Investigating many-body states of interlayer excitons in 2D atomic double layers

非技术性：玻色-爱因斯坦凝聚是近一个世纪前玻色和爱因斯坦预测的一种物质状态，并且已经在接近绝对零度的稀释原子气体中实现。这一发现导致了科学、精确测量和量子信息的巨大进步。然而，进一步技术进步的一大障碍是产生这些冷凝物所需的极低温度。在这个项目中，研究小组开发了一种在高温（100 K）下形成的新型玻色-爱因斯坦凝聚体。人造原子形成在原子薄的材料薄膜中，这些薄膜是一层一层堆叠起来的。这可能会导致高温超导体以及具有前所未有性能的光电、光子和量子器件的发展。该项目培训研究生和本科生，使他们成为新兴量子技术的劳动力。该小组还编写外联材料，以鼓励和扩大年轻学生的参与。技术：在接近绝对零度的温度下，原子的稀释气体发生玻色-爱因斯坦凝聚（BEC）。由于质量小得多，激子（束缚的电子-空穴对）预计会在相当高的温度下凝结。二维层状半导体的出现，具有很强的激子结合（约半电子伏特）和形成范德华异质结构的灵活性，为探索高温激子凝聚态和其他涌现的量子多体基态开辟了一个令人兴奋的新机会。该研究项目建立在首席研究员之前在范德华异质结构方面的工作和专业知识的基础上，旨在开发用于激子凝聚和基于激子凝聚的光电子学和光子学应用的新型固态结构。通过优化设计双层结构和基于电输运和光学测量的实验探针阵列，该团队旨在实现三个目标。(i)寻找过渡金属二硫化物双层中激子凝聚的直接证据，例如远距离空间相干性；（ii）将BEC区内及BEC附近的激子凝聚温度-密度相图映射为bardeen - coopero - schrieffer （BCS）交叉；(3)寻找由小间隙半导体组成的双层体系中的平衡激子凝聚体。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。

Nontechnical: Bose-Einstein Condensates are a state of matter predicted by Bose and Einstein nearly a century ago and has been realized in dilute gases of atoms at temperatures close to absolute zero. This discovery has led to tremendous advances in science, precision measurements and quantum information. However, one big hurdle for further technological advances is the extremely low temperature that is required to create these condensates. In this project, the research team develops a new type of Bose-Einstein Condensates formed at high temperatures (100 K). The artificial atoms are formed in atomically thin membranes of materials that are stacked layer-by-layer. This could result in development of high temperature superconductors and optoelectronic, photonic and quantum devices with unprecedented properties. The project trains graduate and undergraduate students, preparing them as workforce in emerging quantum technologies. The team also develops outreach materials for use in inspiring and broadening participation among young students.Technical: Bose-Einstein condensation (BEC) of a dilute gas of atoms occurs at temperatures close to absolute zero. With much smaller mass, excitons (bound electron-hole pairs) are expected to condense at considerably higher temperatures. The emergence of two-dimensional layered semiconductors with very strong exciton binding (about half an electron volt) and flexibility in forming van der Waals heterostructures has opened a new exciting opportunity to explore high-temperature exciton condensate and other emergent quantum many-body ground states. This research project builds on the principal investigator’s prior works and expertise in van der Waals heterostructures and aims to develop new solid-state structures for exciton condensation and exciton condensate-based applications in optoelectronics and photonics. By using optimized design of the double layer structure and an array of experimental probes based on electrical transport and optical measurements, the team aims to achieve three objectives. (i) Search for direct evidence of exciton condensation in transition metal dichalcogenide (TMD) double layers such as long-range spatial coherence; (ii) Map the exciton condensation temperature - density phase diagram in the BEC regime and near the BEC to Bardeen-Cooper-Schrieffer (BCS) crossover; (iii) Search for equilibrium exciton condensates in double layer systems consisting of small gap semiconductors.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.