When light is absorbed by atoms, the electrons become excited. If the light particles, so-called photons, carry sufficient energy, the electrons can be ejected from the atom. This effect is known as photoemission and was explained by Einstein more than hundred years ago. Until now, it has been assumed that the electron start moving out of the atom immediately after the impact of the photon. This point in time can be detected and has so far been considered as coincident with the arrival time of the light pulse, i.e. with "time zero" in the interaction of light with matter.
The scientists tested the assumption, and this is what happened:
Their measurements revealed that electrons from different atomic orbitals, although excited simultaneously, leave the atom with a small but measurable time delay of about twenty attoseconds.
In the comments, provide practical illustrations of the shortest intervals of time.
Link via Popular Science | Photo: Thorsten Naeser / Max-Planck-Institute of Quantum Optics