Imaging of microwave magnetic field orientation using continuous-wave experiments on nitrogen-vacancy centers in diamond

TL;DR

This paper introduces a simplified continuous-wave method for imaging the orientation of microwave magnetic fields at the nanoscale using nitrogen-vacancy centers in diamond, eliminating the need for pulsed measurements.

Contribution

The authors demonstrate a continuous-wave technique for imaging microwave magnetic field orientation with NV centers, simplifying previous pulsed methods and enabling easier practical applications.

Findings

Successfully imaged microwave field orientation using continuous-wave experiments.

Able to determine the direction of arbitrary microwave fields with NV centers of two orientations.

Projected microwave fields onto a plane can be imaged with a single NV center.

Abstract

Imaging of microwave magnetic fields with nano-scale resolution has interesting applications. Specifically, detecting the orientation of the microwave fields is useful in condensed matter physics and quantum control. However, most of the existing methods for microwave field imaging are limited to detecting the magnitude of the fields. Due to their small sensor size and favorable optical and spin properties, nitrogen-vacancy (NV) centers in diamond are highly suitable for imaging dc and ac magnetic fields. The reported methods for detecting the orientation of microwave magnetic fields use pulsed Rabi frequency measurements. Here, we demonstrate imaging of the orientation of microwave magnetic fields by only using continuous-wave experiments on NV centers. This simplifies the sensor apparatus and is particularly advantageous in applications where pulsing of the target microwave field is not possible. The method requires static bias magnetic field oriented perpendicular to the quantization axis of NV centers. We detect the direction of an arbitrary microwave magnetic field using NV centers of two different orientations. Moreover, we demonstrate that the projection of the microwave fields onto a plane can be imaged using NV centers of single orientation. It can be straightforwardly implemented using a single NV center.