Designing high-fidelity gates for neutral-atom quantum computing
"A neutral-atom system serves as a promising platform for realizing gate-based quantum computing (QC) because of its ability to coherently control several qubits in different geometries and to scale to a large number of qubits in optical lattices; however, the two-qubit entangling gate fidelity lags behind competing QC platforms such as superconducting systems and ion-traps. The aim of our work is to design gate procedures that deliver a Bell state with fidelity (F) > 0.9999, which is required for scalable QC using neutral atoms. We use the quantum-control technique of laser pulse shaping to realize robust and high-performance two-qubit Rydberg-blockade gates in the presence of realistic noise terms.
A few theoretical proposals, based on Rydberg-blockade interaction, deliver two-qubit gates with F > 0.9999, while state-of-the-art experiments only achieve F > 0.81. New robust procedures based on adiabatic and simultaneous driving of both atoms can potentially deliver high-fidelity Bell-states experimentally. I present two methods within experimentally feasible conditions, one using global optimization and the other using shortcut-to-adiabaticity, for designing the time-dependent amplitude and detuning of each Rabi pulse. We achieved F > 0.99, considering population decay of the atomic levels, by solving the Lindbladian in the Python package QuTiP. Preliminary results demonstrate that our techniques deliver high fidelity for a simplified model, with future work focussed on making the model more realistic.
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