Freiburg 2024 – scientific programme
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A: Fachverband Atomphysik
A 40: Ultra-cold Atoms, Ions and BEC V (joint session A/Q)
A 40.8: Talk
Friday, March 15, 2024, 16:15–16:30, HS 1010
Anisotropic and Non-Additive Interactions of Rydberg Impurities in Bose-Einstein Condensates — •Aileen A.T. Durst1,2, Seth T. Rittenhouse3,2, Hossein R. Sadeghpour2, and Matthew T. Eiles1 — 1Max-Planck-Institute for the Physics of Complex Systems, Germany — 2ITAMP, Harvard & Smithsonian, USA — 3United States Naval Academy, USA
The interaction between a highly electronically excited atomic impurity and surrounding BEC atoms is typically characterised by a scattering length which can rival or even surpass the average interparticle spacing. The significance of this interaction depends on the density: when the average distance between Bosons is smaller than the scattering length, the system exhibits a rich absorption spectrum which extends typical polaron physics. However, within a dense bath, the absorption spectrum consists only of a single broad Gaussian, indicating an almost classical response. The scattering length and interaction strength of a Rydberg impurity can be altered by changing the principal quantum number. Additionally, the electronic angular momentum of the impurity can be changed in order to control the nature of the interaction potential, which becomes anisotropic when the spherical symmetry is broken. In free space, this manipulation leads to the emergence of (2l+1) degenerate electronic potential energy surfaces, introducing additionally non-additive interactions. Our investigation delves into the impact of these non-additive and anisotropic interactions on the absorption spectrum of a Rydberg impurity within an ideal BEC.
Keywords: Polaron; Rydberg; Strongly interacting systems; BEC; Anisotropic interactions