Quantization of scalar fields in curved background, deformed Hopf   algebra and entanglement
  A suitable deformation of the Hopf algebra of the creation and annihilation operators for a complex scalar field, initially quantized in Minkowski space--time, induces the canonical quantization of the same field in a generic gravitational background. The deformation parameter q turns out to be related to the gravitational field. The entanglement of the quantum vacuum appears to be robust against interaction with the environment. 
A. Iorio (Physics Dept. "E.R.Caianiello", University of Salerno,   Italy), G. Lambiase (Physics Dept. "E.R.Caianiello", Univ...