Kang Feng | Searcharxiv

arXiv2026

Ro-vibrational van der Waals interaction between ultracold polar molecules

We describe the ro-vibrational van der Waals interaction between ultracold polar molecules. This interaction is strong, leading to fast elastic collisions and orders of magnitude suppression of collisional loss. This enables evaporative cooling of Fermi mixtures of molecules in different ro-vibrational states, without active shielding by applying external fields. The scheme is compatible with microwave shielding, where it enables controlled state dependent interactions, opening up new opportunities for quantum simulation and impurity physics. The interaction can also be used to stabilize fermionic molecules in optical lattices, to control interactions in synthetic dimensions, for enhanced tweezer loading, and direct infrared shielding.

cond-mat.quant-gas↗

arXiv2026

Deterministic loading of molecular arrays by microwave-assisted collisions

Molecular tweezer arrays offer great prospects for quantum simulation, sensing, and computing, and would benefit from methods that enhance loading efficiency. Whereas light-assisted collisions underpin enhanced loading methods for atomic tweezer arrays, this approach cannot be directly extended to molecular arrays due to collisional loss. We show how this collisional loss can be suppressed by shelving molecules in rotationally or vibrationally excited states, so that a shelved molecule interacts with a newly loaded molecule through a repulsive van der Waals interaction. By introducing microwave assisted collisions, we show how to control the final states and the energy released in a collision between a pair of molecules. Following this controlled collision, one of the two molecules can be ejected, and we explore several strategies for ensuring deterministic ejection. Our schemes rely on currently available techniques for laser-coolable molecules, and we predict achievable filling fractions up to 96%, paving the way for scalable molecular arrays.

physics.atom-ph↗