Bose condensation of squeezed light

Light with a chemical potential and no mass is shown to possess a general phase-transition curve to Bose-Einstein condensation. This limiting density and temperature range is found by the diverging in-medium potential range of effective interaction. The inverse expansion series of the effective interaction from Bethe-Salpeter equation is employed exceeding the ladder approximation. While usually the absorption and emission with Dye molecules is considered, here it is proposed that squeezing can create also such a mean interaction leading to a chemical potential. The equivalence of squeezed light with a complex Bogoliubov transformation of interacting Bose system with finite lifetime is established with the help of which an effective gap is deduced where the squeezing parameter is related to an equivalent gap by $|\Delta(\omega)|={\hbar \omega/( \coth {2|z(\omega)|}-1)}$. This gap phase creates a finite condensate in agreement with the general limiting density and temperature range. In this sense it is shown that squeezing induces the same effect on light as an interaction leading to possible condensation. The phase diagram for condensation is presented due to squeezing and the appearance of two gaps is discussed.

K. Morawetz · 2018