Anomalous Frequency Shift in Low-Loss Superconducting Granular Aluminum Resonators

• URL: http://arxiv.org/abs/2608.29282v1
• Date: Sat, 29 Aug 2026 14:06:58 GMT
• Title: Anomalous Frequency Shift in Low-Loss Superconducting Granular Aluminum Resonators
• Abstract summary: Superconducting high-kinetic inductance materials like granular aluminum (grAl) are a versatile part of the circuit quantum electrodynamics (cQED) toolbox.<n>Standard approach pairs electromagnetic simulations of resonator geometry with measured temperature and power dependence of resonance frequency and loss rate.<n>We observe an opposite behavior at the lowest temperatures, contradicting the standard TLS model predictions.
• Score: 0.00897008283486962
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Superconducting high-kinetic inductance materials like granular aluminum (grAl) are a versatile part of the circuit quantum electrodynamics (cQED) toolbox, provided their losses at microwave frequencies are low enough. To further advance the use of grAl in quantum devices, it is indispensable to identify the dominant loss mechanisms. The standard approach pairs electromagnetic simulations of resonator geometry with measured temperature and power dependence of resonance frequency and loss rate. Most materials follow the phenomenological theory of two-level systems (TLSs) at low temperatures, resulting in an initial decrease of the resonance frequency with increasing temperature. In our work, we observe an opposite behavior at the lowest temperatures: The resonance frequency initially increases with both temperature and readout power, contradicting the standard TLS model predictions. We are able to explain a part of the data by an alternative mechanism associated with the effect of superconducting quasiparticles in a granular system with spatially-nonuniform gap. Yet, the observed change in the resonance frequency with temperature is not matched by a proportional change in the loss rate. We also observe anomalous positive frequency responses following high-energy events, characterized by several time scales. While anomalous behavior has been reported previously in grAl, the disagreement with standard models is particularly visible in our devices thanks to their exceptionally low loss rates.

Related papers

• Frequency Fluctuations in Nanomechanical Resonators due to Quantum Defects [0.0]
  Two-level system (TLS) defects govern dissipation at millikelvin temperatures.<n>We observe fast frequency fluctuations of phononic crystal nanomechanical resonators.<n>The frequency noise is well-explained by mechanical coupling to individual far off-resonant TLS, which are either thermally excited or strongly coupled to thermal fluctuators.
  arXiv  Detail & Related papers  (2025-01-14T18:10:29Z)
• Quantum interaction of sub-relativistic aloof electrons with mesoscopic samples [91.3755431537592]
  Relativistic electrons experience very slight wave packet distortion and negligible momentum recoil when interacting with nanometer-sized samples. Modelling fast electrons as classical point-charges provides extremely accurate theoretical predictions of energy-loss spectra.
  arXiv  Detail & Related papers  (2022-11-14T15:22:37Z)
• Thermal self-oscillations in monolayer graphene coupled to a superconducting microwave cavity [58.720142291102135]
  We observe thermal self-oscillations in a monolayer graphene flake coupled to superconducting resonator. The experimental observations fit well with theoretical model based on thermal instability. The modelling of the oscillation sidebands provides a method to evaluate electron phonon coupling in disordered graphene sample at low energies.
  arXiv  Detail & Related papers  (2022-05-27T15:38:41Z)
• Power and temperature dependent model for High Q superconductors [0.0]
  Measuring the internal quality factor of coplanar waveguide superconducting resonators is an established method of determining small losses in superconducting devices.<n> excess non-equilibrium quasiparticles can also limit the quality factor of the planar superconducting resonators used in circuit quantum electrodynamics.<n>Here a two-temperature, power and temperature dependent model is proposed to evaluate resonator losses for isolating TLS and quasiparticle loss simultaneously.
  arXiv  Detail & Related papers  (2022-05-12T18:10:24Z)
• Dynamics of Transmon Ionization [94.70553167084388]
  We numerically explore the dynamics of a driven transmon-resonator system under strong and nearly resonant measurement drives. We find clear signatures of transmon ionization where the qubit escapes out of its cosine potential.
  arXiv  Detail & Related papers  (2022-03-21T18:00:15Z)
• Experimentally revealing anomalously large dipoles in a quantum-circuit dielectric [50.591267188664666]
  Two-level systems (TLSs) intrinsic to glasses induce decoherence in many modern quantum devices. We show the existence of two distinct ensembles of TLSs, interacting weakly and strongly with phonons. Results may shed new light on the low temperature characteristics of amorphous solids.
  arXiv  Detail & Related papers  (2021-10-20T19:42:22Z)
• Anomalous Loss Reduction Below Two-Level System Saturation in Aluminum Superconducting Resonators [0.0]
  capacitively-coupled aluminum half-wavelength coplanar waveguide resonators are investigated. Two-level systems (TLS) become the dominant source of loss in the few-photon and low temperature regime.
  arXiv  Detail & Related papers  (2021-09-24T04:29:21Z)
• Measurement of the Low-temperature Loss Tangent of High-resistivity Silicon with a High Q-factor Superconducting Resonator [58.720142291102135]
  We present the direct loss tangent measurement of a high-resist intrinsicivity (100) silicon wafer in the temperature range from 70 mK to 1 K. The measurement was performed using a technique that takes advantage of a high quality factor superconducting niobium resonator.
  arXiv  Detail & Related papers  (2021-08-19T20:13:07Z)
• Frequency fluctuations of ferromagnetic resonances at milliKelvin temperatures [50.591267188664666]
  Noise is detrimental to device performance, especially for quantum coherent circuits. Recent efforts have demonstrated routes to utilizing magnon systems for quantum technologies, which are based on single magnons to superconducting qubits. Researching the temporal behavior can help to identify the underlying noise sources.
  arXiv  Detail & Related papers  (2021-07-14T08:00:37Z)
• Quantum versus Classical Regime in Circuit Quantum Acoustodynamics [8.00487309438664]
  We experimentally study a circuit quantum acoustodynamics system, which consists of a superconducting artificial atom. We show that the propagation of microwave photons in the microwave transmission line can be controlled by a few phonons in the acoustic wave resonator.
  arXiv  Detail & Related papers  (2020-11-10T12:49:35Z)

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.