Quantum control of ion-atom collisions beyond the ultracold regime

TL;DR

This paper demonstrates quantum control of ion-atom collisions beyond ultracold temperatures, revealing persistent quantum interference effects and predicting Feshbach resonances at moderate magnetic fields and higher temperatures.

Contribution

It provides a comprehensive theoretical model validated by experiments, extending quantum control techniques to warmer ion-atom collision regimes.

Findings

Quantum interference effects persist beyond ultracold regimes.

Identification of Feshbach resonances at moderate magnetic fields.

Collision rates show strong state and mass dependence.

Abstract

Tunable scattering resonances are crucial for controlling atomic and molecular systems. However, their use has so far been limited to ultracold temperatures. These conditions remain hard to achieve for most hybrid trapped ion-atom systems -- a prospective platform for quantum technologies and fundamental research. Here we measure inelastic collision probabilities for ${\text{Sr}^++\text{Rb}}$ and use them to calibrate a comprehensive theoretical model of ion-atom collisions. Our theoretical results, compared with experimental observations, confirm that quantum interference effects persist to the multiple-partial-wave regime, leading to the pronounced state and mass dependence of the collision rates. Using our model, we go beyond interference and identify a rich spectrum of Feshbach resonances at moderate magnetic fields with the Rb atom in its lower ($f=1$) hyperfine state, which persist at temperatures as high as 1 mK. Future observation of these predicted resonances should allow precise control of the short-range dynamics in ${\text{Sr}^+}+{\text{Rb}}$ collisions under unprecedentedly warm conditions.