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MO: Fachverband Molekülphysik

MO 7: Cold Molecules

MO 7.3: Talk

Tuesday, March 15, 2022, 11:00–11:15, MO-H8

Evaporation of microwave-shielded polar molecules to quantum degeneracy — Andreas Schindewolf^1,2, •Roman Bause^1,2, Xing-Yan Chen^1,2, Marcel Duda^1,2, Tijs Karman³, Immanuel Bloch^1,2,4, and Xin-Yu Luo^1,2 — ¹Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany — ²Munich Center for Quantum Science and Technology, 80799 München, Germany — ³Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands — ⁴Fakultät für Physik, Ludwig-Maximilians-Universität, 80799 München, Germany

Ultracold polar molecules offer strong dipole moments and rich internal structure, which makes them ideal building blocks for exotic quantum matter. However, even chemically nonreactive molecules have been shown to undergo inelastic two-body collisions by a mechanism that is not yet fully understood. As these collisions have so far prevented cooling to quantum degeneracy in three dimensions, overcoming them represents an important step towards full quantum control of molecules. In this work, we demonstrate evaporative cooling of a bulk gas of fermionic ²³Na⁴⁰K molecules to well below the Fermi temperature. The molecules are prevented from reaching short range with a repulsive barrier engineered by coupling rotational states with a strong microwave field, which suppresses lossy collisions. The microwave field also induces large dipole moments, leading to strong elastic collisons which enable efficient evaporation. This allows us to to cool the molecular gas down to 21 nK, which is 36% of the Fermi temperature.