Flip-chip Fluxonium for Coherent Analog Quantum Computing

Analog quantum architectures impose stringent specifications on superconducting qubit systems: very long coherence times, strong connectivity, and fast, high-fidelity readout. Fluxonium qubits offer a promising route forward thanks to their low transition frequencies (0.1-1 GHz), large loop inductances, and high anharmonicity, which help suppress dielectric and flux noise. Recent experimental work has achieved coherence times approaching 1.5 milliseconds [1], and readout fidelities exceeding 90% [2].

In this talk, we present Qilimanjaro’s latest developments towards an analog quantum processor based on fluxonium qubits implemented in a flip-chip architecture. The platform is conceived to operate primarily in the analog regime, enabling coherent time evolution driven by engineered Hamiltonians, while still supporting digital-style control when required. We will present the device architecture, key design advances, and experimental results, highlighting the implementation concept, crosstalk calibration methods, and single- and multi-qubit performance.

[1] Somoroff et al., Phys. Rev. Lett. 130, 267001 (2023)

[2] Ding et al., Phys. Rev. X 13, 031035 (2024)