Model for 1/f Flux noise in SQUIDs and Qubits

Area of Science:

• Solid State Physics
• Quantum Computing Materials

Background:

• Superconducting devices are susceptible to 1/f flux noise, hindering their performance.
• The precise microscopic origin of this noise remains a significant challenge in the field.

Purpose of the Study:

• To propose and validate a physical model for 1/f flux noise in superconducting devices.
• To elucidate the role of electron magnetic moments in defect states as the source of this noise.

Main Methods:

• Developed a theoretical model for 1/f flux noise based on electron spin dynamics in defect states.
• Simulated noise generation from randomly oriented defects with a specific density (5x10^17 m^-2).

Main Results:

• The model explains 1/f flux noise as arising from electron magnetic moments trapped in defect states with a broad distribution of escape times.
• Simulations demonstrated that the model yields noise magnitudes consistent with experimental observations.
• Identified Kramers-degenerate ground states and negligible low-temperature transition rates as key factors in locking magnetic moment orientation.

Conclusions:

• The proposed model provides a robust explanation for 1/f flux noise in superconducting devices.
• Electron magnetic moments within defect states are confirmed as a primary source of this ubiquitous noise phenomenon.
• The findings offer a pathway for mitigating noise and improving the coherence of superconducting quantum technologies.