We report an improved test of the weak equivalence principle by using a simultaneous ${}^{85}\mathrm{Rb}\text{−}{}^{87}\mathrm{Rb}$ dual-species atom interferometer. We propose and implement a four-wave double-diffraction Raman transition scheme for the interferometer, and demonstrate its ability in suppressing common-mode phase noise of Raman lasers after their frequencies and intensity ratios are optimized. The statistical uncertainty of the experimental data for Eötvös parameter $\eta$ is $0.8\times 10^{-8}$ at 3200 s. With various systematic errors corrected, the final value is $\eta =(2.8\pm 3.0)\times 10^{-8}$. The major uncertainty is attributed to the Coriolis effect.

We report on the first experimental realization of the controlled-not (cnot) quantum gate and entanglement for two individual atoms of different isotopes and demonstrate a negligible cross talk between two atom qubits. The experiment is based on a strong Rydberg blockade for ${}^{87}\mathrm{Rb}$ and ${}^{85}\mathrm{Rb}$ atoms confined in two single-atom optical traps separated by $3.8\mu \mathrm{m}$. The raw fidelities of the cnot gate and entanglement are $0.73\pm 0.01$ and $0.59\pm 0.03$, respectively, without any corrections for atom loss or trace loss. Our work has applications for simulations of many-body systems with multispecies interactions, for quantum computing, and for quantum metrology.

We demonstrate trapping a single rubidium atom in a blue detuned optical bottle beam trap. The trap was formed by a strongly focused blue detuned laser beam, which passes through a computer-generated circular π phase hologram displayed on a spatial light modulator. Single atoms were loaded from a magneto-optical trap and stored in the optical trap for several seconds.

Optically trapped mixed-species single atom arrays with arbitrary geometry are an attractive and promising platform for various applications, because tunable quantum systems with multiple components provide extra degrees of freedom for experimental control. Here, we report the first demonstration of two-dimensional $6\times 4$ dual-species atom assembly of ${}^{85}\mathrm{Rb}$ (${}^{87}\mathrm{Rb}$) atoms with a filling fraction of 0.88 (0.89). This mixed-species atomic synthesis is achieved via rearranging initially randomly distributed atoms by a sorting algorithm (heuristic heteronuclear algorithm) which is designed for bottom-up atom assembly with both user-defined geometries and two-species atom number ratios. Our fully tunable hybrid-atom systems with scalable advantages are a good starting point for high-fidelity quantum logic, many-body quantum simulation, and single molecule array formation.

As a conventional approach, optical dipole trap (ODT) arrays with linear polarization have been widely used to assemble neutral-atom qubits for building a quantum computer. However, due to the inherent scalar differential light shifts (DLS) of qubit states induced by trapping fields, the microwave-driven gates acting on single qubits suffer from errors on the order of ${10}^{-3}$. Here, we construct a DLS compensated ODT array based upon a recently developed magic-intensity trapping technique. In such a magic-intensity optical dipole trap (MI-ODT) array, the detrimental effects of DLS are efficiently mitigated so that the performance of global microwave-driven Clifford gates is significantly improved. Experimentally, we achieve an average error of $(4.7\pm 1.1)\times {10}^{-5}$ per global gate, which is characterized by randomized benchmarking in a $4\times 4$ MI-ODT array. Moreover, we experimentally study the correlation between the coherence time and gate errors in a single MI-ODT with an optimum error per gate of $(3.0\pm 0.7)\times {10}^{-5}$. Our demonstration shows that MI-ODT array is a versatile platform for building scalable quantum computers with neutral atoms.