# Thermal Atom-Ion Collisions in K-Yb$^{+}$ Hybrid System

## TL;DR

This study experimentally investigates atom-ion collisions in a K-Yb$^{+}$ hybrid system, measuring various collisional rate coefficients at thermal temperatures, highlighting the low charge-exchange rate and high spin-exchange rate relevant for quantum technologies.

## Contribution

First experimental determination of collisional rate coefficients in a thermal K-Yb$^{+}$ system, demonstrating advantages for quantum applications.

## Key findings

- Charge-exchange rate coefficients are very low, favoring sympathetic cooling.
- Spin-exchange rate coefficients are relatively high, beneficial for quantum information.
- Upper bounds for spin-destruction rates were established.

## Abstract

We present experimental studies of atom-ion collisions using buffer-gas cooled, trapped ytterbium (Yb$^+$) ions immersed in potassium (K) vapor. The range of the collisional temperature is on the order of several hundred kelvin (thermal regime). We have determined various collisional rate coefficients of the Yb$^+$ ion per K-atom number density. We find the upper bounds of charge-exchange rate coefficients $\kappa_{\rm ce}$ to be $(12.7\pm1.6)\times10^{-14}$ cm$^3$s$^{-1}$ for K-$^{171}$Yb$^+$ and $(5.3\pm0.7)\times10^{-14}$ cm$^3$s$^{-1}$ for K-$^{172}$Yb$^+$. For both isotopes, the spin-destruction rate coefficient $\kappa_{\rm sd}$ has an upper bound at $(1.46\pm0.77)\times10^{-9}$ cm$^3$s$^{-1}$. The spin-exchange rate coefficient $\kappa_{\rm se}$ is measured to be $(1.64\pm0.51)\times10^{-9}$ cm$^3$s$^{-1}$. The relatively low charge-exchange rate reported here demonstrates the advantage of using K atoms to sympathetically cool Yb$^+$ ions, and the relatively high spin-exchange rate may benefit research work in quantum metrology and quantum information processing on an atom-ion platform using K atoms and Yb$^+$ ions.