|
内容記述 |
The diamond quantum sensors based on NV (Nitrogen-Vacancy) center is one of the promising candidates for magnetoencephalography, which requires sub-pT/√Hz magnetic field sensitivity. To achieve high sensitivity, it is necessary to excite millimeter-scale diamond by light and microwaves, and to collect fluorescence efficiently from NV centers. We proposed and fabricated a printed circuit board-based loop-gap microwave resonator to improve the spatial uniformity of the microwave field to the millimeter volume of diamond. Moreover, our resonator can incorporate efficient optical excitation and collection, and heat dissipation. Using this resonator, we demonstrated that the diamond NV ensemble (1016cm-3), synthesized by CVD process, were driven within an area of 5 mm square. The average strength of the microwave magnetic field was 0.53 G at 46 dBm input power, which is sufficient to drive the NV centers for our sensor. The uniformity of the microwave field strength was within 50 % of the peak-to-peak amplitude for 5 mm square. It can be estimated that our loop-gap resonator has a potential to achieve a sensitivity of sub-pT/√Hz with 1mm3 volume diamond. |
