# Model for 1/f Flux noise in Superconducting Aluminum Devices: Impact of External Magnetic Fields

## TL;DR

This paper presents a model explaining how external magnetic fields influence 1/f flux noise in aluminum superconducting devices, suggesting a method to reduce noise impact in quantum circuits.

## Contribution

The paper introduces a new model based on impurity spin flips that accounts for the effects of external magnetic fields on flux noise in superconducting aluminum devices.

## Key findings

- External magnetic fields can alter flux noise characteristics.
- The model explains the transition from 1/f noise to Lorentzian peaks.
- Applying magnetic fields can reduce flux noise in qubits.

## Abstract

Superconducting quantum interference devices (SQUIDs) and related circuits made of aluminum are known to display $1/\omega$ flux noise, where $\omega$ is frequency. A recent experiment showed that the application of an external magnetic field in the $10-100$~G range changed the noise to a single Lorentzian peaked at $\omega=0$. Here it is shown that a model based on independent impurity spin flips with coexisting cross and direct mechanisms of spin relaxation may explain these experiments. The model shows that application of an external magnetic field can be used to reduce the impact of flux noise in qubits.