Entangling Two Individual Atoms of Different Isotopes via Rydberg Blockade.

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 Rb-87 and Rb-85 atoms confined in two single-atom optical traps separated by 3.8 mu m. The raw fidelities of the CNOT gate and entanglement are 0.73 +/- 0.01 and 0.59 +/- 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.