Balanced Coherence Times of Atomic Qubits of Different Species in a Dual 3 x 3 Magic-Intensity Optical Dipole Trap Array

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 trapping laser. Experimentally, polarization of the ODT array for Rb-85 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 Rb-87 qubits in another ODT array with fully circular polarization. Ultimately, in such a polarization-mediated MI-ODTarray, the coherence times of Rb-87 and Rb-85 qubits are, respectively, enhanced up to 891 +/- 47 ms and 943 +/- 35 ms. Moreover, we reveal that the noise of the elliptic polarization causes dephasing effect on the Rb-85 qubits but it could be efficiently mitigated by choosing the dynamical range of active polarization device. We also show that light shifts seen by qubits in an elliptically polarized MI-ODT can be more efficiently compensated due to the decrease in the ground state hyperpolarizability. It is anticipated that the novel mixed-species MI-ODT array is a versatile platform for building scalable quantum computers with neutral atoms.