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 the finite-size system. Upon entering the quantum degenerate regime, the measured density response to an external force sharply increased, hinting at the peculiar prediction of an infinite compressibility of the deeply degenerate Bose gas. The findings could point the way to new types of sensors that can measure minute forces…read more. TEHNICAL ARTICLEÂ