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Microscopic model of critical current noise in Josephson junctions
Magdalena Constantin1, Clare C Yu
1Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA.
Physical Review Letters
|February 1, 2008
Summary
Fluctuating two-level systems in Josephson junctions create 1/f noise, dependent on barrier thickness. This model aligns with experimental critical current noise measurements in aluminum-based junctions.
Area of Science:
- Condensed Matter Physics
- Quantum Electronics
Background:
- Josephson junctions are crucial superconducting devices.
- Understanding noise in these junctions is vital for quantum technologies.
Purpose of the Study:
- To develop a microscopic model for critical current noise in Josephson junctions.
- To investigate the influence of fluctuating two-level systems on noise spectra.
- To analyze the impact of tunnel barrier properties on noise.
Main Methods:
- A simple microscopic model was developed.
- The model analyzes fluctuating two-level systems within the tunnel barrier.
- The dependence of noise on barrier thickness (L) was calculated.
Main Results:
- The model predicts low-frequency 1/f noise.
- Noise intensity scales with barrier thickness as L^5.
- Results show good agreement with experimental data for Al/AlOx/Al junctions.
- Noise sensitivity to tunnel barrier nonuniformity was explored.
Conclusions:
- Fluctuating two-level systems are a source of 1/f noise in Josephson junctions.
- The L^5 dependence provides a testable prediction for future experiments.
- The model offers insights into noise mechanisms relevant for superconducting device performance.
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