Teleported CNOT Gate in a Mixed-Species Trapped-Ion System*

Scaling up quantum information processing (QIP) can be aided by distributing qubits across multiple processing zones. Universal quantum computation across such an architecture will require entangling gates between qubits in separate zones. Quantum gate teleportation achieves this, requiring only local operations within each zone, a single entangled ancilla pair split between the two zones, and classical communication. Using this protocol, we demonstrate a teleported CNOT gate between two spatially separated ⁹Be⁺ ions by means of a split entangled pair of ²⁵Mg⁺ ions and measure an entanglement fidelity in the interval (0.845, 0.872) at the 95% confidence level. Our demonstration combines many important tools for scaling trapped-ion QIP, including ion separation and shuttling, individually addressed single qubit rotations and detections, same- and mixed-species entangling gates, and real-time conditional feedforward operations.