Tileable Fluxonium Architecture with Ultrafast Inductive Single-Qubit Control Part 2: Experiment

The superconducting fluxonium qubit offers millisecond-scale coherence and high-fidelity single- and two-qubit operations. A key advantage of fluxonium is its rich structure of matrix elements. At the half-flux sweet spot, the phase matrix element between the 0 and 1 states is significantly larger than the charge matrix element, and it is the dominant contributor among all phase transitions at this flux-insensitive point. This naturally enables fast qubit rotations driven through inductive coupling at the sweet spot. We propose a tileable two-dimensional architecture for fluxonium-based quantum processors that employs exclusively inductive coupling. Leveraging the strong 0–1 phase matrix element, we further demonstrate that nanosecond scale single-qubit gates are achievable, while unwanted leakage to non-computational states is suppressed. In this ultrafast control regime, we analyze gate errors arising from effects such as counter-rotating terms and state leakage.