Rostock 2019 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 13: Ultra-cold atoms (joint session A/Q)
A 13.5: Vortrag
Mittwoch, 13. März 2019, 11:30–11:45, S HS 1 Physik
Ultracold and Ultrafast: Coherent manipulation of matter-waves on femtosecond timescales — •Tobias Kroker1,2, Bernhard Ruff1,2, Juliette Simonet1,2, Klaus Sengstock1,2, Philipp Wessels1,2, and Markus Drescher1,2 — 1Zentrum für Optische Quantentechnologien (ZOQ), Luruper Chaussee 149, 22761 Hamburg — 2The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg
Ultrashort laser pulses, even far detuned from atomic resonances, can significantly modify coherent matter-waves, as the high laser intensities produce considerable AC Stark shifts.
We show that phases up to several π can be imprinted within femtoseconds, resulting in accelerations of the atomic cloud up to 109 m/s2.
The interplay between the phase gradient and atomic
interactions can lead to a stable matter wave. Numerical simulations of the 3D Gross-Pitaevskii equation are in good agreement with our experimental data.
Such high laser intensities can even give rise to a coherent
superposition between ground and excited states during the femtosecond pulse.
Ultracold atoms allow revealing this transient effect, which is not accessible using standard spectroscopy techniques, since they can be trapped in such shallow average light shifts. Accurate measurement of the trapping frequencies indeed demonstrate the transient population of the excited states.