Coherent Diffraction Imaging with Superfluid He Nano-Droplets

液氦中的超流性吸引了凝聚态物理学家们一个世纪，直到今天仍然是一个非常有趣的话题。这种行为是宏观量子效应的一个例子，类似于某些材料中发生的超导行为。 在液氦中，这种宏观量子行为以许多迷人的方式表现出来，其中之一是正常液体所表现出的粘性消失。 这导致了许多有趣的现象，例如长寿命量子涡旋线的出现。 本计划将利用直线加速器相干光源上新开发的X射线自由电子激光器来探索悬浮氦滴的流体动力学。 这项研究将产生的新见解将有助于我们理解涡旋对从超导体到中子星等系统的影响。 此外，该项目将开发的工具，将是非常有益的材料科学家开发新的nanomaterials.Technical Abstract本项目将探索量子旋转4-He液滴带来新的物理见解量子流体力学在介观尺度。特别地，本研究将：（i）有助于在可用的角动量-角速度相空间中描述旋转量子液滴，并确定旋转超流和经典液滴是否属于相同的形状族;（ii）提供涡旋的固定形状和配置。（N = 1-200）的涡团，这些涡团在理论上和实验上都没有得到研究：（iii）通过研究涡团簇的修饰，揭示涡团质量对涡团动力学的影响;和（iv）阐明量子旋转在极端的涡度，高达约100000的因素，高于在散装实验中获得的，提供访问未开发的制度，在量子液体中的旋转激发。在直线加速器相干光源自由电子激光器处的单次发射飞秒X射线相干衍射成像与新的图像重建算法耦合将用于重建液滴形状和液滴内涡旋位置的真实的空间图像。

Non-technical AbstractSuperfluidity in liquid helium has fascinated condensed matter physicists for a century and remains a topic of great interest even today. This behavior is an example of a macroscopic quantum effect similar to the superconducting behavior that occurs in some materials. In liquid helium this macroscopic quantum behavior manifests itself in many fascinating ways one of which is the disappearance of the viscosity exhibited by normal liquids. This leads to many interesting phenomena such as the appearance of long lived quantum vortex lines. This project will make use of the newly developed x-ray free electron laser at the Linac Coherent Light Source to explore the hydrodynamics of feely suspended helium droplets. The new insights this research will produce will help in our understanding of the effects of vortices on systems ranging from superconductors to neutron stars. In addition, the tools that will be developed during this project will be of great benefit to materials scientists developing new nanomaterials.Technical AbstractThis project will explore quantum rotation in 4-He droplets to bring new physical insights into quantum hydrodynamics at the meso-scale. In particular, this study will: (i) contribute to the description of rotating quantum droplets across the available angular momentum - angular velocity phase space and determine if the rotating superfluid and classical droplets belong to the same families of shapes; (ii) provide stationary shapes and configurations of vortices (N = 1-200) in a droplet, which remain unstudied experimentally or theoretically; (iii) reveal the effect of vortex mass on their dynamics by studying vortices decorated with Xe clusters; and (iv) elucidate quantum rotation at extreme vorticity, up to a factor of about 100000 higher than attained in bulk experiments, providing access to unexplored regimes of rotational excitation in quantum liquids. Single-shot femtosecond X-ray coherent diffractive imaging at the Linac Coherent Light Source free electron laser coupled with new image reconstruction algorithms will be used to reconstruct real space images of the shape of the droplets and the location of vortices within the droplet.