Thermodynamics of Trapped Photon Gases at Dimensional Crossover from 2D to 1D (B6)

🔓 Enrico Stein and Axel Pelster:

New Journal of Physics 24, 023013 (2022)

Photon Bose-Einstein condensates are characterised by a quite weak interaction, so they behave nearly as an ideal Bose gas. Moreover, since the current experiments are conducted in a microcavity, the longitudinal motion is frozen out and the photon gas represents effectively a two-dimensional trapped gas of massive bosons. In this paper we therefore focus on a harmonically confined ideal Bose gas in two dimensions, where the anisotropy of the confinement allows for a dimensional crossover. If the anisotropy is even large enough so that the squeezed direction is frozen out, then only one degree of freedom survives and the system can be considered to be quasi-one dimensional. We work out the thermodynamic properties for such a system analytically and examine, in particular, the dimensional information which is contained in the respective thermodynamic quantities. With this our results are useful for future experiments of photon gases at the dimensional crossover from 2D to 1D in view of determining their effective dimensionality from thermodynamic quantities.