Four-wave mixing excitations in a dissipative polariton quantum fluid
The Bogoliubov transformation of a polariton quantum fluid has recently been revealed in the four-wave mixing response of a driven microcavity polariton gas. In this work, we investigate the modifications that the dual nature of microcavity polaritons produce on the excitations of this particular half-light-half-matter quantum fluid. We discuss in particular the Bogoliubov character of the excitations of a lower polariton superfluid when it coexists with upper polaritons. We show unique effects resulting from the interplay between polariton decay and Bogoliubov transformation such as the modification of the Bogoliubov dispersion or the slowing down of the four-wave mixing dynamics.