CAREER: Excitonic condensation in double-layer graphene: phases, transport and photoluminescence properties, and the BCS-BEC crossver.

该职业奖支持探索双层石墨烯及相关体系中激子凝聚物的相、集体激发、输运和光致发光特征的理论研究。利用动量空间平均场分析、互补实空间紧密结合方法和有效作用方法，PI将重点关注以下开放性问题：1)均匀态和结晶态激子凝聚体的输运和光致发光性质是什么？2)电子屏蔽、磁场、表面曲率如何影响它们？3)（非均匀）凝析油中BEC-BCS交叉的特征是什么？4)双层石墨烯体系的结果与其他二维体系的结果有什么不同？该提案的教育和推广部分包括培训和指导一名博士后、一名研究生以及本科生和高中生。PI将让高中生和大学生参与研究和学术活动，强调教科书学习和研究的双重性。这项研究将被转化为独立的教学模块，可以纳入本科课程。K-12学生的实践研究经验将通过网站和学校访问定期传播令人兴奋的科学发现。本职业奖支持理论研究，探索“激子凝聚体”在相对较新的材料类别中的可能性和各种特性。当光与半导体或绝缘体相互作用并将一个电子从已占据的量子态激发到未占据的量子态时，留下一个有效的正电荷，称为“空穴”，带负电荷的电子和带正电荷的空穴之间的静电相互作用导致这两个实体形成一个束缚态，称为“激子”。由于量子力学定律，激子有可能凝聚成相同的最低能态，或者形成一种类似液体的状态，在这种状态下，激子可以不带任何粘度地流动，从而形成“激子凝聚体”。虽然这种冷凝物在技术上很重要，因为它们使零电阻电子输运和相干光源成为可能，但由于材料的性质不能广泛调节，实现它们的进展一直受到阻碍。最近，一种被称为石墨烯的二维碳原子蜂窝网络已经成为一种非常通用、清洁和可调的电子材料。认为石墨烯是实现激子凝聚体的有希望的候选者。PI将研究在不同情况下两层石墨烯堆叠在一起的系统中激子凝聚的可能性，并预测它们在电传输和光发射测量中的特征。该研究还将解决激子凝聚的基本问题，其结果有望适用于各种各样的系统。该提案的教育和推广部分包括培训和指导一名博士后、一名研究生以及本科生和高中生。PI将让高中生和大学生参与研究和学术活动，强调教科书学习和研究的双重性。这项研究将被转化为独立的教学模块，可以纳入本科课程。K-12学生的实践研究经验将通过网站和学校访问定期传播令人兴奋的科学发现。

TECHNICAL SUMMARYThis CAREER award supports theoretical research that explores the phases, collective excitations, and transport and photoluminescence signatures of excitonic condensates in double-layer graphene and related systems. Using momentum-space mean-field analysis, the complementary real-space tight-binding method, and the effective action approach, the PI will focus on the following open questions:1) What are the transport and photoluminescence properties of uniform and crystalline excitonic condensates? 2) How do electronic screening, magnetic field, and the surface curvature affect them? 3) What are the signatures of BEC-BCS crossover in (non-uniform) condensates? 4) What are the differences between the results for a double-layer graphene system and other two-dimensional systems? The educational and outreach component of the proposal involves the training and mentoring of a postdoctoral fellow, a graduate student, as well as undergraduate and high school students. The PI will involve high school and undergraduate students in research and scholarly activities that emphasize the duality between textbook learning and research. The research will be translated into self-contained pedagogical modules that can be incorporated into the undergraduate curriculum. The hands-on research experience for K-12 students will be complemented with periodic dissemination of exciting discoveries in science through a website and school-visits.NON-TECHNICAL SUMMARYThis CAREER award supports theoretical research that explores the possibilities and various properties of "excitonic condensates" in a relatively new class of materials. When light interacts with semiconductors or insulators and excites an electron from an occupied quantum state to an unoccupied one leaving behind an effective positive charge called the "hole", the electrostatic interaction between the negatively charged electron and the positively charged hole results in the formation of a bound state of these two entities called the "exciton". Due to quantum mechanical laws, it is possible for excitons to condense into the same lowest-energy state or form a liquid-like state in which they can flow without any viscosity, thereby forming "excitonic condensates". While such condensates are technologically important because they make zero-resistance electronic transport and coherent sources of light possible, progress towards their realization has been has been hampered due to materials whose properties are not widely tunable. Recently, a two-dimensional honeycomb network of carbon atoms, called graphene, has emerged as an exceptionally versatile, clean, and tunable electronic material. It is believed that graphene is a promising candidate for the realization of excitonic condensates. The PI will investigate the possibilities of excitonic condensation in a system of two layers of graphene stacked on top of another under various circumstances, and predict their signatures in electrical transport and light-emission measurements. The research will also address fundamental questions about excitonic condensates, and the results are expected to be applicable to a wide variety of systems. The educational and outreach component of the proposal involves the training and mentoring of a postdoctoral fellow, a graduate student, as well as undergraduate and high school students. The PI will involve high school and undergraduate students in research and scholarly activities that emphasize the duality between textbook learning and research. The research will be translated into self-contained pedagogical modules that can be incorporated into the undergraduate curriculum. The hands-on research experience for K-12 students will be complemented with periodic dissemination of exciting discoveries in science through a website and school-visits.