# Preparation of a Heteronuclear Two-atom System in the 3D Motional Ground State in an Optical Tweezer

## TL;DR

This paper demonstrates the successful preparation of a heteronuclear $^{87}$Rb-$^{85}$Rb two-atom system in the 3D motional ground state within an optical tweezer, enabling advanced quantum experiments and potential applications in ultracold chemistry.

## Contribution

The first realization of a heteronuclear two-atom system in the 3D motional ground state in an optical tweezer with high ground state fidelity and species-dependent merging capability.

## Key findings

- Achieved 3D ground state probabilities of 0.91 for both atoms.
- Successfully merged two different isotopic atoms with minimal vibrational excitation.
- Observed no significant crosstalk during Raman sideband cooling.

## Abstract

We report the realization of a heteronuclear two-atom of $^{87}$Rb-$^{85}$Rb in the ground state of an optical tweezer (OT). Starting by trapping two different isotopic single atoms, a $^{87}$Rb and a $^{85}$Rb in two strongly focused and linearly polarized OT with 4 $\mu$m apart, we perform simultaneously three dimensional Raman sideband cooling for both atoms and the obtained 3D ground state probabilities of $^{87}$Rb and $^{85}$Rb are 0.91(5) and 0.91(10) respectively. There is no obvious crosstalk observed during the cooling process. We then merge them into one tweezer via a species-dependent transport, where the species-dependent potentials are made by changing the polarization of the OTs for each species from linear polarization to the desired circular polarization. The measurable increment of vibrational quantum due to merging is $0.013(1)$ for the axial dimension. This two-atom system can be used to investigate cold collisional physics, to form quantum logic gates, and to build a single heteronuclear molecule. It can also be scaled up to few-atom regime and extended to other atomic species and molecules, and thus to ultracold chemistry.