Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE Transactions on Applied Superconductivity

Embedding NbN Nanowires Into Quantum Circuits With a Neon Focused Ion Beam

Jonathan Burnett, James T. Sagar, Paul A. Warburton, J. C. Fenton

Published Feb 4, 2016• 6 citations
Publisher

Abstract

Parasitic two-level systems are generally present in superconducting circuits as a result of conventional fabrication and processing, and these lead to noise and loss of coherence in quantum systems. We examine the use of a Ne focused ion beam for producing nanowires integrated into superconducting circuits with a minimized density of parasitic two-level systems. We report measurements of nanowires produced by Ne focused-ion-beam milling in NbN resonators. The resonator losses increase after the nanowire is fabricated, with the Q factor decreasing by ~30% to ~105, which is a factor 10-100 higher than in the most closely comparable circuits previously measured. This indicates that the Ne focused ion beam is a promising route for creating superconducting-nanowire-based devices with low levels of decoherence.

DOI
10.1109/tasc.2016.2525988

Related papers

Low-Loss Superconducting Nanowire Circuits Using a Neon Focused Ion Beam

Jonathan Burnett, James T. Sagar, Oscar W. Kennedy +2 more

Quantum circuits based on superconducting nanowires have recently made an impact in the development of devices harnessing phase slip, superinductance, and Josephson effects. Exploiting this rich physics is difficult, though, due to fabrication-induced, parasitic two-level systems, which cause high levels of loss and decoherence. Using a focused beam of neon ions, the authors embed superconducting nanowires into coplanar waveguide resonators and realize much lower losses than in previous devices. This achievement suggests excellent prospects for this class of circuitry.

arXiv:1708.02502•Physical Review Applied•Jul 31, 2017•34 citations

Nonlinear Quantum Processes in Superconducting Resonators Terminated by Neon-Focused-Ion-Beam-Fabricated Superconducting Nanowires

Jamie Potter, Oscar W. Kennedy, J. C. Fenton +1 more

We have used a neon focused-ion-beam to fabricate both nanoscale Nb Dayem bridges and NbN phase-slip nanowires located at the short-circuited end of quarter-wavelength coplanar waveguide resonators. The Dayem bridge devices show flux-tunability and intrinsic quality factor exceeding 10 000 at 300 mK up to local fields of at least 60 mT. The NbN nanowires show signatures of incoherent quantum tunneling of flux at 300 mK.

arXiv:2011.02437•IEEE Transactions on Applied Superconductivity•Aug 21, 2020•4 citations

Controllable Tunneling of Single Flux Quanta Mediated by Quantum Phase Slip in Disordered Superconducting Loops

Jamie Potter, J. C. Fenton, Paul A. Warburton

Quantum phase slip (QPS) is the exact dual to the well-known Josephson effect. Although there are numerous proposals for applications of QPS devices, experimental work to develop these remains in the relatively early stages. Significant barriers to exploiting QPS nanowires for useful technologies still exist, such as establishing robust nanowire-fabrication methods that allow coupling to low-loss circuits, and demonstrating control over the QPS process with an experimenter-controlled external bias. Here we report experiments that show that both of these barriers have been overcome. We present measurements at 300 mK of $\mathrm{Nb}\mathrm{N}$ coplanar-waveguide (CPW) resonators embedded with nanowires fabricated using a neon focused ion beam. The internal quality factor exceeds $2\ifmmode\times\else\texttimes\fi{}{10}^{4}$---significantly higher than previously reported in comparable experiments. The resonator frequency tunes periodically with an applied magnetic field, revealing tunneling of the order parameter that always occurs at half-integer values of the applied flux. In contrast to previous studies of single QPS, the order-parameter tunneling is shown to be adiabatic, demonstrating improved control over energy dissipation in nanowire QPS circuits. Our results highlight a promising pathway towards realizing low-loss nanowire-based QPS devices.

arXiv:2301.04411•Physical Review Applied•Feb 1, 2023•5 citations

Millikelvin Nb nanoSQUID-embedded tunable resonator fabricated with a neon focused-ion-beam

