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MON: Monday Contributed Sessions

MON 23: Poster Session: Fundamental Aspects and Model Systems

MON 23.20: Poster

Monday, September 8, 2025, 18:30–20:30, ZHG Foyer 1. OG

Floquet-Engineering of Feshbach Resonances in Ultracold Lithium Gases — •Louisa Marie Kienesberger, Alexander Guthmann, Felix Lang, and Artur Widera — Physics Department and Research Center OPTIMAS, University of Kaiserslautern

Magnetic Feshbach resonances are a key tool for tuning interactions in ultracold atomic systems. In our recent work [1], we demonstrate that periodic modulation of the magnetic field enables the creation of Floquet-Feshbach resonances in a two-component gas of fermionic lithium-6, providing dynamic control over resonance positions.

We experimentally map out the structure of Floquet-dressed scattering states and confirm the theoretical predictions for their positions and widths. Our observations include clear signatures of higher-order resonances, revealing a rich spectrum of interaction control not accessible via static fields alone. Additionally, we show that inelastic atom losses can be strongly suppressed by introducing a second modulation frequency at exactly the second harmonic.

In conclusion, Floquet-Engineering of Feshbach resonances opens new pathways for precise control of scattering in ultracold gases. As a prominent application, it enables the realization of Bound States in the Continuum (BICs) through interference at avoided crossings between Floquet-Feshbach resonances, which will be discussed in a separate talk.

[1] A. Guthmann, F. Lang, L. M. Kienesberger, S. Barbosa, A. Widera , Floquet-Engineering of Feshbach Resonances in Ultracold Gases, arXiv 2503.05454 (2025).

Keywords: Feshbach resonance; Floquet; Cold atoms; Avoided crossing; Bound state in the continuum