CAREER: Fundamental phenomena in magnon condensates

非技术摘要：玻色子是允许玻色-爱因斯坦凝聚（BEC）基本量子效应的整数自旋粒子，它表现为在非相干多粒子系统中自发形成宏观相干量子态。该项目将提高对磁性准粒子-磁振子中的BEC现象的理解。这项工作可能会对量子信息科学、固态物理和现代磁学领域产生变革性影响，并有助于保持美国在量子信息科学和技术领域的领导地位。这个CAREER项目利用最先进的纳米制造、光学和微波表征技术，探索铁磁结构，以了解磁振子BEC特性以及与高密度磁振子气体的相互作用。该项目的教育部分将当代研究主题整合到现有的研究生和本科课程中，创建新的量子物理和量子信息科学实验课程，为广泛的社区提供科学发展的途径，并通过组织科学比赛增加STEM学生的数量。技术摘要：尽管在磁振子气体和凝析物领域取得了许多成就，如磁振子超流、波高留博夫波、约瑟夫森效应和第二声的观测，但仍有许多有趣的基本问题尚未解决。其中之一是这些现象如何受到边界或几何约束的影响，以及在铁磁材料中支持磁振子BEC的系统的临界尺寸是什么。该项目将最先进的微纳米结构与光学布里渊光散射光谱相结合，并引入室温和低温下的光学加热技术。该项目的目标是：(i)实验观察和比较传统三维、准二维和准一维结构中的磁振子BEC动力学；建立一个持久的精简阶段，并确定其存在的领域；（ii）具有周期边界条件（环）系统中磁振子BEC的性质研究；（iii）在连续和受限样品中建立完整的磁振子秒声和波高留波联合模型；（四）实验观察和研究磁振子热力学激光效应。该项目支持本科生和研究生在先进光谱学技术、低温学和纳米制造方面的培训。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical abstract:Bosons are particles of integer spin that allow for the fundamental quantum effect of Bose-Einstein Condensation (BEC), which manifests as the spontaneous formation of a macroscopic coherent quantum state in an otherwise incoherent multi-particle system. The project will improve understanding of the BEC phenomenon in magnetic quasiparticles – magnons. This work may have a transformative effect on the fields of quantum information science, solid-state physics, and modern magnetism, as well as help maintain US leadership in the area of quantum information science and technology. This CAREER project explores ferromagnetic structures to understand magnon BEC properties and interactions with a dense magnon gas existing alongside it using state-of-the-art nanofabrication, optical, and microwave characterization techniques. The educational component of the project integrates contemporary research themes into existing graduate and undergraduate courses, creates new quantum physics and quantum information science lab courses, provides access to scientific developments to a broad community, and increases the number of students in STEM through the organization of scientific tournaments.Technical abstract:Despite many achievements in the field of magnon gases and condensates, like the observation of magnon supercurrents, Bogoliubov waves, Josephson effect, and second sound, there are many intriguing fundamental questions still open. One of them is how these phenomena are affected by boundaries or geometrical confinement, and what are the critical sizes of the system to support magnon BEC in ferromagnetic materials. The project combines state-of-the-art micro- and nano-structuring with optical Brillouin light scattering spectroscopy and introduces optical heating techniques at room as well as cryogenic temperatures. The project's aims are: (i) Experimentally observe and compare magnon BEC dynamics in conventional 3D, quasi-2D, and quasi-1D structures; (ii) Create a persistent condensed phase and determine its areas of existence; (ii) Study properties of magnon BEC in systems with periodic boundary conditions (rings); (iii) Create a complete joint model of magnon second sound and Bogoliubov waves in continuous and confined samples; (iv) Experimental observe and study magnon thermodynamic lasing effect. The project supports the training of undergraduate and graduate students in advanced optical spectroscopy techniques, cryogenics, and nanofabrication.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.