Creating logic gates using actuated phononic crystals

In recent times, the use of acoustic metamaterials has opened to acoustics many technical developments that were initially associated only with light. In this work, we discuss how this trend brings naturally to the developing field of acoustic computing. In particular, we show how multi-level logic gates can be created using mechanically-actuated phononic crystals. We show how to design unit cells that exploit topological symmetries (or the lack of them) to create basic ON/OFF switches. We demonstrate how these switches can be combined into the main logic gates (AND, OR, NOT, and XOR) and how these might be used in practice. Finally, we realise two of these devices, based on audible sounds, and use ad-hoc measurement methods to assess their performance compared to theory.