Formation of niobium hydride precipitates in superconducting qubits
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- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
- Instituto Politecnico Nacional (IPN), Mexico City (Mexico). Centro de Investigacion y de Estudios Avanzados (CINVESTAV)
- Rigetti Computing, Berkeley, CA (United States)
- European Synchrotron Radiation Facility (ESRF), Grenoble (France); Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblando (Spain)
We report evidence for the formation of niobium hydride phase within niobium films on silicon substrates in superconducting qubits fabricated at Rigetti Computing. For this study, we combined complementary techniques—including room-temperature and cryogenic atomic force microscopy (AFM), synchrotron x-ray diffraction, and time-of-flight secondary ion mass spectroscopy (ToF-SIMS)—to directly reveal the existence of niobium hydride precipitates on the surface of superconducting qubits. Upon cryogenic cooling, we observed variation in the size and morphology of the hydrides, ranging from small (∼5 nm) irregular shapes to large (∼10–100 nm) domains within the Nb grains, which were fully converted to niobium hydrides. Since niobium hydrides are nonsuperconducting and can easily change in size and location upon different cooldowns to cryogenic temperature, our finding highlights a previously unknown source of decoherence in superconducting qubits. This contributes to quasiparticle losses, offering a potential explanation for changes in qubit performance upon cooldowns. Finally, by leveraging the RF performance of a 3D bulk Nb resonator, we quantify RF dissipation in a superconducting qubit caused by hydrogen concentration variation, and propose a practical engineering pathway to mitigate the formation of Nb hydrides for superconducting qubit applications.
- Research Organization:
- Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE Office of Science (SC), High Energy Physics (HEP)
- Grant/Contract Number:
- 89243024CSC000002
- OSTI ID:
- 3012300
- Report Number(s):
- FERMILAB-PUB--25-0589-TD; oai:inspirehep.net:2962426; arXiv:2508.10889
- Journal Information:
- Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 1 Vol. 10; ISSN 2475-9953
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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