28 March 2023 Tue 3.50 pm

We add weak quasiperiodic perturbations to one dimensional two-band ladders with both bands flat (all-bands-flat). For weak perturbation, an additional projection onto a single flatband Hilbert space allows to study the properties of the eigenstates upon variation of the control parameters of the all-bands-flat ladder. We observe localized insulating states, and an entire parameter range hosting critical states. These critical states have multifractal behavior and support subdiffusive transport. The Critical-to-Insulator transition turns energy dependent upon increasing the strength of the quasiperiodic perturbations. We therefore discover fractality edges - energy dependent transitions between an insulator and criticality.

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