SAMOP 2021 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 16: Ultra-cold atoms, ions, and BEC (joint session A/Q)
A 16.12: Poster
Mittwoch, 22. September 2021, 16:30–18:30, P
All-optical production of K-39 BECs utilizing tunable interactions — •Alexander Herbst, Henning Albers, Sebastian Bode, Knut Stolzenberg, Ernst Rasel, and Dennis Schlippert — Institute of Quantum Optics, Leibniz University Hannover, Welfengarten 1, 30167 Hannover
The all-optical production of potassium-39 BECs is of large interest for the field of guided atom interferometry and its application for quantum inertial sensors. Contrary to other setups and atomic species this combination allows for the use of small external magnetic fields to control atomic interactions for the suppression of dephasing effects. However, the negative background scattering length and the narrow hyperfine splitting of potassium-39 pose a major experimental challenge.
We report on the loading of a crossed optical dipole trap at 2 um wavelength and the subsequent generation of a BEC. By using a gray molasses technique on the D1 line we are able to directly load the trap without the need for magnetic trapping as an intermediate step.
For evaporation we utilize time-averaged optical potentials to control the trap frequencies in combination with Feshbach resonances to change the atomic scattering length to positive values. We realize BECs of up to 2·105 atoms after a 4 second long evaporation ramp and more than 5·104 atoms after less than 1 second. We discuss our experimental sequence, the current limitations of our setup and the perspectives for producing BECs of higher atom number with the fast ramp.