SAMOP 2021 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 8: Cold Molecules
MO 8.6: Vortrag
Freitag, 24. September 2021, 12:00–12:15, H1
An open microwave resonator for trapping ultracold polar molecules — •Maximilian Löw, Fabian Salamon, Martin Ibrügger, and Martin Zeppenfeld — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching
In recent years tremendous progress has been made producing polar molecules in the ultracold regime via direct cooling methods. However, one of the main challenges remains the realization of high phase space densities.
To this end, we are designing a microwave trap as the next stage in our experiment. Working at a frequency of 50 GHz it acts as a red-detuned dipole trap on the rotational transition |J,Ka,Kc>= |211>←|110> of formaldehyde. We present the successful realisation of a high-finesse open microwave resonator to achieve trap depths above 1 mK with reasonable input power while maintaining optical access. Special focus is laid on a new type of incoupling mirror whose design was optimized using FEM simulations. It enables free-space coupling into the resonator and is designed to dissipate tens of Watts of microwave power while its absorption losses stay small. To characterize our system, we developed special measurement techniques to determine the transmission through the incoupling mirror and the finesse of the resonator. First results show we can achieve a critically coupled finesse of at least 1650 with values of up to 2000 being in reach.
The resonator we developed fulfills the requirements to be used as a microwave trap for formaldehyde allowing us to aim for the regime of quantum degeneracy using evaporative or sympathetic cooling.