Flat bands, sharp physics

Flat bands arise in periodic media when symmetries or fine-tuning result in perfect wavepacket localisation. Flat band localisation is fragile and exhibits remarkably sharp sensitivity to perturbations including interactions and disorder, leading to a variety of interesting quantum and classical phenomena. Originally a theoretical curiosity, advances in fabrication methods have allowed flat band physics to be observed down to the nanoscale. This article briefly reviews progress in the study of flat bands and disorder over the past decade and provides an outlook on where this exciting field is headed.