Quantum Coherence and Dynamical Instability in Quantum Wells Driven by Intense Terahertz Fields.

强太赫兹场驱动的量子井中的量子相干性和动态不稳定性。

• 批准号: 1006603
• 负责人: Mark Sherwin
• 金额: $ 56万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1006603&HistoricalAwards=false
• 关键词: Quantum; Coherence; Dynamical; Instability; Wells

****NON-TECHNICAL ABSTRACT****Beginning when early humans harnessed fire for heat and light, the control of electromagnetic radiation has been central to the development of our species. The notion of electromagnetic radiation is nearly 150 years old, proposed by Maxwell in 1865 and demonstrated with the discovery of radio waves in 1866. Radio waves remained largely a laboratory curiosity for nearly 50 years. It is difficult to imagine modern life without radio waves, microwaves, heat, light, and X-rays, which are now all understood to be manifestations of electromagnetic radiation, listed in order of increasing frequency. However, lying between the frequencies of microwaves and heat, stretching from 0.1 to 10 trillion cycles per second (0.1-10 terahertz) is the so-called 'terahertz gap.' Electromagnetic waves exist in this frequency range, but they are extremely difficult to generate and control. This individual investigator award supports a project that will use the world's brightest pulses of terahertz waves, generated by accelerator-driven 'free-electron lasers', to search for new quantum-mechanical phenomena predicted to occur in nanometers-thick semiconductor devices. The semiconductor devices under study are similar to those used to modulate light in fiber-optic communications, and as ultrafast transistors in cellular telephones. This project will support the education of two PhD students, as well as undergraduate and high-school interns. The students will learn the most advanced techniques to generate and manipulate electromagnetic radiation across the electromagnetic spectrum, preparing them for leadership in the nation's scientific and technological workforce, and bringing mankind closer to harnessing terahertz radiation for future technologies. ****TECHNICAL ABSTRACT****Strong oscillating electric fields with frequencies between 1 and 5 THz are increasingly available in laboratories and even inside chip-scale devices like terahertz quantum cascade lasers. A growing body of theory predicts that fascinating and potentially useful phenomena will occur in semiconductor quantum wells driven by strong THz fields. For example, calculations based on commonly used approximations for many-electron systems predict that chaotic dynamics can occur in doped quantum wells for experimentally-achievable conditions. The observation of chaotic dynamics in an experiment on a manifestly quantum system would be very surprising, since chaos arises from nonlinearities while quantum mechanics is a linear theory. This project will support experimental searches for precursors of chaotic dynamics in doped quantum wells. The intense terahertz radiation necessary for these experiments will be generated by free-electron lasers at UC Santa Barbara and in Dresden, Germany. This project will also support studies of how strong terahertz radiation changes the quantum states and band structure of semiconductors and semiconductor quantum wells, as measured by terahertz-induced changes in the near-infrared absorption and emission. Two PhD students will receive deep and broad training in semiconductor physics, nanofabrication, optics at terahertz, near-IR and visible frequencies, mechanical design, cryogenics, electronics, and computer control of laboratory instrumentation, as well as in international collaboration, preparing them for leadership in the nation's science and technology workforce. The supported PhD students will also mentor a diverse group of undergraduate researchers and high-school student interns, sparking their interest in pursuing careers in science or engineering.

****非技术抽象****从早期人类利用火力和光线开始时，电磁辐射的控制一直是我们物种发展的核心。 电磁辐射的概念将近150年，由麦克斯韦（Maxwell）于1865年提出，并在1866年发现无线电波证明。无线电波在很大程度上保持了近50年的实验室好奇心。 很难想象没有无线电波，微波，热，光和X射线的现代生活，现在都被认为是电磁辐射的表现，以增加频率的顺序列出。 然而，位于微波和热量的频率之间，从0.1到10万亿周期（0.1-10 Terahertz）是所谓的“ Terahertz Gap”。 电磁波存在于此频率范围内，但是它们很难产生和控制。 该单独的研究者奖支持将使用由加速器驱动的“自由电子激光器”产生的世界上最亮的Terahertz波脉冲来搜索预计将发生在纳米剂中的新量子机械现象。 所研究的半导体设备类似于用于调节光纤通信中光线的设备，并作为细胞电话中的超快晶体管。 该项目将支持两名博士学位学生以及本科和高中实习生的教育。 学生将学习最先进的技术，以在电磁频谱上产生和操纵电磁辐射，为他们在国家科学和技术劳动力中的领导作品做好准备，并使人类更接近利用Terahertz辐射来利用Terahertz辐射来实现未来技术。 ****技术摘要****在实验室，甚至在Terahertz Quantum Cascade Lasers等芯片尺度设备中，越来越多地使用具有1到5 THZ的强振荡电场。 越来越多的理论体系预测，在强大的THZ场驱动的半导体量子井中将出现引人入胜且潜在的现象。 例如，基于许多电子系统的常用近似值的计算预测，在掺杂的量子井中可能发生混沌动力学，以实现实验性的条件。 在明显的量子系统上对混乱动力学的观察将非常令人惊讶，因为混乱是由非线性引起的，而量子力学是线性理论。 该项目将支持掺杂量子井中混沌动力学的前体的实验搜索。 这些实验所需的强烈的terahertz辐射将由加州大学圣巴巴拉分校和德国德累斯顿的自由电子激光器产生。 该项目还将支持强烈的Terahertz辐射如何改变半导体和半导体量子井的量子状态和带状结构，这是通过Terahertz诱导的近红外吸收和排放的变化来衡量的。 两名博士学位学生将接受半导体物理学，纳米化，Terahertz的光学培训，附近IR和可见频率，机械设计，低温，电子学，电子学和实验室仪器的计算机控制，以及国际合作，为他们在国家科学和技术工作的领导力做好准备。 支持的博士生还将指导一群多样化的本科研究人员和高中生实习生，这引发了他们从事科学或工程职业的兴趣。