Sanghoon Lee

PCS IBS (Comprehensive Exam)

28 March 2023 Tue 3.50 pm

                                      IBS Center for Theoretical Physics of Complex Systems (PCS), Administrative Office (B349), Theory Wing, 3rd floor

                                      Expo-ro 55, Yuseong-gu, Daejeon, South Korea, 34126 Tel: +82-42-878-8633                     

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.

  1. critical state generators from perturbed flatbands: critical-to-insulator transitions and fractality edges