Superfluid Macroscopic Quantum Effects

* 非技术摘要 * 超流氦是一种奇异的物质状态，其中正常大小的液体样品表现出原子量子世界的一些奇怪特征。这个个人研究者奖支持一个专注于所谓的约瑟夫森效应的项目。超流氦被推动通过在薄隔板上钻的数千个纳米大小的孔阵列。与普通流体以与推力成比例的速率简单地流过孔不同，超流体在孔内来回移动，平均而言，没有液体通过孔。推得越用力，振动发生得越快。如果孔小于特征长度，基本理论解释了为什么这种振荡流应该发生在单个孔中。然而，它仍然是一个谜，为什么这种振荡流发生在所有的孔在一个阵列同步。这也是一个谜，为什么振动甚至发生在比理论预测的更大的孔的尺寸。该项目的核心目标是解决这些谜团，并进一步利用这些现象来创建一种新的超灵敏仪器，这些仪器将在物理学，地球研究和导航中有用。该项目不仅将培养研究生和博士后研究人员在科学前沿的想法，但在仪器和纳米制造的技能，他们将学习进行实验是在工业和学术界的巨大需求。技术摘要 * 被限制在数千个纳米孔的阵列内的超流氦表现出各种约瑟夫森现象，包括正弦状电流-相位关系以及在约瑟夫森频率下发生的同步耗散相位滑移。这些特征已被利用来显示由旋转和热诱导流动引起的宏观量子干涉效应。这个个人研究项目的中心目标是双重的：1。理解跨阵列的同步性的起源和2.以确定如何使阵列的特性最适合用于量子干涉仪，专门用于旋转传感和探测新的物理相互作用。最初，将采用经验方法来确定具有各种孔径尺寸和图案的阵列的特性。这些结果将与理论进行比较。最终将开发出灵敏的超流干涉仪，以探测奇异的物理效应，如中性物质中的Aharonov-Bohm相移。沿着科学前沿的知识，博士生和博士后研究人员将学习纳米纤维，低温，电子仪器和计算机控制技术。

****NON-TECHNICAL ABSTRACT****Superfluiid helium is an exotic state of matter wherein normal sized samples of liquid exhibit some of the strange features of the quantum world of atoms. This individual investigator award supports a project focusing on the so-called Josephson effects. Superfluid helium is pushed through an array of thousands of nanometer-sized holes drilled in a thin partition. Unlike ordinary fluids that would simply flow through the holes at a rate proportional to the pushing force, the superfluid moves to and fro within the holes with, on the average, no liquid passing through the holes. The harder one pushes, the faster the vibrations occur. If the apertures are smaller than a characteristic length, basic theory explains why this oscillatory flow should occur in a single aperture. However, it remains a mystery why this oscillatory flow occurs in all the apertures in an array synchronously. It is also a mystery why the vibrations occur even for hole sizes bigger than those predicted by theory. The central goal of the project is to solve these mysteries and further, to exploit the phenomena to create a new class of ultra-sensitive instruments that will be useful in physics, earth studies and navigation. Not only will this project train graduate students and postdoctoral researchers in ideas at the forefront of science, but the skills in instrumentation and nano-fabrication that they will learn to carry out the experiments are in great demand in industry and academia.****TECHNICAL ABSTRACT****Superfluid Helium constrained within an array of thousands of nano-apertures exhibits a variety of Josephson phenomena including a sine-like current-phase relation as well as synchronous dissipative phase slippage, occurring at the Josephson frequency. These features have been exploited to show macroscopic quantum interference effects induced by rotation and heat induced flow. The central goals of this individual investigator project are twofold: 1. to understand the origin of the synchronicity across an array and 2. to determine how to make arrays with characteristics most suitable for use in quantum interferometers devoted to rotation sensing and probing novel physical interactions. Initially an empirical approach will be pursued to determine the characteristics of arrays with various aperture sizes and patterns. These results will be compared to theory. Ultimately sensitive superfluid interferometers to probe exotic physical effects such as an Aharonov-Bohm phase shift in neutral matter will be developed. Along with knowledge at the frontiers of science, PhD students and postdoctoral researchers will learn techniques of nanofabrication, cryogenics, electronic instrumentation and computer control.