A crystalline attoclock: Ultrafast motion of free electrons in solids tracked to within attoseconds

From experience, driving through the city center takes longer than covering the same distance on an open country road. After all, you will encounter a lot of other road users, red lights, road works and traffic jams in the city center. Conversely, if you want to find out how busy a road is without having to join the traffic, you can measure the time it takes cars to travel a certain distance. This is precisely how traffic obstructions are identified by modern navigation systems. In the microcosm, this concept is maintained. When electrons (the smallest possible charge carriers) move through solids, they can interact with other electrons, changing their dynamics. However, due to the tiny mass of the electrons, the relevant processes take place unimaginably fast and they follow the intriguing laws of quantum physics rather than classical mechanics.