CAREER: Mesoscopic Quantum Opto-Electronics in Gate-Defined Transition Metal Dichacogenide Nanostructures

当固体的厚度减小到原子极限时，它的电子特性会发生巨大的变化。具有单原子厚度的半导体家族，过渡金属二硫族化合物（TMD），具有独特的电子和光学特性，可以潜在地为未来电子和计算平台中的许多剩余挑战提供解决方案。这个CAREER项目通过多种实验控制来研究这些新材料的特性，以理解和利用它们来实现具有改进性能和操作方案的新设备概念。这项研究为电子设备的应用奠定了基础，特别是在低能量电子和传感方面。如果成功，该项目还为未来基于半导体的计算平台奠定了基础，该平台承诺(1)更小的设备尺寸和更高级别的集成，(2)具有更高计算能力和效率的新计算范式，以及(3)具有增强信息安全的新通信协议。多名研究生和本科生通过这个项目在一个跨学科的研究环境中接受教育。正在实施一系列教育和推广工作，旨在加强对下一代科学和工程工作人员的培训，包括(1)开发面向跨学科学生的设备物理新课程，(2)通过为物理本科生提供低温物理实验的新模块，加强完善的“实验物理方法”课程。(3)招募代表性不足的群体参与跨学科研究，并与明尼苏达科学博物馆合作开展K-12教育和推广，提高公众对先进纳米技术和固态物理的认识。电子自旋是量子化角动量的一种形式，被广泛用于定义单个量子比特的0和1态。在过渡金属二硫族化合物（TMDs）中，电子自旋被有效地锁定在另一个量子自由度，谷。这为定义和操纵具有潜在增强寿命和鲁棒性的自旋谷量子比特提供了新的方法，因为在电和磁波动的情况下，不小心翻转谷量子自由度要困难得多。此外，与传统半导体相比，tmd中的平面内静电相互作用要强得多，从而允许可控的光物质相互作用。这可以用来将电子量子信息转换为光子态，这是未来电子量子计算机之间远距离量子通信所必需的过程。本CAREER研究的重点是通过电学和光量子测量来研究门定义TMD纳米结构中的奇异量子现象，并提供新的量子器件功能的原理证明，例如组合自旋谷量子自由度的操纵，可调谐的强平面内和垂直电子耦合，以及电子和光态之间量子信息的相干转导。通过研究静电控制的量子隧穿过程，该CAREER项目还提供了与小能量尺度相关的材料指标的敏感表征，这是传统输运和光学研究难以获得的。更为复杂的门定义纳米结构为研究新型自旋锁谷库仑阻力和自旋谷极化介观量子物理提供了平台，为谷电子学和自旋谷量子比特等新型量子器件概念提供了基础。门定义量子约束和光激发的操纵允许研究具有可调约束增强的大激子结合能的新型激子和凝聚态物理。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。

The electronic properties of a solid can undergo dramatic change when its thickness is reduced to the atomic limit. A family of semiconductors with single-atom thickness, transition metal dichalcogenides (TMD), host unique electronic and optical properties that can potentially provide solutions to many remaining challenges in future electronics and computing platforms. This CAREER project investigates these novel material properties with versatile experimental control, towards understanding and harnessing them in realizing novel device concepts with improved performance and operation schemes. The research underpins electronic device applications that can be particularly relevant in low energy electronics and sensing. If successful, the project also lays a foundation towards future semiconductor-based computing platforms that promises (1) smaller device dimensions and higher-level integration, (2) new computation paradigms with higher computational power and efficiency, and (3) new communication protocols with enhanced information security. Multiple graduate students, and undergraduates are being educated through this project in an interdisciplinary research environment. A series of educational and outreach efforts are being implemented, aimed towards enhanced training of the next generation scientific and engineering work-force, including (1) development of a new course on device physics directed towards an interdisciplinary student audience, (2) enhancing the well-established "Method for Experimental Physics" course by providing a new module of low-temperature physics experiments for physics undergraduate students, (3) and recruitment of underrepresented groups into interdisciplinary research and partnership with the Science Museum of Minnesota on K-12 education and outreach, promoting public awareness toward the advanced nanotechnologies and solid-state physics. Electron spins – a form of quantized angular momentum, are widely used to define the 0 and 1 states of a single quantum bit. In transition metal dichalcogenides (TMDs), the electron spin is effectively locked to another quantum degree of freedom, valley. This provides new ways of defining and manipulating a spin-valley quantum bit with potentially enhanced life time and robustness, as it is much more difficult to accidentally flip the valley quantum degree of freedom with electrical and magnetic fluctuations. In addition, the in-plane electrostatic interactions in TMDs are much stronger compared to conventional semiconductors, allowing controllable light-matter interaction. This can be utilized to convert the electronic quantum information to photonic states, a process essential for long distance quantum communication between future electronic quantum computers. This CAREER research focuses on studying exotic quantum phenomena in gate-defined TMD nanostructures via electrical and optical quantum measurements and providing proof-of-principle demonstration of new quantum device functionalities, such as manipulation of the combined spin-valley quantum degree of freedom, tunable strong in-plane and vertical electron coupling, and coherence transduction of quantum information between electronic and optical states. By studying electrostatically-controlled quantum tunneling processes, this CAREER project also provides sensitive characterization of material metrics associated with small energy scales that are difficult to access with conventional transport and optical studies. The more complicated gate-defined nanostructures provide platforms to study novel spin-valley-locked Coulomb drag and spin-valley polarized mesoscopic quantum physics, which provides a basis for novel quantum device concepts such as valleytronics and spin-valley qubits. Gate-defined quantum confinement and manipulation of optical excitations allow the study of novel exciton and condensate physics with tunable confinement-enhanced large exciton binding energy.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.