Oxide-nitride heteroepitaxy for low-loss dielectrics in superconducting quantum circuits

Quantum Physics [Submitted on 30 Mar 2026] Oxide-nitride heteroepitaxy for low-loss dielectrics in superconducting quantum circuits David A. Garcia-Wetten, Mitchell J. Walker, Peter G. Lim, André Vallières, Maria G. Jimenez-Guillermo, Miguel A. Alvarado, Dominic P. Goronzy, Anna Grassellino, Jens Koch, Vinayak P. Dravid, Mark C. Hersam, Michael J. Bedzyk Superconducting qubits show great promise for the realization of fault-tolerant quantum computing, but lossy, amorphous dielectrics limit current technology. Identifying highly crystalline and stoichiometric dielectrics with intrinsically low microwave loss is therefore a central materials challenge, yet experimentally validated platforms remain scarce. In this work, we integrate a crystalline dielectric into a heteroepitaxial TiN/\gamma-Al_2O_3/TiN trilayer grown via pulsed laser deposition. Correlative high-resolution imaging, diffraction, and spectroscopy measurements confirm the single-crystal quality and chemical integrity of all layers, with minimal defects and limited anion interdiffusion across the oxide-nitride interfaces. Using microwave lumped-element resonators with parallel-plate capacitors, we report the first direct measurement of the dielectric loss of epitaxial \gamma-Al_2O_3, for which we find a low intrinsic two-level system loss, \delta_{\text{TLS}}^0 = (2.8 \pm 0.1) \times 10^{-5}. These results establish heteroepitaxial oxides on transition metal nitrides as an attractive materials platform for superconducting quantum circuits, particularly for integration into compact device architectures such as merged-element transmons and microwave kinetic inductance detectors. Comments: 38 pages, 10 figures Subjects: Quantum Physics (quant-ph); Materials Science (cond-mat.mtrl-sci); Superconductivity (cond-mat.supr-con) Report number: FERMILAB-PUB-26-0206-SQMS Cite as: arXiv:2603.29065 [quant-ph]   (or arXiv:2603.29065v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2603.29065 Focus to learn more Submission history From: Peter Gilhwan Lim [view email] [v1] Mon, 30 Mar 2026 23:05:18 UTC (6,534 KB) Access Paper: view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-03 Change to browse by: cond-mat cond-mat.mtrl-sci cond-mat.supr-con References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)