Complete delocalization and reentrant topological transition in a non-Hermitian quasiperiodic lattice
Ashirbad Padhan, Soumya Ranjan Padhi, Tapan Mishra
Abstract
We predict a complete delocalization of the localized states following the localization transition in a one-dimensional non-Hermitian Aubry-Andr\'e model with a generalized quasiperiodic potential. We show that the system first undergoes a transition from the delocalized phase to the localized phase and then to the delocalized phase as a function of the complex phase of the quasiperiodic potential of fixed strength revealing a reentrant delocalization transition. We further identify the localized region as topological in nature exhibiting a well-defined spectral winding number which vanishes in the delocalized phases resulting in a reentrant spectral topological transition. Moreover, we find that these two transitions occur through intermediate regions hosting both delocalized and localized states which also possess nontrivial winding numbers that are different from that of the localized phase.