Third Sound Study of Pinned Vortices

9322389埃利斯技术摘要：第三个声波将用于研究低温下超流4He薄膜中的涡旋特性。这些涡旋最近被证明存在于远低于超流体转变的地方，被固定在衬底上，并在适度的薄膜流动下保持稳定。大幅度的第三声波不仅提供足够大的薄膜流动来移动漩涡，而且能够通过旋涡的量子力学类比来创造和摧毁漩涡。采用小波幅波法探测涡流分布。这项对涡旋钉扎和产生的详细研究将有助于更好地理解低温下天然涡旋的重要性及其性质。非技术摘要：这项研究将研究超流氦薄膜中微观量子循环态的性质。这些涡旋已被证明在超流体转变温度附近对薄膜的性质起作用，并将首次通过它们与声波的相互作用在较低温度下直接研究。与其对应的超导电性不同，在超流状态的微观描述中仍然存在一些基本问题，澄清薄膜中涡旋的作用将有助于对凝聚态物理的总体理解。***

9322389 Ellis Technical abstract: Third sound waves will be used to study the properties of vortices in superfluid 4He films at low temperatures. These vortices have been recently shown to exist well below the superfluid transition, pinned to the substrate and stable against moderate film flow. Large amplitude third sound waves not only provide film flow large enough to move the vortices, but are able to create and destroy the vortices by the quantum-mechanical analogy of swirling. Small amplitude waves are used to probe the vortex distribution. This detailed study of vortex pinning and creation will provide better understanding of the importance of innate vortices at low temperatures and their properties. Non-technical abstract: This research will investigate the properties of microscopic quantized circulation states in thin films of superfluid helium. These vortices have been shown to play a role in the properties of films near the superfluid transition temperature and will be studied directly for the first time at lower temperatures by their interaction with sound waves. Unlike its counterpart superconductivity, there remain fundamental problems in the microscopic description of the superfluid state and clarifying the role of the vortices in films will contribute to the general understanding of condensed matter physics. ***