Jamie Potter, Laith Meti, Gemma Chapman +3 more

SQUID-embedded superconducting resonators are of great interest due to their potential for coupling highly scalable superconducting circuits with quantum memories based on solid-state spin ensembles. Such an application requires a high-Q, frequency-tunable resonator that is both resilient to magnetic field and able to operate at millikelvin temperatures. These requirements motivate the use of a higher Hc metal such as niobium; however, the challenge then becomes to sufficiently reduce the operating temperature. We address this by presenting a monolithic Nb nanoSQUID-embedded resonator, where neon focused-ion-beam fabrication of the nanoSQUID results in a device displaying frequency tunability at T=16 mK. In order to assess the applicability of the device for coupling to small spin clusters, we characterize the flux sensitivity as a function of microwave drive power and externally applied magnetic field and find that the noise is dominated by dielectric noise in the resonator. Finally, we discuss improvements to the device design that can dramatically improve the flux sensitivity, which highlights the promise of Nb SQUID-embedded resonators for hybrid superconductor-spin applications.

arXiv:2412.16045•Applied Physics Letters•Jan 3, 2025•5 citations

Superconducting Nanowire Fabrication on Niobium Nitride using Helium Ion Irradiation

Glenn D. Martinez, Drew Buckley, Ilya Charaev +3 more

Superconducting devices are prone to reduced performance caused by impurities and defects along the edges of their wires, which can lead to local current crowding. In this study, we explored the use of helium ion irradiation to modify the lattice structure of the superconducting material to change its intrinsic properties. The process will allow us to directly pattern devices and potentially improve the quality of the nanowires. To achieve this, we used the ion beam from a scanning helium ion microscope (HIM) to localize damage on a superconducting material to create a nanowire. Two experiments were performed in this study. First, a range of helium ion doses was exposed on a niobium nitride (NbN) microwire to determine the estimated dose density to suppress superconductivity. Using the results of this first experiment, nanowires were patterned onto a microwire, and the current-voltage characteristics were measured for each sample. Our results showed that helium ion irradiation is an effective resistless fabrication method for superconducting nanowires.

arXiv:2003.02898•Mar 5, 2020•4 citations

Niobium quantum interference microwave circuits with monolithic three-dimensional nanobridge junctions

Kevin Uhl, Daniel Hackenbeck, Janis Peter +3 more

Nonlinear microwave circuits are key elements for many groundbreaking research directions and technologies, such as quantum computation and quantum sensing. The majority of microwave circuits with Josephson nonlinearities to date are based on aluminum thin films; therefore, they are severely restricted in their operation range regarding temperatures and external magnetic fields. Here, we present the realization of superconducting niobium microwave resonators with integrated, three-dimensional (3D) nanobridge-based superconducting quantum interference devices. The 3D nanobridges (constriction weak links) are monolithically patterned into prefabricated microwave $LC$ circuits using neon focused-ion-beam milling, and the resulting quantum interference circuits show frequency tunabilities, flux responsivities, and Kerr nonlinearities on par with comparable aluminum nanobridge devices, but with the perspective of a much larger operation parameter regime. Our results demonstrate that neon focused-ion-beam milling is a promising method for fabricating 3D constriction junctions with flexible parameters and reveal great potential for application of the resulting microwave circuits in hybrid systems with, e.g., magnons and spin ensembles or in flux-mediated optomechanics.

