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THU: Thursday Contributed Sessions

THU 4: Precise Quantum Molecules: Contributed Session to Symposium

THU 4.1: Talk

Thursday, September 11, 2025, 14:15–14:30, ZHG004

Floquet-Engineering of Bound States in the Continuum — •Alexander Guthmann, Louisa Marie Kienesberger, Felix Lang, and Artur Widera — Physics Department and Research Center OPTIMAS, University of Kaiserslautern-Landau

Scattering resonances play a pivotal role in quantum phenomena, from nuclear reactions to ultracold atomic collisions. Our recent work has demonstrated that periodic modulation of the magnetic field can be used to induce Floquet-Feshbach resonances in a two-component gas of fermionic lithium-6 [1], enabling precise control over resonance positions and suppression of inelastic losses.

This talk will focus on a new application of this technique: the realization of Bound States in the Continuum (BICs) through interference at an avoided crossing between two Floquet-engineered resonances. BICs are exotic quantum states that remain localized despite existing within the energy continuum of scattering states. As first predicted by Friedrich and Wintgen [2], such states can emerge through destructive interference at an avoided crossing of two resonances. While BICs have been realized in photonic and acoustic platforms, their observation in a true molecular dimer system has remained a longstanding challenge.
[1] A. Guthmann, F. Lang, L. M. Kienesberger, S. Barbosa, A. Widera, arXiv 2503.05454 (2025).
[2] H. Friedrich and D. Wintgen, Phys. Rev. A 32, 3231 (1985).

Keywords: Feshbach; Floquet; Bound states in the continuum; Cold atoms; Avoided Crossing