# Balanced Coherence Times of Mixed-Species Atomic Qubits in a Dual $3\times3$ Magic-Intensity Optical Dipole Trap Array

## TL;DR

This paper demonstrates a polarization-mediated magic-intensity optical dipole trap array that balances and enhances coherence times of mixed-species atomic qubits, advancing scalable neutral atom quantum computing.

## Contribution

It introduces a novel mixed-species magic trapping technique using polarization control to significantly improve and balance qubit coherence times.

## Key findings

- Coherence times of $^{87}$Rb and $^{85}$Rb qubits reach over 890 ms and 940 ms.
- Polarization noise causes dephasing, mitigated by shallow magic intensity.
- The platform is promising for scalable neutral atom quantum computers.

## Abstract

In this work, we construct a polarization-mediated magic-intensity (MI) optical dipole trap (ODT) array, in which the detrimental effects of light shifts on the mixed-species qubits are efficiently mitigated so that the coherence times of the mixed-species qubits are both substantially enhanced and balanced for the first time. This mixed-species magic trapping technique relies on the tunability of the coefficient of the third-order cross term and ground state hyperpolarizability, which are inherently dependent on the degree of circular polarization of the trap laser. Experimentally, polarization of the ODT array for $^{85}$Rb qubits is finely adjusted to a definite value so that its working magnetic field required for magic trapping amounts to the one required for magically trapping $^{87}$Rb qubits in another ODT array with fully circular polarization. Ultimately, in such a polarization-mediated MI-ODT array, the coherence times of $^{87}$Rb and $^{85}$Rb qubits are respectively enhanced up to 891$\pm$47 ms and 943$\pm$35 ms. Furthermore, a new source of dephasing effect is revealed, which arises from the noise of the elliptic polarization, and the reduction in corresponding dephasing effect on the $^{85}$Rb qubits is attainable by use of shallow magic intensity. It is anticipated that the novel mixed-species MI-ODT array is a versatile platform for building scalable quantum computers with neutral atoms.