Fast High-Fidelity Gates for Galvanically-Coupled Fluxonium Qubits Using Strong Flux Modulation
Daniel Weiss, Helin Zhang, Chunyang Ding +3 more
Long coherence times, large anharmonicity, and robust charge-noise insensitivity render fluxonium qubits an interesting alternative to transmons.Recent experiments have demonstrated record coherence times for low-frequency fluxonium qubits.Here, we propose a galvanic coupling scheme with flux-tunable XX coupling.To implement a high-fidelity entangling √ iSWAP gate, we modulate the strength of this coupling and devise variable-time identity gates to synchronize required single-qubit operations.Both types of gates are implemented using strong ac flux drives, lasting for only a few drive periods.We employ a theoretical framework capable of capturing qubit dynamics beyond the rotating-wave approximation as required for such strong drives.We predict an open-system fidelity of F > 0.999 for the √ iSWAP gate under realistic conditions.
arXiv:2207.03971•PRX Quantum•Dec 27, 2022•27 citations