Shaping topological states in acoustics: how we unveiled the invisible world of quantum physics using actively controlled loudspeakers
Topological materials have attracted considerable attention in material sciences over the past few decades due to their remarkable conductive properties that are robust to defects and impurities. However, the challenge of reaching the atomic-scale impedes a deeper understanding of topological phenomena. Fortunately, macroscopic metamaterials - structured materials engineered to obtain such unusual properties – have been developed to better understand the wonders of the quantum real. Indeed, the wavefunction of scattering electrons can behave like ordinary waves such as sound.
As a proof of concept, we present an actively tunable metamaterial composed of an array of loudspeakers capable of exhibiting prescribed topological features similar to those found in the Su-Schrieffer-Heeger system - a one-dimensional chain of coupled dimers that can host topological states.
Active control enables us to simply configure our system to yield topological interface states that are robust against high level of disorder introduced in the system.
Beyond topology, this active system paves the way to unravel novel exotic phenomena. For example, one could imagine creating a lattice composed of time-variant nonlinear and non-reciprocal coupling of Fibonacci-numbered resonators – the possibilities are plentiful.