Realizing High Temperature Exciton Condensates at Molecule/2D van der Waals Interfaces

非技术性描述：由于具有不同性质的二维（2D）货车德瓦尔斯层状材料可以在纳米尺度上组装，因此它们已经被用来实现许多传统材料中不具备的电子相。在该项目中，研究团队将有机分子与2D分层晶体结合，实现激子的高温玻色-爱因斯坦凝聚体（BEC）。BEC是一种宏观量子态，具有许多有趣的性质，如无摩擦输运。BEC的宏观性质使其适合于量子信息科学应用。目前，由于BEC通常仅存在于超冷（1 K）原子气体中，因此BEC的应用受到限制。该项目的目标是在更高的温度（100 K）下在固态半导体中生产BEC，以便其新颖的特性可以用于更传统的电子设备。该项目培训本科生和研究生在纳米材料设计，制造和表征在协作环境。重点是从代表性不足的群体中招收学生。与2D/2D异质结构相比，分子/2D异质结构中的分子晶格可以为电子结构提供额外的可调谐性。该团队利用分子的功能为层间激子建立周期性捕获电势，周期小至1 - 2纳米。使用这种方法，我们的目标是增加1 - 2个数量级的激子密度相比，在2D/2D异质结构中可实现的最大激子密度。高密度的捕获激子可以使我们在更高的温度（100 K）下实现BEC相。此外，稳态和时间分辨光谱和显微镜，光电子能谱和时间相关光子计数技术将被用来表征和理解BEC的光学和传输特性。该项目的目标是证明BEC在高温下的相干光子发射和无耗散传输。该奖项反映了NSF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。

Nontechnical description: Because two-dimensional (2D) van der Waals layered materials with different properties can be assembled on the nanoscale, they have been used to realize many electronic phases that are not available in traditional materials. In this project, the research team combines organic molecules with 2D layered crystals to realize high temperature Bose-Einstein condensate (BEC) of excitons. The BEC is a macroscopic quantum state that has many interesting properties such as frictionless transport. The macroscopic nature of the BEC makes it suitable for quantum information science applications. Currently, because BECs typically exist only in ultracold ( 1 K) atomic gases, the applications for BECs are limited. The project aims to produce BECs in solid-state semiconductors at a much higher temperature ( 100 K) so that its novel properties would be utilized in more conventional electronic devices. The project trains undergraduate and graduate students in nanoscale material design, fabrication, and characterization in a collaborative environment. Emphasis is placed on recruiting students from underrepresented groups. Outreach activities to the public include a summer camp for K-12 students and outreach seminars.Technical description: Compared to 2D/2D heterostructures, the molecular lattice in molecule/2D heterostructures can provide added tunability to the electronic structure. The team utilizes functionalities of molecules to build periodic trapping potentials for interlayer excitons with a period as small as 1 – 2 nanometers. Using this approach, we aim to increase the density of excitons by 1 - 2 orders of magnitude as compared to the maximum exciton density achievable in 2D/2D heterostructures. A high density of trapped excitons can enable us to realize the BEC phase at higher temperatures ( 100 K). Moreover, steady-state and time-resolved optical spectroscopy and microscopy, photoemission spectroscopy, and time-correlated photon counting techniques will be used to characterize and understand BEC’s optical and transport properties. The goal of this project is to demonstrate the coherent photon emission and the dissipationless transport of the BEC at high temperatures.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.