What is it about?

In a quantum lattice with a band structure, flat energy bands can arise. This macroscopic degeneracy comes with compact localized states. Tiny perturbations destroy the flatness and may lead to novel quantum phases. We apply quasiperiodic perturbations. Among our key findings is the existence of tunable energy regions hosting critical (multifractal) eigenstates.

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Why is it important?

Our research reveals a novel tunable transition between critical and insulating phases similar to the well known tunable transition between metallic and insulating phases. The novel tunablity offers prospects for generating critical states in specific energy regions under various circumstances.


This article explains how to tailor quasiperiodic perturbation to obtain critical eigenstates in flatbands. This is a first step towards new quests which may include the study of many-body interactions potentially leading to exotic multifractal phases close to many-body localization transition, which is of interest for quantum computer platform realizations, among others.

Sanghoon Lee

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This page is a summary of: Critical state generators from perturbed flatbands, Chaos An Interdisciplinary Journal of Nonlinear Science, July 2023, American Institute of Physics, DOI: 10.1063/5.0153819.
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