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All-nitride superconducting qubits based on atomic layer deposition

Nature Materials (2026)Cite this article

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Abstract

The development of large-scale quantum processors benefits from superconducting qubits that can operate at elevated temperatures and be fabricated with scalable, foundry-compatible processes. Atomic layer deposition (ALD) is increasingly being adopted as an industrial standard for thin-film growth, particularly in applications requiring precise control over layer thickness and composition. Here we report superconducting qubits based on NbN/AlN/NbN trilayers deposited entirely by ALD. By varying the number of ALD cycles used to form the AlN barrier, we achieve Josephson tunnelling through barriers of different thicknesses, with critical current density spanning seven orders of magnitude, demonstrating the uniformity and versatility of the process. Owing to the high critical temperature of NbN, transmon qubits based on these all-nitride trilayers exhibit microsecond-scale relaxation times, even at temperatures above 300 mK. These results establish ALD as a viable low-temperature deposition technique for superconducting quantum circuits and position all-nitride ALD qubits as a promising platform for operation at elevated temperatures.

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Fig. 1: ALD growth sequence and atomic-scale characterization of NbN/AlN/NbN trilayer.
Fig. 2: Device schematics and I–V characterization at 4 K.
Fig. 3: Qubit performance at the base temperature.
Fig. 4: Qubit performance at elevated temperatures.

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The data supporting this study are included in the Article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

We thank D. Jena, H. G. Xing, V. Fatemi, F. Rana, C. E. Dreyer, P. L. McMahon, A. Ithepalli and M. Verma for helpful and inspirational discussions. We also thank Y. Sun, M. Rooks, L. McCabe, Y. Shin, K. Woods and S. Sohn for their assistance and guidance in device fabrications. This work was supported by the Air Force Office of Sponsored Research under grant number FA9550-23-1-0688 and by the Army Research Office under grant number W911NF-24-2-0240. H.X.T. acknowledges support from the Office of Naval Research under grant number N00014-23-1-2021. The use of the fabrication facilities was supported by the Yale Institute for Nanoscience and Quantum Engineering (YINQE) and the Yale SEAS Cleanroom. The TWPA used in this experiment was provided by IARPA and MIT Lincoln Laboratory. The work on STEM made use of the electron microscopy facility of the Cornell Center for Materials Research (CCMR) with support from the National Science Foundation Materials Research Science and Engineering Centers (MRSEC) program (DMR1719875). The Thermo Fisher Spectra 300 X-CFEG device was acquired with support from PARADIM, an NSF MIP (DMR-2039380) and Cornell University. N.P. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant number DGE2139899. P.G. and B.M. acknowledge support from the Air Force Office of Sponsored Research under grant number 162023-22608.

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Authors and Affiliations

  1. Department of Electrical and Computer Engineering, Yale University, New Haven, CT, USA

    Danqing Wang, Yufeng Wu, Manuel C. C. Pace & Hong X. Tang

  2. Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA

    Naomi Pieczulewski

  3. Department of Materials Design and Innovation, University at Buffalo—SUNY, Buffalo, NY, USA

    Prachi Garg & Baishakhi Mazumder

  4. Department of Applied Physics, Yale University, New Haven, CT, USA

    Charlotte G. L. Bøttcher

  5. School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA

    David A. Muller

  6. Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY, USA

    David A. Muller

Authors
  1. Danqing Wang
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Contributions

H.X.T. and D.W. conceived the research and designed the experiments. D.W. deposited the ALD films and fabricated the devices with contributions from M.C.C.P. D.W. performed the d.c. measurement with contributions from C.G.L.B. Y.W. constructed the RF measurement setup and Y.W. and D.W. performed the RF measurement. D.W., C.G.L.B. and M.C.C.P. provided the theoretical analysis. N.P. performed the STEM characterization. P.G. conducted the APT characterization. H.X.T., D.A.M. and B.M. supervised the project. D.W., N.P., P.G. and H.X.T. wrote the manuscript with input from all authors.

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Correspondence to Hong X. Tang.

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Nature Materials thanks Cameron Kopas and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

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Supplementary Figs. S1–S4, Sections I–VI and Tables S1 and S2.

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Statistical source data for Fig. 1b.

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Statistical source data for Fig. 2b.

Source Data Fig. 3

Statistical source data for Fig. 3a–c,e,f.

Source Data Fig. 4

Statistical source data for Fig. 4a,b.

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Wang, D., Wu, Y., Pieczulewski, N. et al. All-nitride superconducting qubits based on atomic layer deposition. Nat. Mater. (2026). https://doi.org/10.1038/s41563-025-02448-8

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