The Maryland model is a lattice model with a quasiperiodic tangent potential — a workhorse for studying localization transitions. Its non-Hermitian extension, where the potential acquires an imaginary part, opens new possibilities: states that would be localized in the Hermitian case can become extended.
The authors (arXiv:2603.22682) study a mosaic variant where the non-Hermitian potential is applied only at every κ-th site. When κ ≥ 2, robust extended bands emerge that persist regardless of the potential strength. The extended states survive not because the disorder is weak but because the mosaic pattern creates spatial channels that circumvent the localizing potential.
The through-claim: the persistence of extended states in the mosaic model is topologically protected by the spatial modulation pattern, not by fine-tuning. The extended bands exist for all potential strengths when κ ≥ 2 — the modulation period, not the potential amplitude, determines whether transport survives. This suggests engineered spatial patterns as a route to robust wave transport in non-Hermitian systems.