Fig. 3: Measurement of the renormalized excitation spectrum.
From: Observation of quantum depletion in a non-equilibrium exciton–polariton condensate
a Full photoluminescence of the high-density exciton–polariton condensate at the photonic detuning (Δ = −3.7 meV) and n ≈ 1340 μm−2. b Excitation spectrum of the polariton condensate in a measured with a momentum edge filter covering the signal up to k|| ≈ 0.55 μm−1. c Excitation spectrum measured at the excitonic detuning (Δ = + 1.8 meV) and n ≈ 1848 μm−2. Colour scales are logarithmic and images (b, c) are saturated. Green solid lines indicate extracted spectral positions of the branches. Solid white lines represent single-particle dispersions and dashed lines correspond to the renormalized Bogoliubov dispersions fitted to the data.
