Artificial flat band systems: from lattice models to experiments

TL;DR

This paper reviews the design, realization, and future prospects of flat band systems in various physical settings, highlighting their unique spectral properties and strongly-interacting phases of matter.

Contribution

It provides a comprehensive overview of flat band systems from theoretical models to experimental implementations across multiple platforms.

Findings

Flat bands can arise from symmetries or fine-tuned couplings.

Flat bands have been observed in electronic, atomic, and photonic systems.

They enable the study of strongly-interacting phases of matter.

Abstract

Certain lattice wave systems in translationally invariant settings have one or more spectral bands that are strictly flat or independent of momentum in the tight binding approximation, arising from either internal symmetries or fine-tuned coupling. These flat bands display remarkable strongly-interacting phases of matter. Originally considered as a theoretical convenience useful for obtaining exact analytical solutions of ferromagnetism, flat bands have now been observed in a variety of settings, ranging from electronic systems to ultracold atomic gases and photonic devices. Here we review the design and implementation of flat bands and chart future directions of this exciting field.