Phase transitions and intermediate phases induced by nearest-neighbor dipolar interaction in a nonreciprocal non-Hermitian extended Bose-Hubbard model
Phys. Rev. B 114, 214301 – Published 2 October, 2026
DOI: https://doi.org/10.1103/gklh-w392
Abstract
The interplay of non-Hermiticity, nonreciprocal hopping, and interparticle interactions provides new possibilities for tuning localization and emergent phase transitions in quasiperiodic systems. Here we investigate, within the two-body Fock space, the effects of nearest-neighbor dipolar interaction on the spectral structure and localization behavior of two bosons in a nonreciprocal non-Hermitian quasiperiodic extended Bose-Hubbard model. The analysis is restricted to the two-body sector, while higher-occupancy sectors are not considered. We find that dipolar interaction replaces the single transition point of the noninteracting system by an intermediate mobility-edge phase. This intermediate phase can be understood as a consequence of the successive localization of doublon states and nearest-neighbor states. It originates from the distinct spectral and Fock-space localization thresholds of different two-particle eigenstates induced by dipolar interaction. Under open boundary conditions, both doublon and nearest-neighbor states exhibit non-Hermitian skin effects, leading to distinct boundary accumulation and relaxation dynamics in different phases. Our results deepen the understanding of two-body Fock-space localization transitions and skin effects in non-Hermitian quasiperiodic systems, and may provide new insight into non-Hermitian few-body physics in quasiperiodic lattices.
