QMagPi
Quantum Magnetometer with Proportional-Integral control
What it is
QMagPi — Quantum Magnetometer with Proportional-Integral control — is a compact and portable magnetometer based on an ensemble of nitrogen-vacancy (NV) centres in diamond. It was developed at the PQuest lab in collaboration with WEL.
NV centres in diamond have been explored for a wide range of sensing applications over the last decade because of their unusual quantum properties. The work here is in making that capability small, portable and usable outside a specialised optics bench.
Performance
- Sensitivity~10 nT/√Hz, bandwidth normalised
- Linear dynamic range200 µT, a 20× improvement over the intrinsic range, without losing sensitivity
- Sensor head and electronicsfits in a 10 × 10 × 7 cm box
- Control electronics30 × 25 × 5 cm
The dynamic range comes from closed-loop feedback that locks to the resonance frequency. The published work reports a detailed performance analysis through noise spectra, Allan deviation, and tracking of nanotesla-level magnetic fields in real time.
Shown working
The team demonstrated the magnetometer by tracking, in real time, the movement of a lift car and the opening of its doors — measuring the projection of the magnetic field along one of the NV axes, at ambient temperature and humidity.