Roton Excitations in an Oblate Dipolar Quantum Gas

ORAL

Abstract

Elementary excitations leave a characteristic footprint in the fluctuations of a quantum mechanical system. We report on first signatures of radial and angular roton excitations around a droplet crystallization transition in oblate dipolar Bose-Einstein condensates by direct in situ measurements of the density fluctuations near this transition. This approach allows for a direct extraction of the static structure factor simultaneously at all momenta, which we use to identify the radial and angular excitations by the characteristic symmetries of their spatial patterns. The fluctuations peak as a function of interaction strength indicating the crystallization transition of the system. We connect the crystallization mechanism with the softening of the angular roton modes by comparing our observations to a theoretically calculated excitation spectrum. This understanding is an important step towards the realization of a dipolar supersolid in two-dimensional oblate trapping geometries.

*This work is supported by the German Research Foundation (DFG) within FOR2247 under Pf381/16-1 and Bu2247/1, Pf381/20-1, FUGG INST41/1056-1 and the QUANT:ERA collaborative project MAQS. M.G. and M.Z. acknowledge funding from the Alexander von Humboldt Foundation.

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Publication: arXiv:2102.01461

Presenters

  • Jan-Niklas Schmidt

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, University of Stuttgart
    • University of Stuttgart
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart

Authors

  • Jan-Niklas Schmidt

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, University of Stuttgart
    • University of Stuttgart
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart

  • Jens Hertkorn

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart
    • University of Stuttgart

  • Mingyang Guo

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, University of Stuttgart
    • University of Stuttgart
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart

  • Fabian Boettcher

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, University of Stuttgart
    • University of Stuttgart
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart

  • Matthias Schmidt

    • University of Stuttgart

  • Kevin Ng

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, University of Stuttgart
    • University of Stuttgart
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart

  • Sean Graham

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, University of Stuttgart
    • University of Stuttgart
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart

  • Tim Langen

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart
    • Universtiy of Stuttgart
    • Stuttgard
    • University of Stuttgart

  • Martin W Zwierlein

    • Massachusetts Institute of Technology MIT
    • MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology

  • Tilman Pfau

    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
    • 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart
    • University of Stuttgart
    • 5th Institute of Physics, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany