Wrocław University of Science and Technology
In this talk,I will summarize our efforts in experimental investigations of excitations ofexciton-polariton condensates in optically induced traps. I will show how wecan directly probe the excitation spectrum of the BEC in situ  and how theoccupation of excited states can differ from the conservative BEC inthermodynamic equilibrium . We hypothesize that a large noncondensed part insidethe trap strongly affects the spectrum of the polariton BEC.
 Pieczarka,M. et al. Observation of quantum depletion in a non-equilibriumexciton–polariton condensate. Nat. Commun. 11, 429 (2020).
 Pieczarka,M. et al. Bogoliubov excitations of a polariton condensate in dynamicalequilibrium with an incoherent reservoir. Phys. Rev. B 105, 224515 (2022).