CNOT gates for fluxonium qubits via selective darkening of transitions

Abstract

We analyze the cross-resonance effect for fluxonium circuits and investigate a two-qubit gate scheme based on selective darkening of a transition. In this approach, two microwave pulses at the frequency of the target qubit are applied simultaneously with a proper ratio between their amplitudes to achieve a controlled-NOT operation. We study in detail coherent gate dynamics and calculate gate error. With nonunitary effects accounted for, we demonstrate that gate error below $10^{-4}$ is possible for realistic hardware parameters. This number is facilitated by long coherence times of computational transitions and strong anharmonicity of fluxoniums, which easily prevents excitation to higher excited states during the gate microwave drive.

arXiv comment13 pages, 5 figures; published version

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• High coherence fluxonium manufactured with a wafer-scale uniformity process
• Impact of Josephson junction array modes on fluxonium readout
• Single-Qubit Gates Beyond the Rotating-Wave Approximation for Strongly Anharmonic Low-Frequency Qubits
• Cross-resonance control of an oscillator with an auxiliary fluxonium qubit
• Proposal for erasure conversion in integer fluxonium qubits