Parametric amplification of topological interface states in synthetic Andreev bands

A driven-dissipative nonlinear photonic system (e.g. exciton-polaritons) can operate in a gapped superfluid regime. We theoretically demonstrate that the reflection of linear wave on this is an analogue Andreev electron superconductor. normal region surrounded by two superfluids found to host Andreev-like bound states. These states form topological synthetic bands versus phase difference between superfluids. Changing width allows invert band topology and create "interface" Instead demonstrating crossing, are attracted non-linear non-Hermitian coupling bosonic systems which gives rise self-amplified strongly occupied state.