CAREER: Probing exciton-exciton correlations and phase transitions for spin-polarized excitons in monolayer transition metal dichalcogenides

职业：探索单层过渡金属二硫化物中自旋极化激子的激子-激子相关性和相变

• 批准号: 2142703
• 负责人: Xiao-Xiao Zhang
• 金额: $ 77.92万
• 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: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2142703&HistoricalAwards=false
• 关键词: CAREER; Probing; exciton; correlations; phase

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Non-technical abstract When light is absorbed by a solid, it can create a transient excitation quasiparticle, the so-called exciton, which carries information from both the light and the matter. Understanding excitonic interactions are crucial for the future design of quantum devices with contact-free, all-optical control and sensing. This project investigates the quantum correlations between excitons in an atomically-thin two-dimensional crystal with exceptionally strong light-matter interactions. The unique optical and electronic properties of the two-dimensional crystal promise the realization of quantum correlation well above the liquid helium temperature. The research results will establish new platform systems to achieve on-chip operation and control of coherence for future quantum technology developments. Integrated with the research, the project aims to promote the participation of women in STEM and train the next-generation STEM workforce through interdisciplinary research projects and tasks. A series of career support seminars for women in STEM will be organized at the University of Florida. In addition, optics science demonstration stations will be developed for display in a local museum to increase STEM awareness in a younger generation.This project is jointly funded by the Condensed Matter Physics (CMP) and the Electronic and Photonic Materials (EPM) programs of the Division of Materials Research (DMR).Technical abstract An exciton is a bound electron-hole pair that can be considered as a Boson, often created through optical excitations in semiconductors. Beyond the dilute exciton gas limit, exciton-exciton correlation forms, and the possibility of achieving quantum degeneracy of exciton liquid and condensate phases have attracted great attention for decades. The recent advent of two-dimensional (2D) semiconductors of transition metal dichalcogenides provides a completely new paradigm for exciton physics, where excitons have anomalously strong binding energy and enable all-optical control of the spin and valley degrees of freedom. This project aims to investigate the nonlinear exciton interactions and seek experimental signatures of exciton complex correlations in tungsten-based monolayer transition metal dichalcogenides. In particular, this research will focus on spin-polarized excitonic states, which have long lifetimes and support a high exciton density. Both the classical regime and the possible quantum degeneracy of 2D excitons will be investigated through a combination of ultrafast optical spectroscopies and optoelectronic probes. The outcome will inform our understanding of excitonic many-body interactions in 2D and lay the foundation for realizing macroscopic coherence in compact 2D devices. Investigation of these spin-polarized excitons will also elucidate how the spin polarization of bosons affects the formation of correlation and further macroscopic coherence.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.

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。非技术摘要当光被固体吸收时，它可以产生一种瞬时激发的准粒子，即所谓的激子，它携带着来自光和物质的信息。了解激子相互作用对于未来设计具有非接触、全光学控制和传感的量子设备至关重要。这个项目研究了原子薄的二维晶体中激子之间的量子关联，这种晶体具有非常强的光-物质相互作用。这种二维晶体具有独特的光学和电学性质，有望在液氦温度以上实现量子关联。研究成果将为未来的量子技术发展建立新的平台系统，实现芯片上的操作和相干控制。该项目与研究相结合，旨在促进妇女参与STEM，并通过跨学科研究项目和任务培训下一代STEM劳动力。将在佛罗里达大学为STEM中的妇女举办一系列职业支持研讨会。此外，光学科学示范站将在当地一家博物馆展出，以提高年轻一代对STEM的认识。该项目由材料研究部(DMR)的凝聚态物质物理(CMP)和电子与光子材料(EPM)计划联合资助。技术摘要激子是可被视为玻色子的束缚电子-空穴对，通常通过半导体中的光激发产生。激子-激子关联在稀薄激子气体极限以上形成，激子液体和凝聚相实现量子简并的可能性几十年来一直引起人们的极大关注。最近过渡金属二卤化物的二维半导体的出现为激子物理提供了一种全新的范式，其中激子具有反常的强结合能，并能够实现对自旋和山谷自由度的全光学控制。本项目旨在研究钨基单分子层过渡金属二卤化物中的非线性激子相互作用，并寻找激子络合物关联的实验特征。特别是，这项研究将集中在自旋极化激子态，它具有长寿命和支持高激子密度。我们将结合超快光学光谱和光电探针来研究二维激子的经典区域和可能的量子简并。这一结果将有助于我们对二维激子多体相互作用的理解，并为在紧凑的二维器件中实现宏观相干奠定基础。对这些自旋极化激子的研究也将阐明玻色子的自旋极化如何影响关联和进一步的宏观一致性的形成。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。