Three-Axis SQUID Magnetometer: Design and Fabrication of a Compact Cryogenic Sensor Assembly

Residual magnetic fields in dilution refrigerators are a source of decoherence and systematic error in quantum systems and fundamental physics experiments. The measurement and characterization of these fields is then a critical step when aiming to minimize any unwanted effects they may contribute. We present the design and fabrication of a compact three-axis Superconducting Quantum Interference Device (SQUID) magnetometer featuring orthogonally-arranged Magnicon M-type sensors within a custom fiberglass housing. 

Three custom non-magnetic PCBs were designed to reduce electromagnetic noise. Each Magnicon SQUID chip was wire-bonded to its PCB to ensure reliable electrical contact without damaging the sensitive superconducting circuits. The housing design was done to provide rigid mechanical support for sensor alignment while minimizing magnetic interference and maintaining appropriate thermal conductivity for 10 mK operation–all within a volume of 2 cm^3. 

This presentation covers the PCB design and wire-bonding process, housing fabrication, and preliminary characterization results. Measurements will be cross-correlated with piezoelectric vibration sensors and a fluxgate magnetometer to quantify sensor performance and distinguish magnetic signals from mechanical vibrations.