EFRI 2-DARE: Excitonics and Polaritonics using 2D materials (ExPo2D)

纯二维(2D)碳原子层石墨烯的特殊性质促使人们发现了一系列具有特殊电子、机械、光学和热学性质的2D材料系统。这些新的2D材料有望带来新一代技术，如柔性显示、超高速计算、高效率低成本太阳能电池和量子信息处理。特别是在光电子学的背景下，2D材料异常强大的光-物质相互作用使其在实际设备应用中具有极大的吸引力。然而，单层石墨烯没有直接带隙，这限制了其在一系列光电子应用中的应用。最近发现的基于过渡金属二卤化物的2D原子晶体，其中许多在可见光和红外光谱上具有很大的带隙，现在开辟了光学和光电子器件的全新研究领域。在这项计划中，将基于对电子激发态、混合半轻半物质准粒子(激子-极化子)和二维过渡金属二卤化物中集体激发的精确控制，开发用于下一代经典和量子信息处理的积木。其目的是开发下一代光电子系统和子系统，利用2D半导体的独特优势，如与光的相互作用强度大，机械灵活性和低制造成本。具体地说，(I)将使用中性和带电激发来开发低能耗的超快逻辑门(Ii)将使用极化子来研究即使是单个光子也可以改变系统状态的量子非线性器件，以及(Iii)将使用集体激发来探索依赖于数学拓扑学思想的物质的奇异相。牵头机构CCNY是一家为少数族裔服务的机构，通过与麻省理工学院的密切合作，预计来自不同种族和社会背景的研究生和本科生将成为拟议的尖端研究的一部分。该方案还将为当地代表性不足的少数民族高中学生/教师提供教育机会，并让他们参与暑期项目。将科学带给公众的推广工作是该计划下的另一项有针对性的努力。该计划将开发基于过渡金属二卤化物(MoS2、WS2、WSe2等)的2D原子层在可见光和近红外光谱范围内工作的激子和极化(激子-光子准粒子)设备。这种2D材料本身就与光有很强的相互作用，并具有其他吸引人的性质，如谷极化和强烈的自旋-轨道耦合。这些独特的性质为开发迄今无法访问的器件特征开辟了道路，在经典和量子信息处理中具有巨大的潜在应用。依赖于控制激子和极化子的传输和局域化以及在2D材料中出现拓扑相的方法的器件将是本计划的重点。具体地说，使用2D过渡金属二卤化物及其异质结构的器件/器件概念将被开发：(I)利用中性和带电激子的晶体管和逻辑门，(Ii)基于激子极化子的量子非线性光学器件和光发射器，以及(Iii)可以在2D半导体中实现的基于拓扑相的探索性光电子器件概念。器件的开发将受到生长和合成工作的密切指导，以及更好地理解激子和极化子输运以及实现用于电子能带结构操纵的新型拓扑相和应变工程的理论努力的指导。基于2D半导体的激子和极化子器件的发展具有在室温下工作的潜力，这为利用以前未探索的基本物理概念开发实用器件提供了一个独特的机会。

The exceptional properties of the purely two-dimensional (2D) sheet of carbon atoms, graphene, has spurred the discovery of a whole host of 2D material systems with exceptional electronic, mechanical, optical and thermal properties. These new 2D materials promise a new generation of technologies such as flexible displays, ultrafast computing, high-efficiency low-cost solar cells, and quantum information processing. Specifically in the context of optoelectronics, the unusually large strength of light-matter interaction of 2D materials has made them highly attractive for practical device applications. However, single-layer graphene has no direct bandgap, which limits its use in a range of optoelectronic applications. The recent discovery of 2D atomic crystals based on transition metal dichalcogenides, many of which have large bandgaps in the visible and infrared spectrum, now opens entirely new areas of investigation in optical and optoelectronic devices. In this program, building blocks for next generation classical and quantum information processing will be developed based on precise control of electronic excited states, hybrid half-light half-matter quasiparticles (exciton-polaritons), and collective excitations in 2D transition metal dichalcogenides. The motivation is to develop next generation photonic and electronic systems and sub-systems that exploit the unique advantages of 2D semiconductors such as large interaction strength with light, mechanical flexibility, and low fabrication cost. Specifically, (i) low energy consuming, ultrafast logic gates will be developed using neutral and charged excitations (ii) Quantum nonlinear devices where even a single photon can alter the state of the system will be investigated using polaritons and (iii)Exotic phases of matter that rely on ideas from mathematical topology will be explored using collective excitations will be developedIn addition to the technological impact on society, the program will include extensive Educational and Outreach. CCNY, the lead institution, is a minority-serving institution and through close collaboration with MIT expects both graduate and undergraduate students from diverse ethnic and social backgrounds to become part of the proposed cutting-edge research. The program will also provide educational opportunities for local underrepresented minority high school students/teachers and will engage them in summer projects. Outreach efforts for bringing the science to the general public is another targeted effort under the program. This program will develop excitonic and polaritonic (exciton-photon quasiparticles) devices that operate in the visible and near infrared spectral range based on 2D atomic layers of transition metal dichalcogenides (MoS2, WS2, WSe2 etc). The 2D materials have an inherently strong interaction with light and other attractive properties such as valley polarization and strong spin-orbit coupling. These unique properties open up avenues for the development of heretofore inaccessible device features with tremendous potential applications in classical and quantum information processing. Devices that rely on control of exciton and polariton transport and localization as well as approaches to emergent topological phases in 2D materials will be the focus of this program. Specifically, the following devices/ device concepts using 2D transition metal dichalcogenides and their heterostructures will be developed: (i) transistors and logic gates that utilize neutral and charged excitons, (ii) quantum nonlinear optical devices and light emitters based on exciton polaritons, and (iii) exploratory optoelectronic device concepts based on topological phases that can be realized in 2D semiconductors. The device development will be closely guided by growth and synthesis efforts as well as theoretical efforts to better understand exciton and polariton transport and for realizing novel topological phases and strain engineering for electronic band structure manipulation. Development of excitonic and polaritonic devices based on 2D semiconductors that have the potential to operate at room temperature presents a unique opportunity to develop practical devices using previously unexplored fundamental physical concepts.