Towards Geometric Phase Magnetometry in Nitrogen-Vacancy Center Ensembles

Nitrogen vacancy (NV) centers in diamonds have emerged as compelling quantum sensors, par-

ticularly as sensitive magnetometers at ambient conditions providing sub-micrometer resolution.

Conventionally, interferometry-based protocols (e.g., Ramsey) for broadband magnetometry encode

magnetic field information into the dynamic phase accumulated by the NV spin state. However, for

the detection of large magnetic fields, the sensor’s dynamic range and sensitivity are constrained by

phase ambiguities upon accumulating phase ≥ 2π. To circumvent these limitations, Arai et al. (2018)

introduced the use of geometric phases for magnetometry with a single NV center. Extending these

methods to an ensemble of NV centers, we examine the impact of magnetic disorder and control

field inhomogeneities through numerical simulations. Furthermore, we present preliminary exper-

imental results including polarization of the NV nitrogen nuclear spin and the implementation of

fabricated transmission lines for homogeneous delivery of microwave control fields. These findings

offer promising insights into enhancing the capabilities of NV based magnetometers.