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Excitons in cuprous oxide are promising candidates for the observation of Bose–Einstein condensation. Based on a multi-component Hartree–Fock–Bogoliubov theory, Sobkowiak et al., pp. 1178ff., determined the density profiles and luminescence spectra of interacting para- and orthoexcitons in a stress induced potential trap. The cover figure shows the exciton densities (top) of a system with strong repulsion between the two ortho-species. The calculations suggest that the phase separation of the ortho-condensates is not directly observable in the respective spectra, but may be revealed by the W-shaped distortion in the spatially resolved spectrum of the thermal paraexcitons, which can be seen in the bottom figure. The experimental observation of this footprint would yield a minimum estimate of the relative strength of the respective interactions.