Superfluid Macroscopic Quantum Effects

****非技术摘要****超流氦是一种奇特的物质状态，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约瑟夫森效应的项目。超流氦通过在薄隔板上钻出的数千个纳米大小的孔。普通流体只会以与推力成正比的速率流过孔洞，而超流体在孔洞内来回移动，平均而言，没有液体通过孔洞。推得越用力，振动就发生得越快。如果孔径小于特征长度，基本理论解释了为什么振荡流会发生在单个孔径中。然而，为什么这种振荡流同时发生在阵列的所有孔中，这仍然是一个谜。这也是一个谜，为什么即使是比理论预测的更大的洞也会发生振动。该项目的中心目标是解开这些谜团，并进一步利用这些现象来创造一种新型的超灵敏仪器，这种仪器将在物理学、地球研究和导航领域发挥作用。这个项目不仅将培养研究生和博士后研究人员在科学前沿的思想，而且他们将学习进行实验的仪器和纳米制造技能，这在工业界和学术界都是非常需要的。****技术摘要****超流氦被限制在数千个纳米孔径阵列中，表现出多种约瑟夫森现象，包括正弦电流相关系以及同步耗散相滑移，发生在约瑟夫森频率下。这些特征已经被用来展示由旋转和热流引起的宏观量子干涉效应。这个个人研究者项目的中心目标是双重的：1。要了解跨数组和2的同步性的起源。确定如何使阵列具有最适合用于量子干涉仪的特性，用于旋转传感和探测新的物理相互作用。首先将采用经验方法来确定具有不同孔径大小和模式的阵列的特性。这些结果将与理论进行比较。最终，灵敏的超流体干涉仪将用于探测奇异的物理效应，如中性物质中的Aharonov-Bohm相移。除了科学前沿的知识，博士生和博士后研究人员还将学习纳米制造、低温学、电子仪器和计算机控制等技术。

****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.