Efficient, uniform, and large area microwave magnetic coupling to NV centers in diamond using double split-ring resonators.

We report on the development and utilization of a double split-ring microwave resonator for uniform and efficient coupling of microwave magnetic field into nitrogen-vacancy (NV) centers in a diamond over a mm2 area. Uniformity and magnitude of delivered microwave field were measured using the Rabi nutation experiment on arrays of diamond nanowires with ensemble NV centers. An average Rabi nutation frequency of 15.65 MHz was measured over an area of 0.95 × 1.2 mm, for an input microwave power of 0.5 W. By mapping the Rabi nutation frequency to the magnetic field, the average value of the magnetic field over the aforementioned area and input microwave power was 5.59 G with a standard division of 0.24 G.