Renewal: Fundamental Physics of Polariton Condensates

更新：极化子凝聚体的基础物理

• 批准号: 2306977
• 负责人: David Snoke
• 金额: $ 75.83万
• 依托单位: University of Pittsburgh
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2306977&HistoricalAwards=false
• 关键词: Renewal; Fundamental; Physics; Polariton; Condensates

Nontechnical decription:This project, funded jointly by the Condensed Matter Physics and Atomic, Molecular and Optical Physics - Experiment programs, supports fundamental physics studies in a new class of superfluids. Superfluidity is an intrinsically quantum phenomenon in which below a certain temperature, many particles spontaneously join together to act as a wave. There are just a few physical systems that are known to act this way. The oldest is superfluid liquid helium, which flows with zero viscosity. Superconducting metals are another example, in which electrons act as a wave, and flow with zero resistance, and ultracold atoms in ultrahigh vacuum, stabilized by laser beams and magnetic field are another. In the past decade, another class of superfluid has received widespread attention, namely “heavy photons” known as “polaritons,” in which photons can flow like a liquid. This project supports basic research studies of these polariton superfluids, made possible by using semiconductor structures, fabricated as part of this project, that are the best in the world in terms of smoothness and lack of impurities. This project can have broad impact in increasing our understanding of universal properties of superfluids, and in making possible new types of optical communications devices. The PI of the project will also continue to collaborate with the Carnegie Science Center in Pittsburgh to educate the public on general quantum mechanics and optics topics.Technical description: This project supports the continuing work of PI Snoke on fundamental properties of exciton-polaritons in GaAs-AlGaAs microcavities. The structures are designed by the Snoke group and then fabricated using molecular-beam epitaxy by two labs, the group of Loren Pfeiffer at Princeton and the group of Zbig Wasilewski at the University of Waterloo. One goal of the project is to advance the quality of these microcavity structures, in particular to make large area structures with a high degree of flatness and very little leakage of light out of the structures, which will allow the possibility of optical circuits on a chip with propagation lengths of hundreds of microns. The Snoke group will use advanced optical methods including picosecond time-resolved spectroscopy, imaging, and interferometry to study polariton superfluids in these structures. In the past year, two breakthrough results have been obtained, and an immediate goal will be to perform followup experiments to fully understand these effects. One of these is the demonstration of a true persistent current of a polariton superfluid in a ring. While indirect evidence for persistent current has been seen in other systems, the microcavity polariton system allows direct, in situ measurement of the phase of the superfluid while it is circulating. The other new result is a highly accurate measurement of the superfluid fraction while the system is in thermal equilibrium. A universal power law has been observed which was not theoretically predicted nor observed in other experimental systems. Ongoing collaboration with many-body theorists will seek to create an analytical model for this power law. In the longer term, this project will seek to make networks of coupled polariton superfluids, which can be used both for ultrafast (~10 ps) optical switching methods as well as novel methods of analog optical computing to solve mathematical problems that are hard for traditional computers.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.

非技术描述：该项目是由凝聚态物理学和原子，分子和光学物理学共同基本的 - 实验计划，支持新的超级流体类别中的基本物理研究。超流体是一种本质上的量子现象，在该现象中，许多颗粒在一定温度以下，许多颗粒都将其融合在一起以充当波。有几个物理系统以这种方式行事。最古老的是超流体液态氦，其粘度为零。超导金属是另一个例子，其中电子充当波，并且具有零电阻的流动，而超高原子在超高真空中被激光束和磁场稳定。在过去的十年中，另一类超级流体引起了人们的关注，即“重型照片”称为“ polaritons”，其中照片可以像液体一样流动。该项目支持对这些极化超流体的基础研究，该研究通过使用作为该项目的一部分而制造的半导体结构，这是世界上最好的，这是世界上最好的，而在平稳性和缺乏杂质方面。该项目可能会对我们对超流体的通用性质的理解以及使新型的光学通信设备的新类型产生广泛的影响。该项目的PI还将继续与匹兹堡的卡内基科学中心合作，向公众提供有关通用量子力学和光学主题的教育。技术描述：该项目支持Pi Snoke在Gaas-Algaas MicroCavities中持续的Pi Snoke关于令人兴奋的极乐人的基本属性。这些结构是由Snoke组设计的，然后由两个实验室，Princeton的Loren Pfeiffer组和Waterloo大学的Zbig Wasilewski组制成。该项目的一个目标是提高这些微腔内结构的质量，特别是使具有高度平坦的大面积结构，光线很少从结构中泄漏，这将使在芯片上具有传播长度的芯片上的光电可能性。 Snoke组将使用先进的光学方法，包括皮秒时间分辨光谱，成像和干扰来研究这些结构中的极性超流体。在过去的一年中，已经获得了两个突破性的结果，直接目标是执行后续实验以充分了解这些影响。其中之一是表明环中极地超流体的真实持续电流的演示。尽管在其他系统中已经看到了持续电流的间接证据，但微腔极化系统允许直接测量超级流体循环时的相位。另一个新的结果是在系统处于热平衡状态时对超流体分数进行了高度准确的测量。已经观察到了一种普遍的力量定律，在其他实验系统中没有从理论上预测或观察到。与多体理论家进行的持续合作将寻求为该权力法创建一个分析模型。从长远来看，该项目将寻求建立耦合的极性超流体网络，可用于超快（〜10 ps）的光学切换方法以及类似光学计算的新方法来解决数学问题，这些问题难以解决传统计算机的难度。这些奖项反映了NSF的法定委员和众多的依据，这是通过评估良好的构成的依据。