Model for two-body collisions between ultracold dipolar molecules around a Forster resonance in an electric field

We propose a one-channel, simple model to describe the dynamics of ultracold dipolar molecules around a Forster 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 us 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 behavior of the rate coefficients observed experimentally and predicted theoretically [K. Matsuda, L. De Marco, J.-R. Li, W. G. Tobias, G. Valtolina, G. Quemener, and J. Ye, Science 370, 1324 (2020); J.-R. Li, W. G. Tobias, K. Matsuda, C. Miller, G. Valtolina, L. D. Marco, R. R. W. Wang, L. Lassabliere, G. Quemener, J. L. Bohn, and J. Ye, 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.

Automated summary

Researchers propose a simple model to describe the dynamics of ultracold dipolar molecules around a Forster resonance. The model captures the quantum physical mechanism by describing the relative distance and angular approach of the molecules on a unique energy surface. The model successfully reproduces the behavior of rate coefficients observed experimentally and predicted theoretically.