Ultrafast nanoscale quantum dynamics of materials

材料的超快纳米级量子动力学

• 批准号: RGPIN-2022-04361
• 负责人: Hegmann, Frank
• 金额: $ 6.92万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762487
• 关键词: Ultrafast; nanoscale; quantum; dynamics; materials

Ultrafast nanoscale quantum dynamics of materials The proposed research program uses leading-edge experimental tools to explore ultrafast quantum processes in materials and devices down to the atomic scale. One of the main objectives is to directly image and control ultrafast quantum processes and excitations on surfaces with atomic resolution. There are many fundamental interactions and dynamics of charge carriers and excitations in materials that occur over picosecond time scales (0.1 - 1000 ps) and nanometer length scales (1 - 1000 nm) all the way down to single molecules and atoms (< 0.3 nm). For example, electrons in semiconductors and device structures such as solar cells can diffuse distances of 100 nm over 4 ps time scales. However, direct imaging of how carrier diffusion in materials is affected by the local atomic environment has been challenging. In superconductors, the recombination time of normal-state electrons back into superconducting Cooper pairs ranges from 10-400 ps, and superconducting nanowire single-photon photodetectors that produce nanometer-sized normal-state regions upon absorption of a photon have exhibited ultrafast response times around 50 ps. However, no one has ever directly imaged picosecond nonequilibrium dynamics in superconductors on the nanoscale. In addition, one of the main goals in physics is to directly image the ultrafast dynamics of quantum mechanical wave functions in nanostructures and molecules. Clearly, the ability to directly probe materials and devices on sub-ps time scales and sub-nm length scales will have a significant impact on our understanding of why they behave the way they do and will enable us to develop new device technologies. In the proposed research program, we will use time-resolved terahertz spectroscopy (TRTS) and terahertz scanning tunneling microscopy (THz-STM) to probe and directly image ultrafast nanoscale quantum processes in materials. Femtosecond laser sources are used to generate optical excitation pulses as well as single-cycle, ps-duration terahertz (THz) pulses. TRTS will be used to explore nanoscale ultrafast conductivity dynamics and carrier transport in films of semiconductor nanowires and nanocrystals, as well as in quantum materials and nanostructures. THz-STM, which was developed in our lab, couples THz pulses to the sharp metal tip of an STM and will be used to directly image ultrafast quantum processes in materials down to the atomic scale. A recently awarded CFI Innovation Fund, Ultrafast Nanoscale Quantum Dynamics (UltraNanoQD), will allow for the development of (i) ambient THz-STM for rapid sample turnaround and (ii) a unique multi-probe THz-STM system with four independently-controlled STM tips for unprecedented imaging and control of ultrafast nanoscale dynamics in quantum materials and devices. This will revolutionize how we do THz-STM, providing a new window into fundamental ultrafast processes in materials and devices on the atomic scale.

材料的超快纳米级量子动力学拟议的研究计划使用领先的实验工具来探索材料和设备中原子量表中的超快量子过程。主要目标之一是直接对具有原子分辨率的表面上的超快量子过程和激发。 在皮秒时间尺度（0.1-1000 ps）和纳米长度尺度（1-1000 nm）上发生的材料中，电荷载体的基本相互作用和动力学一直降低到单分子和原子（<0.3 nm）。例如，半导体和设备结构（例如太阳能电池）中的电子可以在4 ps的时间尺度上扩散100 nm的距离。但是，直接对材料中的载体扩散如何受到局部原子环境的影响一直具有挑战性。在超导体中，正常状态电子的重组时间重组为超导库珀对，范围为10-400 ps，以及在吸收光子吸收后产生纳米大小的正常状态区域的超导纳米型单光子光电检测器显示了超出响应时间约50 ps。但是，没有人直接成像纳米级超导体中的皮秒非平衡动力学。此外，物理学的主要目标之一是直接成像纳米结构和分子中量子机械波的超快动力学。显然，在子PS时间尺度和子NM长度尺度上直接探测材料和设备的能力将对我们对它们的行为方式的理解产生重大影响，并使我们能够开发新的设备技术。 在拟议的研究计划中，我们将使用时间分辨的Terahertz光谱（TRT）和Terahertz扫描隧道显微镜（THZ-STM）来探测并直接对材料中的超快纳米级量子过程进行探测。飞秒激光源用于产生光激发脉冲以及单周期，PS-Duration Terahertz（THz）脉冲。 TRT将用于探索半导体纳米线和纳米晶体以及量子材料和纳米结构中的纳米级超快电导率和载体传输。 THZ-STM是在我们的实验室中开发的，夫妻THZ脉冲与STM的尖锐金属尖端，并将用于直接成像材料中的超快量子过程，直至原子尺度。 A recently awarded CFI Innovation Fund, Ultrafast Nanoscale Quantum Dynamics (UltraNanoQD), will allow for the development of (i) ambient THz-STM for rapid sample turnaround and (ii) a unique multi-probe THz-STM system with four independently-controlled STM tips for unprecedented imaging and control of ultrafast nanoscale dynamics in quantum materials and devices.这将彻底改变我们如何进行THZ-STM，为原子规模上的材料和设备的基本超快过程提供新的窗口。