Research Projects

Nitrogen- vacancy center (NV center) is an atomic defect in diamond. As a precision quantum sensor, it has broad applications in quantum information, quantum computation networks and magnetometry . The electronic spin in a NV center can be manipulated by microwave and addressed using optical transitions . To deliver microwave to the NV centers, thin copper wire, loop coil, double split-ring resonator and planar ring resonator were developed. However detailed considerations to all the aspects including microwave power efficiency, spatial homogeneity of microwave magnetic field, wide bandwidth, access to optical path, simultaneous control mechanisms were not present in these existing designs. We propose a novel microwave near field antenna specifically designed for manipulation of NV centers in diamond. It is tunable and the precise fabrication requirement is abated. The working frequency is centered around 2.87 GHz with a broad bandwidth of about ~600 MHz. It ensures the detection of high dynamic range external magnetic fields and waivers the need of tuning and matching of the antenna. It also imparts spatial homogeneity of microwave magnetic field within the diamond substrate with the range of about 1 mm, easing wide spatial range magnetic field imaging. It is power efficient and the power rating requirement of microwave power amplifier is within the ambient air temperature. In the NV ensemble magnetometry, NV centers are oriented at different directions. This will result in multiple resonances with respect to the direction of the external magnetic fields. Broad bandwidth MW antenna is beneficial to efficiently excite the multiple resonances of the NV centers. Tuning and matching together with broad bandwidth can facilitate the experiments on high dynamic range magnetic field sensing and imaging via NV centers.