Phase transition of photons and gravitons in a Casimir box

Abstract

A first order phase transition for photons and gravitons in a Casimir box is studied analytically from first principles with a detailed understanding of symmetry breaking due to the boundary conditions. It is closely related to Bose-Einstein condensation and accompanied by a quantum phase transition whose control parameter is the chemical potential for optical helicity.

arXiv comment15 pages, 2 figures. v3: Improved presentation, minor typos corrected, results unchanged, version accepted for publication in CQG. v2: Minor changes, mostly references