Dipolar molecules finally truly under control!

Ultracold polar molecules offer strong electric dipole moments and a rich internal structure, which makes them ideal building blocks to explore exotic quantum matter, to implement novel quantum information schemes, or to test fundamental symmetries of nature. However, until recently, collisional loss at short range, even for nominally nonreactive molecules, has strongly limited the use of interacting molecules and prevented evaporation of the molecules to the quantum degenerate regime. We now demonstrate that coupling rotational states with a blue-detuned circularly polarized microwave can not only shield the molecules from reaching the lossy regime at short range, but simultaneously provides strong tunable dipolar interactions. We make use of this so called 'microwave shielding' to evaporate fermionic NaK molecules reaching a record low temperature of 21 nK, corresponding to 0.36 times the Fermi temperature.

arXiv:2201.05143