High frequency, non-gaussian current fluctuations in mesocopic conductors / Fluctuations de courant non-gaussiennes et à haute fréquence dans les conducteurs mésosocopiques

微电子工业的发展使制造亚微米级元件成为可能。在这样的尺度下，电流所遵循的规律与通常在宏观世界中有效的规律不同。人们已经进行了许多实验来测量这种结构中的平均电流，特别是在非常低的温度下，在那里电的不寻常行为更明显。更微妙，但也更困难的是测量电流的波动，通常被称为“噪声”。电路中噪声的测量才刚刚开始，但它们可能为纳米结构的传导机制提供宝贵的信息。本课程旨在从三个方面加强我们对当前波动的认识：

Progress of the industry of micro-electronics have made possible the fabrication of components of submicron size. At that scale, the laws obeyed by the electrical current differ from the usual ones, valid in the macroscopic world. Many experiments have been performed to measure the average current in such structures, in particular at very low temperature, where unusual behavior of electricity is more visible. More subtle, but much more difficult are the measurements of the fluctuations of the current, usually nicknamed "noise". Measurements of noise in circuits are only at their beginning, but they may offer precious information on the conduction mechanisms in nanostructures. This program aims at strengthen our knowledge of current fluctuations in three directions: 1) the study of non-Gaussian noise. In a macroscopic sample, noise results from a number of independent processes, which causes current fluctuations to be described by the Gauss law, the law that describes most of random phenomena. Studying the non-Gaussian part of the noise is precisely looking at what differs from the usual laws. 2) the study of noise at high frequency. By being able to measure very fast current fluctuations, one can gain access to the characteristic time scales of electron transport, such as the time it takes for the electrons to exchange energy with their surroundings. 3) the study of temperature fluctuations. When a system is small enough, its temperature is no longer well defined, it fluctuates in time. The measurement of these fluctuations reveals how thermal processes occur in nanostructures. In addition to its interest for the advance of knowledge, this work will offer new tools to the study of novel materials and new ways to characterize components in the industry of micro-electronics.