Non-Hermitian strong bosonic clustering through interaction-induced caging

Guiding how interacting bosons gather at system boundaries underpins emerging quantum technologies. However, how the triple interplay of directional non-Hermitian hopping, bosonic repulsion, and band topology shapes such clustering is still not fully understood. Here we show that these ingredients cooperate to produce an emergent “cage” that traps bosons at a lattice edge, yielding system boundary densities far beyond those from interaction-induced trapping alone. This caging extends from our two-boson minimal model to many-body systems over broad interaction strengths and hopping asymmetries. The mechanism offers a general strategy to pin correlated particles without external barriers and could inform future designs of robust edge memories and energy-efficient transport devices. Editor Summary-Interacting bosons in non-Hermitian lattices challenge conventional expectations by clustering collectively rather than dispersing. In this work the authors uncover a counter-intuitive “caging” effect where repulsive interactions-rather than spreading particles-work with non-Hermiticity to pin bosons at one edge, beyond what non-Hermiticity alone predicts.