npj Quantum Information (Apr 2024)
Systematic improvements in transmon qubit coherence enabled by niobium surface encapsulation
- Mustafa Bal,
- Akshay A. Murthy,
- Shaojiang Zhu,
- Francesco Crisa,
- Xinyuan You,
- Ziwen Huang,
- Tanay Roy,
- Jaeyel Lee,
- David van Zanten,
- Roman Pilipenko,
- Ivan Nekrashevich,
- Andrei Lunin,
- Daniel Bafia,
- Yulia Krasnikova,
- Cameron J. Kopas,
- Ella O. Lachman,
- Duncan Miller,
- Josh Y. Mutus,
- Matthew J. Reagor,
- Hilal Cansizoglu,
- Jayss Marshall,
- David P. Pappas,
- Kim Vu,
- Kameshwar Yadavalli,
- Jin-Su Oh,
- Lin Zhou,
- Matthew J. Kramer,
- Florent Lecocq,
- Dominic P. Goronzy,
- Carlos G. Torres-Castanedo,
- P. Graham Pritchard,
- Vinayak P. Dravid,
- James M. Rondinelli,
- Michael J. Bedzyk,
- Mark C. Hersam,
- John Zasadzinski,
- Jens Koch,
- James A. Sauls,
- Alexander Romanenko,
- Anna Grassellino
Affiliations
- Mustafa Bal
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Akshay A. Murthy
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Shaojiang Zhu
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Francesco Crisa
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Xinyuan You
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Ziwen Huang
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Tanay Roy
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Jaeyel Lee
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- David van Zanten
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Roman Pilipenko
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Ivan Nekrashevich
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Andrei Lunin
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Daniel Bafia
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Yulia Krasnikova
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Cameron J. Kopas
- Rigetti Computing
- Ella O. Lachman
- Rigetti Computing
- Duncan Miller
- Rigetti Computing
- Josh Y. Mutus
- Rigetti Computing
- Matthew J. Reagor
- Rigetti Computing
- Hilal Cansizoglu
- Rigetti Computing
- Jayss Marshall
- Rigetti Computing
- David P. Pappas
- Rigetti Computing
- Kim Vu
- Rigetti Computing
- Kameshwar Yadavalli
- Rigetti Computing
- Jin-Su Oh
- Ames Laboratory, U.S. Department of Energy
- Lin Zhou
- Ames Laboratory, U.S. Department of Energy
- Matthew J. Kramer
- Ames Laboratory, U.S. Department of Energy
- Florent Lecocq
- National Institute of Standards and Technology
- Dominic P. Goronzy
- Department of Materials Science and Engineering, Northwestern University
- Carlos G. Torres-Castanedo
- Department of Materials Science and Engineering, Northwestern University
- P. Graham Pritchard
- Department of Materials Science and Engineering, Northwestern University
- Vinayak P. Dravid
- Department of Materials Science and Engineering, Northwestern University
- James M. Rondinelli
- Department of Materials Science and Engineering, Northwestern University
- Michael J. Bedzyk
- Department of Materials Science and Engineering, Northwestern University
- Mark C. Hersam
- Department of Materials Science and Engineering, Northwestern University
- John Zasadzinski
- Department of Physics, Illinois Institute of Technology
- Jens Koch
- Department of Physics and Astronomy, Northwestern University
- James A. Sauls
- Hearne Institute of Theoretical Physics, Department of Physics and Astronomy, Louisiana State University
- Alexander Romanenko
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- Anna Grassellino
- Superconducting Quantum Materials and Systems Division, Fermi National Accelerator Laboratory (FNAL)
- DOI
- https://doi.org/10.1038/s41534-024-00840-x
- Journal volume & issue
-
Vol. 10,
no. 1
pp. 1 – 8
Abstract
Abstract We present a transmon qubit fabrication technique that yields systematic improvements in T 1 relaxation times. We encapsulate the surface of niobium and prevent the formation of its lossy surface oxide. By maintaining the same superconducting metal and only varying the surface, this comparative investigation examining different capping materials, such as tantalum, aluminum, titanium nitride, and gold, as well as substrates across different qubit foundries demonstrates the detrimental impact that niobium oxides have on coherence times of superconducting qubits, compared to native oxides of tantalum, aluminum or titanium nitride. Our surface-encapsulated niobium qubit devices exhibit T 1 relaxation times 2–5 times longer than baseline qubit devices with native niobium oxides. When capping niobium with tantalum, we obtain median qubit lifetimes above 300 μs, with maximum values up to 600 μs. Our comparative structural and chemical analysis provides insight into why amorphous niobium oxides may induce higher losses compared to other amorphous oxides.
