Noise, inelastic processes, and coherence in atomic-scale and molecular junctions

****技术摘要****量子相干性的命运和耗散机制在纳米尺度上具有基本的科学兴趣，并与纳米电子技术具有潜在的相关性。该项目将使用射频噪声测量和敏感的电子传输技术来检查原子和分子尺度的结被驱动出平衡。非平衡噪声与偏置和器件温度的标度可以确定驱动电子的有效温度。在包含未配对局域自旋的结中，噪声测量将探测近藤物理，这是局域自旋与传导电子之间量子纠缠的结果。测量电导波动的偏置和温度依赖关系将允许估计这些纳米结构中电子的量子相干时间，甚至接近室温。这些实验将为两名博士生提供先进制造和测量技能（与高科技行业相关）的优秀研究培训。结果将通过博客和与当地博物馆的互动传播给公众和K12学生。****非技术摘要****对于任何使用过烤面包机的人来说都很熟悉，当电流流过宏观电线时，运动电子携带的能量以热的形式结束，而量子力学的反直觉物理似乎与此无关。然而，当电流通过单个原子或分子时，热量产生的方式和量子效应（在这种尺度上控制化学和物理）的作用就不那么透明了。在这个项目中，两名博士生将制作原子尺度的结，并使用电流及其波动作为时间和电压函数的敏感测量来“测量电子的温度”，并观察量子力学对导电的影响。理解这些尺度上的加热和量子效应与下一代纳米电子技术的发展有关。在这一领域接受教育和培训的学生将为高科技行业或研究工作做好准备，PI将通过博客和与当地博物馆的互动向公众和K12学生传播结果。

****Technical Abstract****The fate of quantum coherence and the mechanisms of dissipation at the nanoscale are of fundamental scientific interest and have potential relevance to nanoelectronic technologies. This project will use radio frequency noise measurements and sensitive electronic transport techniques to examine atomic and molecular-scale junctions driven out of equilibrium. The scaling of nonequilibrium noise with bias and device temperature allows determination of the effective temperature of the driven electrons. In junctions containing unpaired localized spins, noise measurements will probe Kondo physics, a consequence of quantum entanglement between the local spin and those of the conduction electrons. Measurements of the bias and temperature dependence of conductance fluctuations will allow the estimation of the quantum coherence time for electrons in these nanostructures even near room temperature. These experiments will provide outstanding research training in advanced fabrication and measurement skills (relevant for high technology industry) for two PhD students. Results will be disseminated to the general public and K12 students through blogging and interactions with local museums.****Non-Technical Abstract****Familiar to anyone who has ever used a toaster, when electric current flows through a macroscopic wire, energy carried by the moving electrons ends up in the form of heat, and the counterintuitive physics of quantum mechanics does not seem relevant. However, when the current passes through a single atom or molecule, the way that heat gets generated and the role of quantum effects (that govern chemistry and physics at such scales) are much less transparent. In this project two doctoral students will make atomic-scale junctions and use sensitive measurements of the current and its fluctuations as a function of time and voltage to "take the temperature" of the electrons, and to see the consequences of quantum mechanics on electrical conduction. Understanding heating and quantum effects at these scales is relevant to the development of next-generation nanoelectronics technologies. Students educated and trained in this area will be well positioned for jobs in high tech industry or research, and the PI will disseminate results to the general public and K12 students through blogging and interactions with local museums.