Model for two-body collisions between ultracold dipolar molecules around a F\"orster resonance in an electric field

TL;DR

This paper introduces a simple one-channel model to describe ultracold dipolar molecule collisions near a F"orster resonance, capturing key physics and matching experimental and theoretical results, with potential for studying more complex systems.

Contribution

The paper presents a novel, simplified model that effectively describes ultracold dipolar molecule collisions around a F"orster resonance, reducing computational complexity.

Findings

Model reproduces experimental rate coefficients

Captures the physics of dipole induction and interaction

Predicts collisional shielding effects

Abstract

We propose a one-channel, simple model to describe the dynamics of ultracold dipolar molecules around a F\"orster resonance. Slightly above a specific electric field, a collisional shielding can take place, suppressing the molecular losses in a gas. The overall description of the quantum physical mechanism comes back to the dynamics on a unique energy surface, which depends on the relative distance and angular approach of the molecules. This surface enables to interpret how the dipole moments of the molecules are induced and interlocked by the electric field and the dipole-dipole interaction during the process, especially when the shielding is triggered. Averaging the relative angular motion over a unique partial wave (the lowest one when the ultracold regime is reached), the model reproduces well the behaviour of the rate coefficients observed experimentally and predicted theoretically [Matsuda et al., Science 370, 1324 (2020); Li et al., Nat. Phys. 17, 1144 (2021)]. This economic model encapsulates the main physics of the quantum process. Therefore, it can be used as an alternative to a full quantum dynamical treatment and is promising for future studies of collisions involving more bodies.