Topological enhancement of exciton-polariton coherence with non-Hermitian morphing

The non-Hermitian skin effect (NHSE) has been intensely investigated over the past few years and has unveiled new topological phases, which have no counterparts in Hermitian systems. Here we consider the hybridization between the NHSE in an exciton-polariton waveguide and a localized defect mode. By tuning the non-Hermiticity, we find that the resulting ground state of the system is both spatially extended and energetically separated from other modes in the system. When polariton lasing occurs in the system, we find an enhanced spatial coherence (of typically 30 times longer) compared to regular waveguides, which is robust in the presence of disorder.