Among the technologies that hold promise for quantum computing, trapped atomic ions offer outstanding coherence and operation fidelity, but cannot easily compete with solid-state systems in terms of logic speed—especially for the two-qubit operations that are necessary to generate entanglement. Here, David Lucas and collaborators use amplitude-shaped laser pulses to drive trapped calcium ions in a way that ensures gate operation that is robust against optical phase fluctuations. They generate entanglement with 99.8% fidelity and achieve a gate duration of less than two microseconds. They also demonstrate faster operation of around 500 nanoseconds, albeit with lower gate fidelity. This experimental work addresses a substantial limiting factor for trapped-ion technology, and the authors expect their method to contribute to the scaling up of logic operations to larger numbers of qubits.
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