Exciton polariton critical non-Hermitian skin effect with spin-momentum-locked gains

The critical skin effect, an intriguing phenomenon in non-Hermitian systems, displays sensitivity to system size and manifests distinct dynamical behaviors. In this Letter, we propose a scheme to achieve the critical non-Hermitian skin effect of exciton polaritons in an elongated microcavity system. We show that by utilizing longitudinal-transverse spin splitting and spin-momentum-locked gain, a critical non-Hermitian skin effect can be achieved in a continuous system without the need for an underlying lattice. We find that a phase transition can be induced by changing the cavity detuning with respect to the exciton energy. We identify a measurable order parameter associated with this phase transition and demonstrate the corresponding critical behavior. Our work offers a flexible approach to manipulating non-Hermitian phases of exciton polaritons, thereby expanding the potential applications of polaritonic devices.