Abstract
The first lesson began with a reminder of the difference between universal constants, such as the quantum of action (Planck's constant) and the quantum of charge, and microscopic constants, such as the mass of the electron and proton. We also reviewed the various energy measurements : frequency of a transition between two quantum levels, electrochemical potential difference between two electron reservoirs, temperature associated with thermal fluctuations. This enabled us to compare the energy scales involved in completely macroscopic or microscopic systems, on the one hand, and those involved in mesoscopic systems, on the other. In particular, we discussed the important property of mesoscopic systems of exhibiting quantum effects even when the characteristic energy of thermal fluctuations is less than the difference between the energy levels of single-particle states, as opposed to systems ordinarily treated in quantum physics. We then presented the problem of electrical transport between two electron reservoirs separated by a region where electrons propagate in a quantum-coherent manner. The introduction of Landauer's formula allowed us to discuss the hypothesis of the independent character of transporting electrons.
