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A: Fachverband Atomphysik
A 15: Ultra-cold atoms, ions and BEC II (joint session A/Q)
A 15.2: Vortrag
Mittwoch, 16. März 2022, 10:45–11:00, A-H2
Signatures of radial and angular rotons in a two-dimensional dipolar quantum gas — •Sean Graham1, Jan-Niklas Schmidt1, Jens Hertkorn1, Mingyang Guo1, Fabian Böttcher1, Matthias Schmidt1, Kevin Ng1, Tim Langen1, Martin Zwierlein2, and Tilman Pfau1 — 15th Institute of Physics and Center for Integrated Quantum Science and Technology IQST, University of Stuttgart, Germany — 2MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, USA
We observed signatures of radial and angular roton modes and their contribution to droplet formation in an oblate dipolar quantum gas. Roton modes have a finite momentum that can be significantly populated in dipolar quantum gases when dipole-dipole interactions are strong relative to hard-core interactions. For stronger dipole-dipole interactions the condensate will crystallize into droplets. Near this crystallization transition we extract the static structure factor from in-situ density fluctuations. We identify the presence of a radial roton by a peak at finite momentum in the radial structure factor that appears near the transition. Additional peaks are observed in the angular structure factor corresponding to the population of the angular roton mode. Finally, a comparison to simulated mode patterns from the extended Gross-Pitaevski equation shows good agreement with our results.