Listening to the ultrafast chat of excited electron pairs in atoms – and teaching them to compute in an intense laser flash

Light-Matter interaction already taught us many lessons of fundamental physics. To list only a few examples: Spectral analysis of flames, uncovering discrete atomic energy levels, and the photoelectric effect leading to the discovery of quantum mechanics, all the way to the laser principle itself along with its multitude of applications, among them quantum-optics science and technology. The Nobel Prize in Physics 2023 honored the exploration of light-matter interactions at extremely short, attosecond time intervals, opening a portal to exploring electrons in motion within atoms and molecules. In this talk, I will give an overview of some of our experiments along such explorative routes towards understanding, and control of electronic processes in atoms and molecules on ultrafast time scales. Employing intense short laser flashes(pulses) of light, the fundamental properties of atomic and molecular states can be strongly modified and returned to their natural state within a few femtoseconds. These changes can be read out by spectroscopy, similar to Fraunhofer's approach of observing dark lines characteristic to specific atoms in the solar spectrum. Our approach builds on this principle and goes beyond in the analysis of time-, and intensity-dependent spectral structures, thus gaining access to the full quantum information, amplitude and phase, of quantum-dynamical modifications of atomic and molecular excited states. Starting our journey from two electrons in Helium, giving rise to Fano resonances, we extract the fundamental mechanisms and afterwards apply them in quantum systems of increasing complexity. These experiments point towards a potential future vision: An ultrafast quantum computer based on atomic or molecular states, programmable by intense fields of light.