NV-color centers in nanodiamond as a photon emitter embedded in whispering-gallery-mode optical resonator*

Development of reliable and stable photon source is crucial for applications in quantum technology, as well as fundamental experiment and metrology. NV(Nitrogen-vacancy) color center in diamond, are among the promising candidate for photon source. Although coupling of color centers with an high-Q optical cavity has high potential, fabricating optical cavities embedding defect centers have been challenging tasks with recent initial demonstrations.
Here, we present a novel approach to fabricate high-Q optical Whispering-Gallery-Mode resonator comprising NV-color center. Starting from disk resonator coated with nanodiamond particles, we also fabricate microtoroid optical resonator. Fabricated microtoroid resonator with NV-center shows Q-factor above 10⁷ at telecom wavelength. A scanning photoluminescence spectrum also confirms stable photoemission inside the microtoroid resonators. With further development of this hybrid UHQ resonator, we expect the realization of robust platform for cavity QED and quantum metrology