Particle production between isometric frames on a Poincaré patch of AdS2

In a recent paper [J. P. M. Pitelli, Phys. Rev. D 99, 108701 (2019)], one of us showed that the vacuum state associated with conformal fields on a Poincaré patch of anti-de Sitter spacetime is not AdS invariant for fields satisfying nontrivial boundary conditions (by nontrivial, we mean neither Dirichlet nor Neumann) at the conformal boundary. In this way, two isometrically related observers in anti-de Sitter space have different notions of no particle content. Therefore, an observer who is suddenly transported to a different (but isometrically related) frame will feel a bath of particles. This process contradicts our intuitive notion based on our experience in Minkowski spacetime, where the vacuum is Lorentz invariant, and no particle is produced between boosted frames. We show that the total number of produced particles is finite but grows without limit when we approach (via isometric transformation) Dirichlet or Neumann boundary conditions since in these cases the vacuum is invariant.