Rotational vdW interaction between ultracold polar molecules

The “rotational van der Waals” interaction is the dominant interaction between polar molecules (with some exceptions, and without external fields). We show that when two molecules are in states that differ by more than one rotational quantum, this interaction is repulsive [1]. These repulsive interactions lead to applications in quantum simulation and impurity physics with ultracold polar molecules without losses due to chemical reactions. Another application is a scheme for determinstic loading of laser-cooled molecules into optical tweezer arrays [2].

[1] Walraven and Karman, arXiv:2401.05958

[2] Walraven, Tarbutt, and Karman, arXiv:2401.06028