Solid-State Microwave Magnetometer with Picotesla-Level Sensitivity

Quantum sensing of low-frequency magnetic fields using nitrogen-vacancy- (N -V) center ensembles has been demonstrated in multiple experiments with sensitivities as low as approximately 1 pT/i/Hz. To date, however, demonstrations of high-frequency magnetometry in the gigahertz regime with N -V dia-mond are orders of magnitude less sensitive, above the nT/i/Hz level. Here, we adapt, for microwave frequencies, techniques that have enabled high-performance low-frequency quantum sensors. Using a custom-grown N-V-enriched diamond combined with a noise-cancellation scheme designed for high -frequency sensing, we demonstrate a Rabi-sequence-based magnetometer able to detect microwave fields near 2.87 GHz with a record sensitivity of 3.4 pT/i/Hz. We demonstrate both amplitude and phase sens-ing and project tunability over a 300-MHz frequency range. This result increases the viability of N -V ensembles to serve as microwave circuitry imagers and near-field probes of antennas.

Automated summary

This study demonstrates a high-performance magnetometer that can detect microwave fields near 2.87 GHz with a sensitivity of 3.4 pT/i/Hz, using techniques adapted from low-frequency quantum sensors. The results increase the potential of N-V ensembles to be used as microwave circuitry imagers and near-field probes of antennas.