Quantum Interference Observed in Real Time: Extreme UV-Light Spectroscopy Technique
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Quantum interference observed in real time: Extreme UV-light spectroscopy technique:
A team headed by Prof. Dr. Frank Stienkemeier and Dr. Lukas Bruder from the Institute of Physics at the University of Freiburg has succeeded in observing in real-time ultrafast quantum interferences-in other words the oscillation patterns-of electrons which are found in the atomic shells of rare gas atoms. They managed to observe oscillations with a period of about 150 attoseconds-an attosecond is a billionth of a billionth of a second. To this end, the scientists excited rare gas atoms with specially prepared laser pulses. Then they tracked the response of the atoms with a new measurement technique that enabled them to study quantum mechanical effects in atoms and molecules at extremely high time resolution. The researchers present their results in the latest edition of Nature Communications.
[...] Stienkemeier's team has extended a technology known from the visible spectrum range, coherent pump-probe spectroscopy, into the ultra-violet range. This is the spectral range between X-ray radiation and ultra-violet light. To do this, the scientists prepared a sequence of two ultra-short laser pulses in the extreme ultra-violet range at the FERMI free electron laser in Trieste, Italy. The pulses were separated by a precisely-defined time interval and had a precisely-defined phase relationship to one another. The first pulse starts the process in the electron shell (pump-process). The second pulse probes the status of the electron shell at a later point (probe-process). By altering the time interval and the phase relationship, the researchers could reach conclusions on the temporal development in the electron shell. "The greatest challenge was to achieve precise control over the pulse properties and to isolate the weak signals," explains Andreas Wituschek, who was in charge of the experimental procedure.
Andreas Wituschek et al. Tracking attosecond electronic coherences using phase-manipulated extreme ultraviolet pulses, Nature Communications (2020). DOI: 10.1038/s41467-020-14721-2
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