Information metamaterial: Bridging the physical world and digital world

Metamaterials described by effective medium parameters have shown powerful abilities in controlling the physical properties of electromagnetic waves. In this special topic, we proposed to represent the metamaterials by digital coding elements to reach information metamaterials. On one hand, a single information metamaterial can switch many different functions in real time in programmable manner (e.g. programmable radar and imaging). On the other hand, the digital coding representation of metamaterial builds up a bridge between the electromagnetic physical world and digital world, and hence the digital concepts (e.g. Shannon entropy and convolution) can be used to control the metasurface physics. Owing to the strong capabilities in manipulating waves and digital signals simultaneously and easy integrations with machine-learning algorithms, the information metamaterials have found applications in real-time imaging, automatic target recognition, self-adaptive beam tracing, and new-architecture wireless communications.