In situ Al2O3 passivation of epitaxial tantalum and aluminum films enables long-term stability in superconducting microwave resonators

• URL: http://arxiv.org/abs/2508.01232v1
• Date: Sat, 02 Aug 2025 07:05:32 GMT
• Title: In situ Al2O3 passivation of epitaxial tantalum and aluminum films enables long-term stability in superconducting microwave resonators
• Authors: Yi-Ting Cheng, Hsien-Wen Wan, Wei-Jie Yan, Lawrence Boyu Young, Yen-Hsun Glen Lin, Kuan-Hui Lai, Wan-Sin Chen, Chao-Kai Cheng, Ko-Hsuan Mandy Chen, Tun-Wen Pi, Yen-Hsiang Lin, Jueinai Kwo, Minghwei Hong,
• Abstract summary: Long-term stability of superconducting microwave resonators is essential for scalable quantum technologies.<n>Here, we demonstrate exceptional stability in microstrip resonators fabricated from epitaxial tantalum and aluminum films, protected by in situ deposited Al2O3 under ultra-high vacuum.
• Score: 1.0154859445071098
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Long-term stability of superconducting microwave resonators is essential for scalable quantum technologies; however, surface and interface degradation continue to limit device stability. Here, we demonstrate exceptional stability in microstrip resonators fabricated from epitaxial tantalum and aluminum films, protected by in situ deposited Al2O3 under ultra-high vacuum. These resonators initially exhibit internal quality factors (Qi) exceeding one million and maintain high performance with minimal degradation after up to fourteen months of air exposure. In contrast, devices relying on native surface oxides show substantial declines in Qi over time, indicating increased microwave losses. X-ray photoelectron spectroscopy reveals that the in situ Al2O3 effectively suppresses interfacial oxidation and preserves the chemical integrity of the underlying superconducting films, whereas native oxides permit progressive oxidation, leading to device degradation. These findings establish a robust, scalable passivation strategy that addresses a longstanding materials challenge in the development of superconducting quantum circuits.

