Resonant collisional shielding of reactive molecules using electric fields

TL;DR

This paper demonstrates how external electric fields can resonantly control and suppress chemical reactions in ultracold polar molecules by tuning collision channels, enabling long-lived molecular samples.

Contribution

It introduces a method to resonantly modulate and shield reactive molecules using electric fields, achieving significant reaction rate suppression.

Findings

Reaction rates modulated by three orders of magnitude.

Electric field tuning induces resonant dipolar interactions.

Achieved long-lived polar molecule samples in large electric fields.

Abstract

Full control of molecular interactions, including reactive losses, would open new frontiers in quantum science. Here, we demonstrate extreme tunability of chemical reaction rates by using an external electric field to shift excited collision channels of ultracold molecules into degeneracy with the initial collision channel. In this situation, resonant dipolar interactions mix the channels at long range, dramatically altering the intermolecular potential. We prepare fermionic potassium-rubidium (KRb) molecules in their first excited rotational state and observe a three orders-of-magnitude modulation of the chemical reaction rate as we tune the electric field strength by a few percent across resonance. In a quasi-two-dimensional geometry, we accurately determine the contributions from the three lowest angular momentum projections of the collisions. Using the resonant features, we shield the molecules from loss and suppress the reaction rate by up to an order of magnitude below the background value, realizing a long-lived sample of polar molecules in large electric fields.