Cover Story: Liu J, Shi MQ, Chen Z, Wang SM, Wang ZL et al. Quantum photonics based on metasurfaces. Opto-Electron Adv 4, 200092 (2021). 

This paper summarizes recent works on quantum optics based on micro/nano structures. Since its birth, quantum optics has been full of controversies, among which the most famous debate is between Niels Bohr and Einstein. The main arguments are the locality and reality of classical physics, and the corresponding aspects are the non-locality and uncertainty for quantum physics. It was not until bell's inequality that it became experimentally possible to prove the completeness of quantum physics. At the same time, advanced technologies based on quantum physics are emerging one after another, such as quantum computing, quantum simulation, quantum communication and quantum precision measurement, etc. These technologies based on new quantum physics will bring revolutions to human life. In order to better serve the human society with quantum technologies, it is particularly important to prepare micro/nano optical devices with strong stability, high efficiency and scalability. This not only makes the exploration of quantum physics more convenient and stable, but also introduces new degrees of freedom to enrich the possibilities of quantum technologies.