Flip-Chip Packaging of Fluxonium Qubits

The strong anharmonicity and high coherence times inherent to fluxonium superconducting circuits are desirable for implementing quantum information processors [1]. To date, coherence times in excess of 1 ms and both single- and two-qubit gate fidelities above 99.99% and 99%, respectively, have been demonstrated with fluxonium qubits [2,3]. In this talk, we report novel work on fluxoniums embedded in a multi-chip module (MCM), implementing a 2.5D architecture, where a classical control and readout chip is bump-bonded to the quantum chip. We show that this configuration does not degrade the fluxonium qubit performance, paving the way for scaling fluxonium-based quantum processors.

[1] Nguyen et al. Phys. Rev. X 9, 041041 (2019)

[2] Somoroff et al. arXiv:2103.08578 (2021)

[3] Ficheux et al. Phys. Rev. X 11, 021026 (2021)