Interaction induced bi-skin effect in an exciton-polariton system

The non-Hermitian skin effect can be realized through asymmetric hopping between forward and backward directions, where all the modes of the system are localized at one edge of a finite 1D lattice. However, achieving such an asymmetric hopping in optical systems is far from trivial. Here we show theoretically that in a finite chain of 1D exciton-polariton micropillars with symmetric hopping, the inherent non-linearity of the system can exhibit a bi-skin effect, where the modes of the system are localized at the two edges of the system. To show the topological origin of such modes, we calculate the winding number.