Nano-optics explores optical phenomena occurring far below the diffraction limit of light. To overcome this limit, new concepts and techniques have emerged, among which the use of fast electrons—traveling at about half the speed of light—has proven uniquely powerful for probing the optical properties of nanomaterials. Our team has been a pioneer in this field, using electron energy-loss spectroscopy (EELS) and cathodoluminescence (CL) to study a wide range of excitations in solids, from phonons to excitons, with unprecedented spatial and spectral resolution. More recently, we have developed energy-gain spectroscopy (EEGS), which combines the picometer-scale spatial precision of fast electrons with the sub-µeV spectral resolution of a laser. This innovation enables the investigation of quantum-optical systems such as ultra-high-finesse optical cavities. However, a key question remains open: can we coherently study and manipulate optical states in atomic or quasi-atomic systems such as quantum dots using relativistic electrons? The aim of this internship, potentially leading to a PhD, is to explore this new regime of coherent control of artificial atoms with electron beams. The project will take place on a unique platform coupling a monochromated transmission electron microscope with a laser system and custom-designed lithographic samples, opening unprecedented perspectives in quantum nano-optics.