superfluid 3He will be investigated via a search for a new excited state of the Cooper pairs (of 3He atoms) using a novel transverse sound spectroscopic technique. The incipient superfluidity above, but near, the transition temperature will be studied by conducting high resolution sound velocity measurements. The incipient superfluidity is caused by the thermally driven fluctuations of Cooper pairs with a short lifetime. The research involves extensive participation of both graduate and undergraduate students, who will be provided a wide range of rigorous laboratory experience and training for later career opportunities in academe, industry or government. The research project includes an important integral component directed toward improving local high school science education.