Interrogation and Manipulation of Coherences in Superfluid Helium

超流氦中相干性的询问和操纵

• 批准号: 0317138
• 负责人: Vartkess Apkarian
• 金额: $ 34.2万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-15 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0317138&HistoricalAwards=false
• 关键词: Interrogation; Manipulation; Coherences; Superfluid; Helium

In this project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Apkarian will conduct an experimental research program aimed at fundamental studies of bulk superfluid helium (He-II). The general goals are to investigate microscopic implications of the system, principally its quantum collective dynamics in order to manipulate coherences through multilinear spectroscopy. Superfluid helium streams were recently developed as the carrier fluid in a universal molecule injector, but their properties are not yet sufficiently understood. The properties of the neat stream, namely of a suddenly expanded Bose condensate, are of fundamental and practical interest. The streams will be characterized as a function of the pulsed expansion conditions, such as reservoir temperature, pressure, pulse length, and nozzle design. Light scattering will be used to characterize transitions from droplet to continuous flow; interferometric imaging will be used to quantify density and divergence of the stream; and second harmonic generation will be use to characterize ordered vorticity. Molecular impurities entrained in the stream will be studied spectroscopically. Among additional studies there will be investigations of stream-embedded hydrogen molecules by means of time/frequency resolved CARS spectroscopy, and the coherent rotations of hydrogen will be used to investigate the size dependent liquid-solid transition of hydrogen clusters and the possible superfluidity of these clusters. Graduate and undergraduate students as well as postdoctorate researchers will gain valuable experience through participation in this research, which involves cryogenic engineering, optical engineering, and modern laser techniques, as well as the use of techniques involved in molecular manipulations at 1 K. Nearly all core areas of the sciences, both classical and quantum mechanical, will be used in this research, with the result that the participants will have an unusually rich learning and training experience.

在这个由化学部实验物理化学计划资助的项目中，Apkarian将进行一项旨在对散装超流氦（He-II）进行基础研究的实验研究计划。 总体目标是研究系统的微观含义，主要是其量子集体动力学，以便通过多线性光谱操纵相干性。 超流氦流是近年来发展起来的一种通用分子注入器的载流，但其性质尚不清楚。 纯流的性质，即突然膨胀的玻色凝聚，是基本的和实际的兴趣。 这些流将被表征为脉冲膨胀条件的函数，例如储层温度、压力、脉冲长度和喷嘴设计。 光散射将用于表征从液滴到连续流的过渡;干涉成像将用于量化流的密度和发散;二次谐波产生将用于表征有序涡度。 将用光谱法研究气流中夹带的分子杂质。 在额外的研究中，将通过时间/频率分辨汽车光谱对嵌入流的氢分子进行调查，氢的相干旋转将用于调查氢团簇的尺寸相关的液-固转变以及这些团簇可能的超流性。 研究生和本科生以及博士后研究人员将通过参与这项研究获得宝贵的经验，该研究涉及低温工程，光学工程和现代激光技术，以及在1 K下使用分子操纵技术。 几乎所有的科学核心领域，包括经典和量子力学，都将用于这项研究，因此参与者将拥有异常丰富的学习和培训经验。