We demonstrate the experimental realization of a two-qubit MÃ¸lmerâ€“SÃ¸rensen gate on a magnetic field-insensitive hyperfine transition in 9Be+ ions using microwave near-fields emitted by a single microwave conductor embedded in a surface-electrode ion trap. The design of the conductor was optimized to produce a high oscillating magnetic field gradient at the ion position. The measured gate fidelity is determined to be 98.2â€‰Â±â€‰1.2% and is limited by technical imperfections, as is confirmed by a comprehensive numerical error analysis. The conductor design can potentially simplify the implementation of multi-qubit gates and represents a self-contained, scalable module for entangling gates within the quantum CCD architecture for an ion-trap quantum computer.
Following the proposal by Cirac et al.,1 trapped atomic ions have shown to be a promising and pioneering platform for implementing elements of quantum information processing (QIP).2,3 Qubits are encoded in the internal states of individual ions, and shared motional modes are used as a “quantum bus” for multi-qubit operations. Toward a large-scale universal quantum processor based on trapped-ion qubits, the “Quantum Charge-Coupled Device” (QCCD)4,5 is considered as a possible scalable hardware implementation. It relies on microfabricated multi-zone ion-trap arrays, in which quantum information is processed in dedicated zones interconnected via ion transport.