PhD defense — Clara Piekarski

Clara is now doctor! After Myrann on friday, Clara defended this monday, her thesis on “Binary mixtures of quantum fluids of light”.

Well done and well deserved, congrats Clara!

Thesis summary

This thesis demonstrates the realization of a binary mixture of quantum fluids of light. Fluids of light rely on the mathematical mapping between the Gross-Pitaevskii equation, which describes weakly interacting Bose-Einstein condensates, and the propagation of a laser through a nonlinear Kerr medium — in our case, a hot rubidium vapor. We can then study superfluidity, and more generally Bose gas physics, in a photonic system. In this work, we show that the two circular polarizations of light follow coupled Gross-Pitaevskii equations, and can therefore be considered as the two components of a binary Bose gas. We characterize the intra- and inter-component interactions and demonstrate the realization of a two-component fluid of light in the miscible and in the non-miscible regime. In the miscible regime, we proceed to the measurement of the elementary density and spin excitations, characteristic of a superfluid mixture. In the non-miscible regime, we prepare the fluid in a homogeneous mixture to study the spontaneous separation of the two components into domains, also called coarsening dynamics. We also show that the non-miscible binary fluid is a promising platform to study hydrodynamic instabilities at the interface between the two components.