Enhancement of single-photon emission of nitrogen-vacancy centers in nanodiamonds via hybrid plasmonic platforms
Yen-Chun Chen1*, Chun-Yuan Wang2, Shangir Gwo2, Wen-Hao Chang1
1Department of electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2Department of physics, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Yen-Chun Chen, email:ycchen1988@gmail.com
Single photon, a particle performed strong quantum behavior, is an ideal quantum bit in the application of quantum computations and quantum communications. Nitrogen-vacancy (NV) centers in nanodiamonds (NDs) have been demonstrated as a desirable single-photon source for a decade. Because of a robust lattice structure, a zero-phonon-line emission (638 nm) can be observed at room temperature. However, due to total internal reflection, the high refraction index of diamond limits extraction efficiency of single photons.
Here we spread NDs on hybrid plasmonic platforms, which are constructed from an atomically smooth Al2O3 film capping on single crystalline gold flakes. Plasmonic fields, excited by single photons, are trapped in the 5-nm dielectric gap because of a contrast of refractive indices and focus the radiative pattern of NV centers in NDs. In experiment, we observed the single-photon extraction rate is raised by a factor of 6 comparing with NDs on the glass substrate. This hybrid plasmonic platform with a large-area enhancement of single photon generation rates shows a benefit to application in quantum information science.

Keywords: Surface plasmon, nanodiamonds, Nitrogen-Vacancy centers, single-photon sources