Weakly Flux-Tunable Superconducting Qubit

• Published in: arXiv.org
• Main Authors: Chávez-Garcia, José M, Solgun, Firat, Hertzberg, Jared B, Jinka, Oblesh, Brink, Markus, Abdo, Baleegh
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 08.03.2022
• Subjects: Anharmonicity; Collisions; Design parameters; Gates; Noise sensitivity; Physics - Quantum Physics; Physics - Superconductivity; Processors; Qubits (quantum computing); Resonance; Superconductivity; Tradeoffs
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2203.04164

Flux-tunable qubits are a useful resource for superconducting quantum processors. They can be used to perform cPhase gates, facilitate fast reset protocols, avoid qubit-frequency collisions in large processors, and enable certain fast readout schemes. However, flux-tunable qubits suffer from a trade-off between their tunability range and sensitivity to flux noise. Optimizing this trade-off is particularly important for enabling fast, high-fidelity, all-microwave cross-resonance gates in large, high-coherence processors. This is mainly because cross-resonance gates set stringent conditions on the frequency landscape of neighboring qubits, which are difficult to satisfy with non-tunable transmons due to their relatively large fabrication imprecision. To solve this problem, we realize a coherent, flux-tunable, transmon-like qubit, which exhibits a frequency tunability range as small as 43 MHz, and whose frequency, anharmonicity and tunability range are set by a few experimentally achievable design parameters. Such a weakly tunable qubit is useful for avoiding frequency collisions in a large lattice while limiting its susceptibility to flux noise.