A major issue of quantum electronics is to achieve interference experiments with a small controlled number of electrons. This requires the implementation of a yet never done reliable source that can inject an arbitrary number of indistinguishable electrons in a mesoscopic conductor. Here we consider an electron source based on short time voltage pulses, that delivers q quanta of charge per pulse. For most of the voltage pulses, this charge is accompagnied by a statistical number N+ of quasi-particles (holes and electrons), the total charge of which being neutral. However, for Lorentzian-shaped voltage pulses, N+ remarkably vanishes. This leads to a minimal excitation n-electron source, with a reliable number of emitted quasi-particles. In this thesis we present a first attempt to experimentally implement this n-electron source. Sub-nanosecond pulses are applied on a quantum point contact (QPC) realized in a clean two-dimensionnal electron gas of GaAs/AlGaAs heterostructure. When the single channel of the QPC is not perfectly transmitted, shot-noise occurs and reveals the excess number N+ of quasi-particles emitted by the pulses. Thus the property of the minimal excitation number of the integer Lorentzian pulses can be tested. Moreover, shot-noise gives access to the spectroscopy of the absorption and emission processes of photons that give rise to the excited quasi-particles. In our experiments, the sine, square and Lorentzian shape pulses are compared. The distinct character of the quasi-particles excitations of Lorentzian pulses is demonstrated and results are in quantitative agreement with the theoretical predictions at finite temperature.