Related papers

• High temporal stability of niobium superconducting resonators by surface passivation with organophosphonate self-assembled monolayers [1.7591465402018172]
  We report the growth of alkyl-phosphonate self-assembled monolayers (SAMs) on Nb thin films following oxide removal.<n>Un-passivated resonators exhibited an 80% increase in loss at single-photon power levels, whereas SAM-passivated resonators maintained excellent temporal stability.
  arXiv  Detail & Related papers  (2025-08-21T20:50:29Z)
• Crystallinity in Niobium oxides: A pathway to mitigate Two-Level System Defects in Niobium 3D Resonator for quantum applications [0.0]
  Two-level-system (TLS) defects are a major source of decoherence in superconducting quantum circuits. We demonstrate the reduction of two-level system losses in three-dimensional superconducting radio frequency (SRF) niobium resonators by a 10-hour high vacuum heat treatment at 650degC.
  arXiv  Detail & Related papers  (2024-10-09T12:02:32Z)
• Site-Controlled Purcell-Induced Bright Single Photon Emitters in Hexagonal Boron Nitride [62.170141783047974]
  Single photon emitters hosted in hexagonal boron nitride (hBN) are essential building blocks for quantum photonic technologies that operate at room temperature. We experimentally demonstrate large-area arrays of plasmonic nanoresonators for Purcell-induced site-controlled SPEs. Our results offer arrays of bright, heterogeneously integrated quantum light sources, paving the way for robust and scalable quantum information systems.
  arXiv  Detail & Related papers  (2024-05-03T23:02:30Z)
• Characterization of process-related interfacial dielectric loss in aluminum-on-silicon by resonator microwave measurements, materials analysis, and imaging [0.0]
  We investigate the influence of the fabrication process on dielectric loss in aluminum-on-silicon superconducting coplanar waveguide resonators. These devices are essential components in superconducting quantum processors. We identify the relative importance of reducing loss at the substrate-metal and the substrate-air interfaces.
  arXiv  Detail & Related papers  (2024-03-01T18:16:28Z)
• Reducing two-level system dissipations in 3D superconducting Niobium resonators by atomic layer deposition and high temperature heat treatment [4.520721347047517]
  We demonstrate the reduction of two-level system losses in three-dimensional superconducting radio frequency (SRF) niobium resonators by atomic layer deposition (ALD) of a 10 nm aluminum oxide Al2O3 thin films. We witness a dissolution of niobium native oxides and the modification of the Al2O3-Nb interface.
  arXiv  Detail & Related papers  (2024-02-06T16:40:52Z)
• Hydrogen crystals reduce dissipation in superconducting resonators [0.0]
  Internal quality factors of superconducting resonators made of granular aluminum can be improved by coating them with micrometric films of para-hydrogen molecular crystals. We attribute the average measured dissipation to absorption of stray terahertz radiation at the crystal-resonator interface. The hydrogen crystal does not introduce additional losses, which is promising for embedding impurities to couple to superconducting thin-film devices in hybrid quantum architectures.
  arXiv  Detail & Related papers  (2023-06-07T02:37:19Z)
• Van der Waals Materials for Applications in Nanophotonics [49.66467977110429]
  We present an emerging class of layered van der Waals (vdW) crystals as a viable nanophotonics platform. We extract the dielectric response of 11 mechanically exfoliated thin-film (20-200 nm) van der Waals crystals, revealing high refractive indices up to n = 5. We fabricate nanoantennas on SiO$$ and gold utilizing the compatibility of vdW thin films with a variety of substrates.
  arXiv  Detail & Related papers  (2022-08-12T12:57:14Z)
• High-efficiency microwave-optical quantum transduction based on a cavity electro-optic superconducting system with long coherence time [52.77024349608834]
  Frequency conversion between microwave and optical photons is a key enabling technology to create links between superconducting quantum processors. We propose a microwave-optical platform based on long-coherence-time superconducting radio-frequency (SRF) cavities. We show that the fidelity of heralded entanglement generation between two remote quantum systems is enhanced by the low microwave losses.
  arXiv  Detail & Related papers  (2022-06-30T17:57:37Z)
• Ternary Metal Oxide Substrates for Superconducting Circuits [65.60958948226929]
  Substrate material imperfections and surface losses are one of the major factors limiting superconducting quantum circuitry from reaching the scale and complexity required to build a practicable quantum computer. Here, we examine two ternary metal oxide materials, spinel (MgAl2O4) and lanthanum aluminate (LaAlO3), with a focus on surface and interface characterization and preparation.
  arXiv  Detail & Related papers  (2022-01-17T06:10:15Z)
• Oxygen Vacancies in Niobium Pentoxide as a Source of Two-Level System Losses in Superconducting Niobium [41.94295877935867]
  oxygen vacancies in the niobium pentoxide drive two-level system (TLS) losses. We identify a major source of quantum decoherence in three-dimensional superconducting radio-frequency (SRF) resonators and two-dimensional transmon qubits composed of oxidized niobium.
  arXiv  Detail & Related papers  (2021-08-30T16:24:07Z)
• Room temperature single-photon emitters in silicon nitride [97.75917079876487]
  We report on the first-time observation of room-temperature single-photon emitters in silicon nitride (SiN) films grown on silicon dioxide substrates. As SiN has recently emerged as one of the most promising materials for integrated quantum photonics, the proposed platform is suitable for scalable fabrication of quantum on-chip devices.
  arXiv  Detail & Related papers  (2021-04-16T14:20:11Z)
• Investigation of microwave loss induced by oxide regrowth in high-Q Nb resonators [0.0]
  We study niobium resonators after removing the native oxides with a hydrofluoric acid etch. We find that losses in quantum devices are reduced by an order of magnitude, with internal Q-factors reaching up to 7 $cdot$ 10$6$ in the single photon regime. Our findings are of particular interest for devices spanning from superconducting qubits, quantum-limited amplifiers, microwave kinetic inductance detectors to single photon detectors.
  arXiv  Detail & Related papers  (2020-12-19T19:14:19Z)
• Nitrogen-vacancy defect emission spectra in the vicinity of an adjustable silver mirror [62.997667081978825]
  Optical emitters of quantum radiation in the solid state are important building blocks for emerging technologies. We experimentally study the emission spectrum of an ensemble of nitrogen-vacancy defects implanted around 8nm below the planar diamond surface.
  arXiv  Detail & Related papers  (2020-03-31T10:43:26Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.