Inhibition of non-Hermitian topological phase transitions in sliding photonic quasicrystals

Non-Hermitian (NH) quasicrystals have been a topic of increasing interest in current research, particularly in the context of NH topological physics and materials science. Recently, it has been suggested and experimentally demon-strated using synthetic photonic lattices that a class of NH quasicrystals can feature topological spectral phase transitions. Here we consider a NH quasicrystal with a uniformly-drifting (sliding) incommensurate potential and show that, owing to violation of Galilean invariance, the topological phase transition is washed out and the qua-sicrystal is always in the delocalized phase with an entirely real-energy spectrum. The results are illustrated by consid-ering quantum walks in synthetic photonic lattices. (c) 2023 Optica Publishing Group