Coherent manipulation of matter-waves on femtosecond timescales
ORAL
Abstract
Bridging the worlds of ultrafast physics and ultracold quantum matter opens new pathways to manipulate macroscopic wave functions on femtosecond timescales and to control the formation of ions and electrons in a quantum gas [1, 2] towards the creation of hybrid quantum systems.
The electric field of a single femtosecond laser pulse allows ultrafast phase imprinting in a Bose-Einstein condensate (BEC). The strong transient ac Stark shifts give rise to time-dependent attractive or repulsive potentials determined by the intensity profile and detuning of the laser pulse. Here we show that, even far detuned from any atomic resonances, peak accelerations exceeding 109 m/s2 can be used to engineer propagating 87Rb matter-waves with unprecedented transversal beam temperatures below 18 nK. The combination of ultracold atoms and ultrashort laser pulses as instantaneous trigger allows a precise comparison of the experimental results and the semi-classical oscillator model of the optical dipole potential. Even though its validity becomes debatable at peak intensities up to 1013 W/cm2 used in the experiment, we find that the transferred momentum is accurately described by this model and only limited by strong-field ionization. Additionally, we show that the interplay between an attractive potential and repulsive atomic interactions leads to a stable BEC with density enhancement. Simulations based on numerically solving the 3D Gross-Pitaevskii equation are in good agreement with the measurements confirming the coherent nature of the ultrafast phase imprinting.
Ultrashort laser pulses arise as a versatile tool for precise manipulation of ultracold gases regardless of the specific atomic level structure. Our experimental findings demonstrate a general scheme for engineering monoenergetic beams of atoms, particularly relevant for quantum chemistry, controlled collision experiments, and atom lithography.
The electric field of a single femtosecond laser pulse allows ultrafast phase imprinting in a Bose-Einstein condensate (BEC). The strong transient ac Stark shifts give rise to time-dependent attractive or repulsive potentials determined by the intensity profile and detuning of the laser pulse. Here we show that, even far detuned from any atomic resonances, peak accelerations exceeding 109 m/s2 can be used to engineer propagating 87Rb matter-waves with unprecedented transversal beam temperatures below 18 nK. The combination of ultracold atoms and ultrashort laser pulses as instantaneous trigger allows a precise comparison of the experimental results and the semi-classical oscillator model of the optical dipole potential. Even though its validity becomes debatable at peak intensities up to 1013 W/cm2 used in the experiment, we find that the transferred momentum is accurately described by this model and only limited by strong-field ionization. Additionally, we show that the interplay between an attractive potential and repulsive atomic interactions leads to a stable BEC with density enhancement. Simulations based on numerically solving the 3D Gross-Pitaevskii equation are in good agreement with the measurements confirming the coherent nature of the ultrafast phase imprinting.
Ultrashort laser pulses arise as a versatile tool for precise manipulation of ultracold gases regardless of the specific atomic level structure. Our experimental findings demonstrate a general scheme for engineering monoenergetic beams of atoms, particularly relevant for quantum chemistry, controlled collision experiments, and atom lithography.
*This work is funded by the Cluster of Excellence "CUI: Advanced Imaging of Matter" of the Deutsche Forschungsgemeinschaft (DFG) - EXC 2056 - project ID 390715994 as well as by the Cluster of Excellence "The Hamburg Centre for Ultrafast Imaging" of the DFG - EXC 1074 - project ID 194651731.
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Publication: [1] T. Kroker, M. Großmann, K. Sengstock, M. Drescher, P. Wessels-Staarmann, and J. Simonet, "Ultrafast electron cooling in an expanding ultracold plasma", Nat. Commun. 12, 596 (2021).
[2] P. Wessels, B. Ruff, T. Kroker, A. K. Kazansky, N. M. Kabachnik, K. Sengstock, M. Drescher, and J. Simonet, "Absolute strong-field ionization probabilities of ultracold rubidium atoms", Commun. Phys. 1, 32 (2018).
Presenters
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Philipp Wessels-Staarmann
- The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany