Reactive collisions of polar molecules in quasi-two-dimensional traps

TL;DR

This study explores how polar molecules collide in quasi-two-dimensional traps under an external electric field, revealing universal and nonuniversal collision behaviors influenced by quantum-defect parameters and dipole moments.

Contribution

It introduces a quantum-defect model for polar molecule collisions in quasi-2D traps, highlighting the effects of short-range reaction probabilities and dipole moments on collision rates.

Findings

Universal collision rates near unity reaction probability due to quantum reflection.

Trap-induced shape resonances appear at low reaction probabilities.

High dipole moments lead to damping of reactive collisions, stabilizing ultracold gases.

Abstract

We investigate collisions of polar molecules in quasi-2D traps in the presence of an external electric field perpendicular to the collision plane. We use the quantum-defect model characterized by two dimensionless parameters: $y$ and $s$. The first of them is related to the probability of the reaction at short distances, whereas the latter one defines the wave function phase at short distances. For $y$ close to unity we obtain universal collision rates determined by the quantum reflection process from the long-range part of the interaction potential that depends only on the van der Waals coefficient, dipole-dipole interaction and the trap frequency. For small short-range reaction probabilities collision rates are highly nonuniversal and trap induced shape resonances are visible. For high dipole moments we observe the damping of reactive collisions, which can stabilize the ultracold gas of polar molecules. The calculations were performed with help of multichannel wave funcion propagation by imposing short-range boundary condition derived from the quantum-defect model.