Electron motion, controlled on a mesoscopic scale – in nanometre-scale circuits – constitutes the basis for modern information technologies. Rendering electronics more powerful means ever faster control of currents on ever smaller scales. Microelectronics therefore naturally and inexorably evolves towards atomic-scale charge transport control, i.e. exploitation of electron motion in microscopic systems where quantum effects come to the fore and electron correlations increasingly affect response to external influence. Advancement of modern electronics towards its ultimate frontier: the electronic time scale, i.e. information processing at light frequencies, will have to rely on insight into atomic-scale electron dynamics.

The motion of excited electrons in molecules is the fundamental process behind chemical reactions, which – in turn – are crucial to synthesizing new materials, chemicals, drugs, and constitute key processes for the modern chemical and pharmaceutical industry. The interaction of the electrons bound to complex molecules forming our body with medical agents of all kinds including the molecules of a drug, the energetic particles (x-ray photons, protons, ions) bombarding the human body in radiation/particle theraphies forms the basis of medical treatments.

Electrons accelerated to velocities approaching the speed of light play a central role in producing medical x-rays and – if accelerated and steered by light – may lead to compact x-ray, proton and ion beams of improved quality for advanced diagnosis and theraphy. Detailed insight into the atomic-scale motion of electrons and gaining the ability to control electrons bound to atoms, molecules, nanostructures, as well as the trajectories of high-energy (free) electrons will help understand the fundamental physical processes behind the emergence of biological malfunction and find ways of curing it and be instrumental in developing advanced tools for medical diagnosis and theraphy.