Physik  |  Kolloquien

Phys. Kolloquium: Listening to the ultrafast chat of two excited electrons—and asking them some quick physics questions

Dienstag, 23. Mai 2017
15.15 – 16.45 Uhr

R 513


Prof. Dr. Thomas Pfeifer, MPI Heidelberg

Electrons interact via the long-range Coulomb force, repel each other and feel attracted by a
nucleus that traps them inside an atom. When both electrons are in excited states, they keep
communicating repulsively, where they may agree that one of them drops back down to the
ground state, giving its energy to the other one to escape the atomic binding potential
In this talk, I will show how this very fast communication and the corresponding fundamental
dynamical processes are recorded (measured) and translated into understanding using timedomain
physics pictures. The key methods in our experimental research are the combination of
ultrafast laser/light fields (including High-Harmonic Generation and Free-Electron Lasers) and
multi-dimensional detection techniques accessing time scales of 1 femtosecond (10-15 s) and
shorter. Moreover, by asking some quick questions encoded and carried at visible frequencies
(time- and intensity-tunable laser pulses), and listening to the electrons' optical response
(spectroscopy) we learned to interpret a fundamental quantum interference process—the Fano
resonance—in the time domain, with currently emerging science and technology applications
ranging from x-ray lasing-without-inversion to frequency combs locked to nuclear resonances for
precision spectroscopy in the hard-x-ray region.