High temporal stability of niobium superconducting resonators by surface passivation with organophosphonate self-assembled monolayers
arXiv:2508.15957 · doi:10.1038/s43246-025-01068-8
Abstract
One main limiting factor towards achieving high coherence times in superconducting circuits is two level system (TLS) losses. Mitigating such losses requires controlling the formation of native oxides at the metal-air interface. Here, we report the growth of alkyl-phosphonate self-assembled monolayers (SAMs) on Nb thin films following oxide removal. The impact of passivation was evaluated via the performance of coplanar waveguide resonators at 10mK, in terms of quality factor and resonant frequency, over six days of air exposure. Un-passivated resonators exhibited an ~80% increase in loss at single-photon power levels, whereas SAM-passivated resonators maintained excellent temporal stability, attributed to suppressed oxide regrowth. By employing a two-component TLS model, we discern distinct prominent loss channels for each resonator type and quantified the characteristic TLS loss of the SAMs to be ~5x10^-7. We anticipate our passivation methodology to offer a promising route toward industrial-scale qubit fabrication, particularly where long-term device stability is critical.
arXiv comment35 pages, 21 figures, Harsh Gupta and Marc Tornow are the corresponding authors
References in corpus (23)
- Superconducting Qubits: Current State of Play
- Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
- Large-area, ensemble molecular electronics: Motivation and challenges
- Reducing intrinsic loss in superconducting resonators by surface treatment and deep etching of silicon substrates
- Surface loss simulations of superconducting coplanar waveguide resonators
- Improving the Coherence Time of Superconducting Coplanar Resonators
- Interacting two-level defects as sources of fluctuating high-frequency noise in superconducting circuits
- Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation
- Understanding Quality Factor Degradation in Superconducting Niobium Cavities at Low Microwave Field Amplitudes
- Identifying optimal cycles in quantum thermal machines with reinforcement-learning
- Investigation of microwave loss induced by oxide regrowth in high-Q Nb resonators
- Suppression of 1/f noise in solid state quantum devices by surface spin desorption
- Losses in coplanar waveguide resonators at millikelvin temperatures
- Temperature Dependence of the Frequency and Noise of Superconducting Coplanar Waveguide Resonators
- Internal loss of superconducting resonators induced by interacting two level systems
- Loss mechanisms in superconducting thin film microwave resonators
- Noise and loss of superconducting aluminium resonators at single photon energies
- Revealing the nonlinear response of a tunneling two-level system ensemble using coupled modes
- Low loss hybrid Nb/Au superconducting resonators for quantum circuit applications
- Modelling dielectric loss in superconducting resonators: Evidence for interacting atomic two-level systems at the Nb/oxide interface
- Annealing reduces SiN microwave-frequency dielectric loss in superconducting resonators
- Anomalous Loss Reduction Below Two-Level System Saturation in Aluminum Superconducting Resonators
- Low microwave loss in deposited Si and Ge thin-film dielectrics at single-photon power and low temperatures