Over the past thirty years, with the generation of optical quantum states in the experiments, the field of quantum information science has developed rapidly. A series of quantum information protocols have been proposed and implemented experimentally. For example, quantum teleportation, quantum entanglement swapping, quantum dense coding, quantum key distribution, and quantum secret sharing. The implementation of these quantum information protocols has laid the foundation for the development of quantum communication. At the same time, optical quantum states make the measurement accuracy successfully exceed the standard quantum limit, and they have been widely used in quantum metrology and quantum sensing.

In the age of the Three Kingdoms, Liu Bei's steed was named Dilu. Its unaesthetic appearance once led people to believe that the horse was cursed, and would bring misfortune to people who rided it. Bei had for sure heard about the rumor, but never thought about abandoning the horse, even during his most difficult times. Once Bei was attending an ill-intentioned feast in Jingzhou, where a local warlord arranged a plot to hunt him down at the scene. Not long before the warlord made the move, Bei was informed and he fled, riding Dilu. In a fluster, he got lost and trapped in the middle of a river called Tanxi. No horse had ever been able to travel through Tanxi because it was wide and had strong undercurrent. The enemy pursuers were getting really close and Bei had nowhere to hide. In despair, he said, "Dilu, Dilu, you bring me misfortune after all," and planned to give up.

Geometric phase, also known as PB phase, has a profound meaning in many branches of physics, such as condensed matter physics and quantum systems, and has been extended to classical optics. Although geometric phase has a long history of research, with the development of optical research towards the sub wavelength scale, this ancient concept has been pregnant with new connotation, which brings new optical theories, micro/nano structure devices and optical applications.

In mathematics, topology is concerned with the properties of a geometric object that are preserved under continuous deformations. In physics, topology is generally manifested in the evolution of the eigenstates. With the celebrated quantum Hall effect introducing topological Chern invariants into physical systems for the first time, interesting phenomena based on topology have been vigorously developed in various fields of physics.

Information metasurfaces develop from digital coding and programmable metasurfaces, the initial idea of which is to design the metamaterials structure pattern in a digital way. Compared to previous research focusing on the material characteristics and function realization, information metasurfaces discuss from the perspective of information science and produce a totally digital pattern on metamaterial configuration by digital and discrete meta-element.

Photonics Insights will be a high-quality，peer-reviewed, Diamond Open Access journal. It will feature review articles which present the current status of a given topic, with background, research progress, conclusions, and possible future developments.