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Q: Fachverband Quantenoptik und Photonik

Q 13: Quantum Gases (Bosons) III

Q 13.5: Talk

Tuesday, March 15, 2022, 11:30–11:45, Q-H10

Compressibility and the Equation of State of an Optical Quantum Gas in a Box — •Erik Busley, Leon Espert, Andreas Redmann, Kirankumar Umesh, Martin Weitz, and Julian Schmitt — Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, D-53115 Bonn

The compressibility of a medium, quantifying its response to mechanical perturbations, is a fundamental quantity 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. Here we demonstrate a measurement of the compressibility of a two-dimensional quantum gas of light in a box potential and obtain the equation of state of the optical medium. The experiment is carried out in a nanostructured dye-filled optical microcavity. Upon reaching quantum degeneracy we observe signatures of Bose-Einstein condensation in the finite-size system, and strikingly, the measured density response to an external force sharply increases, hinting at the peculiar prediction of an infinite compressibility of a Bose gas condensate [1].

[1] E. Busley et al., Science (accepted for publication)