Control of reactive collisions by quantum interference

TL;DR

This paper demonstrates magnetic control of reactive collisions in ultracold Na-NaLi mixtures by tuning quantum interference, significantly altering loss rates and controlling chemical reactions at ultracold temperatures.

Contribution

It introduces a method to control reactive scattering via quantum interference using Feshbach resonances, achieving a dynamic range of loss rate manipulation.

Findings

Loss rate varied by over 100 times using magnetic fields.

Reactive loss probability was reduced to about 4% in a fully spin-polarized state.

Quantum interference effects were explained with an optical Fabry-Perot resonator analogy.

Abstract

In this study, we achieved magnetic control of reactive scattering in an ultracold mixture of $^{23}$Na atoms and $^{23}$Na$^{6}$Li molecules. In most molecular collisions, particles react or are lost near short range with unity probability, leading to the so-called universal rate. By contrast, the Na{+}NaLi system was shown to have only $\sim4\%$ loss probability in a fully spin-polarized state. By controlling the phase of the scattering wave function via a Feshbach resonance, we modified the loss rate by more than a factor of $100$, from far below to far above the universal limit. The results are explained in analogy with an optical Fabry-Perot resonator by interference of reflections at short and long range. Our work demonstrates quantum control of chemistry by magnetic fields with the full dynamic range predicted by our models.