MACROSCOPIC PHASE COHERENCE FROM SYNTHETIC INTERLAYER COUPLING IN VAN DER WAALS FLAT BANDS

非技术描述：许多壮观的物理现象--以及有用的装置--都依赖于宏观量子相干。最著名的例子是超导体，在超导体中，宏观相干与没有电阻以及相干自由度的出现直接相关，这些自由度构成了最发达的操纵量子信息的平台的基础。然而，宏观量子相干在原则上是一个更广泛的现象。这个项目的目标是在一大类被称为范德华异质结构的材料中实现宏观量子相干的新模式。范德华异质结构由石墨烯等连续层状的二维原子晶体组成，其高度的晶体完备性和广泛的可调谐范围使各种新的量子相干态进入了实验范围。通过实现以宏观量子相干为特征的新状态，该项目加深了对这些现象的理解，并为量子信息处理开辟了新的途径。与研究工作的协同是一项专注于技术劳动力发展的教育倡议，通过为从事量子科学相关问题的物理、化学和材料科学的研究生举办的暑期学校实施。技术描述：该项目的最终目标是在双层激子凝聚体中创建一种基于层间相干的新型量子比特。该比特利用了预测将在这些系统中发生的自发相干性。双层激子凝聚体最早是在半导体量子阱中发现的，最近被证明存在于石墨烯和硫化物异质结构中，温度较高，实验条件要求较低--特别是在没有磁场的情况下。该研究小组正在使用频率相关的层间隧道光谱，通过激子模拟交流约瑟夫森效应来直接检测宏观相干性的出现。这一新的检测模式允许在基于频带结构工程的二维双层结构的各种双层结构中广泛搜索宏观一致性。该奖项反映了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。

Non-technical description: Many spectacular physical phenomena—and useful device—rely on macroscopic quantum coherence. The most well known example are superconductors, where macroscopic coherence is directly tied both the absence of electrical resistance as well as the emergence of coherent degrees of freedom that form the basis for the best developed platforms for manipulating quantum information. However, macroscopic quantum coherence, in principle, a much broader phenomenon. This project aims to realize new modalities of macroscopic quantum coherence in a broad class of materials known as van der Waals heterostructures. Van der Waals heterostructures consist of successively laminated two dimensional atomic crystals such as graphene; their high crystalline perfection and broad range of tunability put a variety of new quantum coherent states in experimental range. By realizing new states characterized by macroscopic quantum coherence, this project furthers understanding of these phenomena and opens new avenues towards quantum information processing. Synergistic with the research effort is an educational initiative focused on technical workforce development, implemented through a summer school for graduate student across physics, chemistry and materials science working on quantum science related problems. Technical description:The ultimate goal of this project is to create a novel quantum bit based on interlayer coherence in a bilayer exciton condensate. This bit exploits the spontaneous phase coherence predicted to occur in these systems. Bilayer exciton condensates, first discovered in semiconductor quantum wells, have recently been shown to exist in graphene and chalcogenide heterostructures at higher temperatures and under less demanding experimental conditions—particularly in the absence of magnetic fields. The research team is using frequency-dependent interlayer tunneling spectroscopy to directly detect the emergence of macroscopic phase coherence through the excitonic analog of the AC Josephson effect. This new detection modality then allows a broad search for macroscopic coherence in a variety of double layer structures based on band-structure engineered two dimensional double layers.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.