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

点击翻译按钮获取中文摘要

****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.