Collaborative Research: Stanford-Florida program in Support of LIGO on Coatings and Core Optics

合作研究：斯坦福大学-佛罗里达州支持 LIGO 涂层和核心光学器件的项目

• 批准号: 2011776
• 负责人: Hai-Ping Cheng
• 金额: $ 24万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011776&HistoricalAwards=false
• 关键词: Collaborative; Research; Stanford; Florida; program

This award supports research in relativity and relativistic astrophysics and it addresses the priority areas of NSF's "Windows on the Universe" Big Idea. The detection of gravitational waves from coalescing black holes in 2015 launched the field of gravitational wave astronomy. Gravitational-wave detectors with a two-fold increase in sensitivity over Advanced LIGO would yield an order of magnitude increase in detection rate for black hole coalescences, and enable detection of fainter objects like binary neutron stars, greatly increasing their value for multi-messenger astronomy. All future detector upgrades and concepts rely on the development of new mirror coating materials to reduce thermal noise, which is the core research focus this collaborative project between Martin Fejer's group at Stanford University and Hai-Ping Cheng's group at the University of Florida. Reducing this noise source requires reducing the mechanical loss in the mirror coatings on the test masses. The goal of this project is to develop mirror coatings consistent with the mechanical and optical requirements for implementation in future generations of LIGO. Meeting this goal for room temperature detectors requires a solution of a longstanding problem in the physics of amorphous materials: understanding the nature of and finding means to reduce the low-energy excitations in amorphous metal oxides. On a longer time-scale, the proposed 3G detectors' cryogenic operation broadens the possible choice of low-noise mirror materials to include amorphous or crystalline semiconductors.The mid-band sensitivity of the Advanced LIGO detectors is limited by thermal noise resulting from mechanical loss in the mirror coatings, and future upgrades including Advanced LIGO Plus will seek to reduce this source of noise by a factor of two or more. The Stanford-Florida partnership, alongside collaborators in the LSC Center for Coatings Research (CCR), has identified different structural motifs associated with room-temperature vs cryogenic mechanical losses, which led to synthesis of germania (GeO2) films, giving rise to the lowest-loss amorphous oxide film other than silica. Going forward, this structural guide, based on electron and x-ray scattering atomic structure data, will serve as a paradigm informing the development of high-refractive-index amorphous coatings with lower elastic loss. Atomic modeling of coating elastic loss combined with simulations of the coating deposition process will provide guidance for the selection of candidate materials, assist in interpretation of experimental structure data, and will ultimately assist in the design of synthesis experiments. Another long-standing effort at Stanford has been measurements of the absorption of low-optical-loss materials at the sub-ppm/cm level, dating back to the down select between silica and sapphire for initial LIGO test masses. The groups will continue to use the interferometric tool developed for those studies to characterize cryogenic losses in single-crystal silicon samples to evaluate their suitability for implementation in the Voyager technology demonstrator and future cryogenic detectors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项支持相对论和相对论天体物理学的研究，并涉及美国国家科学基金会“宇宙之窗”大创意的优先领域。 2015年对聚结黑洞的引力波的探测开启了引力波天文学领域。引力波探测器的灵敏度比高级 LIGO 提高两倍，黑洞聚结的探测率将提高一个数量级，并能够探测到双中子星等较暗的物体，从而大大提高其在多信使天文学中的价值。未来所有探测器的升级和概念都依赖于开发新型镜面涂层材料来降低热噪声，这是斯坦福大学 Martin Fejer 团队和佛罗里达大学 Hai-Ping Cheng 团队合作项目的核心研究重点。减少这种噪声源需要减少测试质量上镜面涂层的机械损耗。该项目的目标是开发符合未来几代 LIGO 实施的机械和光学要求的镜面涂层。要实现室温探测器的这一目标，需要解决非晶材料物理学中长期存在的问题：了解非晶金属氧化物的性质并找到减少非晶金属氧化物中低能激发的方法。在更长的时间尺度上，拟议的 3G 探测器的低温操作拓宽了低噪声反射镜材料的可能选择，包括非晶或晶体半导体。高级 LIGO 探测器的中频灵敏度受到反射镜涂层机械损耗产生的热噪声的限制，包括高级 LIGO Plus 在内的未来升级将寻求将这种噪声源减少两倍或更多。斯坦福大学与佛罗里达州的合作伙伴关系以及 LSC 涂料研究中心 (CCR) 的合作者已经确定了与室温和低温机械损失相关的不同结构基序，从而合成了氧化锗 (GeO2) 薄膜，从而形成了除二氧化硅之外损失最低的无定形氧化物薄膜。展望未来，这种基于电子和 X 射线散射原子结构数据的结构指南将成为开发具有较低弹性损失的高折射率非晶涂层的范例。涂层弹性损失的原子建模与涂层沉积过程的模拟相结合将为候选材料的选择提供指导，协助解释实验结构数据，并最终协助合成实验的设计。斯坦福大学的另一项长期工作是测量亚 ppm/cm 水平的低光损耗材料的吸收率，这可以追溯到最初 LIGO 测试质量中二氧化硅和蓝宝石之间的选择。这些小组将继续使用为这些研究开发的干涉测量工具来表征单晶硅样品中的低温损失，以评估其在 Voyager 技术演示器和未来低温探测器中实施的适用性。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Annealing‐Induced Changes in the Atomic Structure of Amorphous Silica, Germania, and Tantala Using Accelerated Molecular Dynamics

退火——利用加速分子动力学引起无定形二氧化硅、二氧化锗和钽原子结构的变化

• DOI: 10.1002/pssb.202000519
• 发表时间: 2021
• 期刊: physica status solidi (b
• 作者: Prasai, Kiran;Bassiri, Riccardo;Cheng, Hai-Ping;Fejer, Martin M.
• 通讯作者: Fejer, Martin M.

Hidden structure in the medium-range order of amorphous zirconia-tantala films

非晶氧化锆-钽薄膜的中程隐藏结构

• DOI: 10.1103/physrevb.108.054103
• 发表时间: 2023
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Mishkin, Alec;Jiang, Jun;Zhang, Rui;Cheng, Hai-Ping;Prasai, Kiran;Bassiri, Riccardo;Fejer, Martin
• 通讯作者: Fejer, Martin

Amorphous Zirconia-doped Tantala modeling and simulations using explicit multi-element spectral neighbor analysis machine learning potentials (EME-SNAP)

使用显式多元素光谱邻域分析机器学习潜力 (EME-SNAP) 对非晶氧化锆掺杂 Tantala 进行建模和模拟

• DOI: 10.1103/physrevmaterials.7.045602
• 发表时间: 2023
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: Jiang, Jun;Li, Xiang-Guo;Mishkin, Alec S.;Zhang, Rui;Bassiri, Riccardo;Fry, James N.;Fejer, Martin M.;Cheng, Hai-Ping
• 通讯作者: Cheng, Hai-Ping