Gapless fluctuations and exceptional points in semiconductor lasers
The study investigates a gapless regime in semiconductor laser fluctuations, analogous to gapless superconductivity. It finds this occurs when the decay rate of occupation fluctuations differs from the polarization fluctuation rate. The transition between the gapless and gapped spectral states is marked by a third-order exceptional point, providing a non-equilibrium analog for studying complex spectral phenomena.