Superconducting Quantum Magnetometer Based on Flux Focusing Effect for High-Sensitivity Applications

Area of Science:

• Quantum sensing
• Superconducting devices

Background:

• Conventional DC SQUID magnetometers often require complex flux transformers or multi-loop designs.
• Achieving high magnetic field sensitivity in compact devices presents engineering challenges.

Purpose of the Study:

• To develop a simple, high-sensitivity superconducting quantum magnetometer.
• To overcome performance degradation associated with high inductance parameters in DC SQUIDs.

Main Methods:

• Exploited flux focusing within a superconducting loop.
• Employed a bare DC SQUID with a large washer-shaped superconducting ring.
• Damped the inductance of the DC SQUID to compensate for high inductance parameter (βL).

Main Results:

• Achieved a magnetic field sensitivity (BΦ) below 1 nT/√Φ0.
• Developed a compact magnetometer with dimensions of 5 × 5 mm².
• Demonstrated a magnetic field noise spectral density of 8 fT/√Hz with a low-frequency noise knee at 2 Hz.

Conclusions:

• The simple design and effective inductance damping enable high performance.
• This magnetometer is suitable for various high-sensitivity applications, including magnetoencephalography.
• The device offers a promising alternative for sensitive magnetic field measurements.