Physical Review Applied•Feb 27, 2024•7 citations
Parasitic two-level systems are generally present in superconducting circuits as a result of conventional fabrication and processing, and these lead to noise and loss of coherence in quantum systems. We examine the use of a Ne focused ion beam for producing nanowires integrated into superconducting circuits with a minimized density of parasitic two-level systems. We report measurements of nanowires produced by Ne focused-ion-beam milling in NbN resonators. The resonator losses increase after the nanowire is fabricated, with the Q factor decreasing by ~30% to ~105, which is a factor 10-100 higher than in the most closely comparable circuits previously measured. This indicates that the Ne focused ion beam is a promising route for creating superconducting-nanowire-based devices with low levels of decoherence.
Quantum circuits based on superconducting nanowires have recently made an impact in the development of devices harnessing phase slip, superinductance, and Josephson effects. Exploiting this rich physics is difficult, though, due to fabrication-induced, parasitic two-level systems, which cause high levels of loss and decoherence. Using a focused beam of neon ions, the authors embed superconducting nanowires into coplanar waveguide resonators and realize much lower losses than in previous devices. This achievement suggests excellent prospects for this class of circuitry.
Quantum phase slip (QPS) is the exact dual to the well-known Josephson effect. Although there are numerous proposals for applications of QPS devices, experimental work to develop these remains in the relatively early stages. Significant barriers to exploiting QPS nanowires for useful technologies still exist, such as establishing robust nanowire-fabrication methods that allow coupling to low-loss circuits, and demonstrating control over the QPS process with an experimenter-controlled external bias. Here we report experiments that show that both of these barriers have been overcome. We present measurements at 300 mK of NbN\mathrm{Nb}\mathrm{N}NbN coplanar-waveguide (CPW) resonators embedded with nanowires fabricated using a neon focused ion beam. The internal quality factor exceeds $2\ifmmode\times\else\texttimes\fi{}{10}^{4}$---significantly higher than previously reported in comparable experiments. The resonator frequency tunes periodically with an applied magnetic field, revealing tunneling of the order parameter that always occurs at half-integer values of the applied flux. In contrast to previous studies of single QPS, the order-parameter tunneling is shown to be adiabatic, demonstrating improved control over energy dissipation in nanowire QPS circuits. Our results highlight a promising pathway towards realizing low-loss nanowire-based QPS devices.
SQUID-embedded superconducting resonators are of great interest due to their potential for coupling highly scalable superconducting circuits with quantum memories based on solid-state spin ensembles. Such an application requires a high-Q, frequency-tunable resonator that is both resilient to magnetic field and able to operate at millikelvin temperatures. These requirements motivate the use of a higher Hc metal such as niobium; however, the challenge then becomes to sufficiently reduce the operating temperature. We address this by presenting a monolithic Nb nanoSQUID-embedded resonator, where neon focused-ion-beam fabrication of the nanoSQUID results in a device displaying frequency tunability at T=16 mK. In order to assess the applicability of the device for coupling to small spin clusters, we characterize the flux sensitivity as a function of microwave drive power and externally applied magnetic field and find that the noise is dominated by dielectric noise in the resonator. Finally, we discuss improvements to the device design that can dramatically improve the flux sensitivity, which highlights the promise of Nb SQUID-embedded resonators for hybrid superconductor-spin applications.
Superconducting devices are prone to reduced performance caused by impurities and defects along the edges of their wires, which can lead to local current crowding. In this study, we explored the use of helium ion irradiation to modify the lattice structure of the superconducting material to change its intrinsic properties. The process will allow us to directly pattern devices and potentially improve the quality of the nanowires. To achieve this, we used the ion beam from a scanning helium ion microscope (HIM) to localize damage on a superconducting material to create a nanowire. Two experiments were performed in this study. First, a range of helium ion doses was exposed on a niobium nitride (NbN) microwire to determine the estimated dose density to suppress superconductivity. Using the results of this first experiment, nanowires were patterned onto a microwire, and the current-voltage characteristics were measured for each sample. Our results showed that helium ion irradiation is an effective resistless fabrication method for superconducting nanowires.
Nonlinear microwave circuits are key elements for many groundbreaking research directions and technologies, such as quantum computation and quantum sensing. The majority of microwave circuits with Josephson nonlinearities to date are based on aluminum thin films; therefore, they are severely restricted in their operation range regarding temperatures and external magnetic fields. Here, we present the realization of superconducting niobium microwave resonators with integrated, three-dimensional (3D) nanobridge-based superconducting quantum interference devices. The 3D nanobridges (constriction weak links) are monolithically patterned into prefabricated microwave LCLCLC circuits using neon focused-ion-beam milling, and the resulting quantum interference circuits show frequency tunabilities, flux responsivities, and Kerr nonlinearities on par with comparable aluminum nanobridge devices, but with the perspective of a much larger operation parameter regime. Our results demonstrate that neon focused-ion-beam milling is a promising method for fabricating 3D constriction junctions with flexible parameters and reveal great potential for application of the resulting microwave circuits in hybrid systems with, e.g., magnons and spin ensembles or in flux-mediated optomechanics.