Phys.org  March 24, 2022 The compressibility of a medium, quantifying its response to mechanical perturbations is a fundamental property determined by the equation of state. For gases of material particles studies of the mechanical response are well established in fields from classical thermodynamics to cold atomic quantum gases. Researchers in Germany demonstrated the measurement of the compressibility of a two-dimensional quantum gas of light in a box potential and obtained the equation of state for the optical medium. The experiment was carried out in a nanostructured dye-filled optical microcavity. They observed signatures of Bose-Einstein condensation at high phase-space densities in […]