Quantum emitters with long-lived quantum memories are a promising scalable quantum system for repeater-based quantum communications, quantum sensing, and distributed quantum computing networks. Although color centers in solids have been successful, further improvements in the efficiency of optical control and detection and scalability are necessary for practical uses. Here, we demonstrate that single nitrogen-vacancy centers can be efficiently coupled in diamond inverted nanocones that can be fabricated directly on the high-quality CVD diamond surface by the all-direction diagonal dry etching using a solid cone-shaped Faraday cage. Since the inverted cone shape allows efficient photon collection thanks to the single-directional guiding of photons, we report 20-fold enhancement in the photon collection efficiency from a single emitter while preserving a long electron spin coherence time. Furthermore, we show that an inverted nanocone can be picked and placed on the target position with desired orientation by using conventional microprobe tips. The demonstrated structure can also be applied to similar emitters in other solids; thus, it can be used for finding new possibilities for scalable photonic quantum devices.
Bibliographical noteFunding Information:
This work is supported by the National Research Foundation of Korea (Grant Nos. 2019M3E4A107866011 and 2019M3E4A1079777), the KIST Institutional Research Program (Grant No. 2E29580), and the Global University Project (GUP) grant (GK13260) and the GIST Research Institute (GRI) grant (GK12870) funded by the GIST in 2020. J.W. acknowledges funding by the European Union via ERC grant SMeL and the project ASTERIQS as well as the Max Planck Society. The authors thank Seoyoung Paik for building the experimental setups and Il-Young Kim for technical assistance.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering