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.

* 非技术性摘要 * 从早期人类利用火来获取热和光开始，电磁辐射的控制就一直是我们物种发展的核心。 电磁辐射的概念有近150年的历史，由麦克斯韦于1865年提出，并在1866年无线电波的发现中得到证实。 近50年来，无线电波在很大程度上仍然是实验室的好奇心。 很难想象没有无线电波、微波、热、光和X射线的现代生活，现在这些都被认为是电磁辐射的表现形式，按频率增加的顺序列出。 然而，位于微波和热的频率之间，从每秒0.1到10万亿次循环（0.1-10太赫兹）是所谓的“太赫兹间隙”。电磁波在这个频率范围内存在，但它们极难产生和控制。 这个个人研究者奖支持一个项目，该项目将使用世界上最亮的太赫兹波脉冲，由加速器驱动的“自由电子激光器”产生，以寻找预测发生在纳米厚半导体器件中的新量子力学现象。 研究中的半导体器件类似于光纤通信中用于调制光的半导体器件，以及蜂窝电话中的超快晶体管。 该项目将支持两名博士生以及本科生和高中实习生的教育。 学生们将学习最先进的技术，以产生和操纵整个电磁频谱的电磁辐射，为他们在国家的科学和技术劳动力的领导做好准备，并使人类更接近利用太赫兹辐射为未来的技术。 * 技术摘要 * 频率在1到5 THz之间的强振荡电场越来越多地出现在实验室中，甚至出现在太赫兹量子级联激光器等芯片级设备中。 越来越多的理论预测，在强太赫兹场驱动下，半导体量子威尔斯阱中将出现迷人且潜在有用的现象。 例如，基于多电子系统的常用近似的计算预测，对于实验可实现的条件，在掺杂量子威尔斯中可以发生混沌动力学。 在一个明显的量子系统的实验中观察到混沌动力学将是非常令人惊讶的，因为混沌产生于非线性，而量子力学是一个线性理论。 这个项目将支持在掺杂量子威尔斯中混沌动力学前兆的实验研究。 这些实验所需的强太赫兹辐射将由加州大学圣巴巴拉分校和德国德累斯顿分校的自由电子激光器产生。 该项目还将支持研究强太赫兹辐射如何改变半导体和半导体量子威尔斯的量子态和能带结构，通过太赫兹引起的近红外吸收和发射的变化来测量。 两名博士生将在半导体物理，纳米纤维，太赫兹光学，近红外和可见光频率，机械设计，低温学，电子学和实验室仪器的计算机控制以及国际合作方面接受深入而广泛的培训，为他们在国家科学和技术劳动力中的领导地位做好准备。 受资助的博士生还将指导不同的本科研究人员和高中学生实习生，激发他们对科学或工程职业的兴趣。