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，其电子性质会发生巨大的变化。具有单原子厚度的过渡金属二硫属化物（TMD）半导体家族具有独特的电子和光学特性，可以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项目通过多功能实验控制研究这些新材料的特性，以了解和利用它们来实现具有改进性能和操作方案的新器件概念。该研究支持在低能量电子和传感方面特别相关的电子设备应用。如果成功，该项目还为未来基于FPGA的计算平台奠定了基础，该平台有望实现（1）更小的设备尺寸和更高的集成度，（2）具有更高计算能力和效率的新计算模式，以及（3）具有增强信息安全性的新通信协议。多名研究生和本科生正在通过这个项目在跨学科的研究环境中接受教育。目前正在开展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者的培训，包括：（1）针对跨学科学生，开发一门新的器件物理课程;（2）通过为物理学本科生提供一个新的低温物理实验模块，加强已经确立的“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就K-12教育和外展建立伙伴关系，提高公众对先进纳米技术和固态物理的认识。电子自旋-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状态。在过渡金属二硫属化物（TMD）中，电子自旋被有效地锁定到另一个量子自由度，谷。这提供了定义和操纵具有潜在增强的寿命和鲁棒性的自旋谷量子比特的新方法，因为利用电和磁波动意外地翻转谷量子自由度要困难得多。 此外，与传统半导体相比，TMD中的面内静电相互作用要强得多，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长距离量子通信所必需的过程。这项职业研究的重点是通过电学和光学量子测量研究门定义的TMD纳米结构中的奇异量子现象，并提供新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，可调强面内和垂直电子耦合，以及电子和光学状态之间量子信息的相干转换。 通过研究静电控制的量子隧穿过程，这个职业项目还提供了与小能量尺度相关的材料指标的敏感表征，这些小能量尺度是传统传输和光学研究难以获得的。更复杂的门定义的纳米结构提供了研究新的自旋谷锁定库仑阻力和自旋谷极化介观量子物理的平台，这为新型量子器件概念（如谷电子学和自旋谷量子比特）提供了基础。门定义的量子限制和操纵的光激发允许新的激子和凝聚物理的研究与可调约束增强大激子结合energy.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.